Add uv_meter_as7331 from https://github.com/michaelbaisch/uv_meter

git-subtree-dir: uv_meter_as7331
git-subtree-mainline: 5fed652ef9f9144727e6aa4764feffbddd81347a
git-subtree-split: 4c32e20ca842201191fb77ded98b1c0b8dbc81f0

uv_meter_as7331/.github/workflows/build.yml

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+name: "UV Meter: Build for multiple SDK sources"
+# This will build your app for dev and release channels on GitHub. 
+# It will also build your app every day to make sure it's up to date with the latest SDK changes.
+# See https://github.com/marketplace/actions/build-flipper-application-package-fap for more information
+
+on:
+  push:
+    branches: 
+      - main 
+  pull_request:
+    branches:
+      - '**'
+  schedule: 
+    # do a build every day
+    - cron: "1 1 * * *"
+
+jobs:
+  ufbt-build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        include:
+          - name: Official Dev channel
+            sdk-channel: dev
+          - name: Official Release channel
+            sdk-channel: release
+          - name: Unleashed Dev
+            sdk-index-url: https://up.unleashedflip.com/directory.json
+            sdk-channel: dev
+          - name: Unleashed Release
+            sdk-index-url: https://up.unleashedflip.com/directory.json
+            sdk-channel: release
+          - name: Momentum Dev
+            sdk-index-url: https://up.momentum-fw.dev/firmware/directory.json
+            sdk-channel: dev
+          - name: Momentum Release
+            sdk-index-url: https://up.momentum-fw.dev/firmware/directory.json
+            sdk-channel: release
+    name: 'ufbt: Build for ${{ matrix.name }}'
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Build with ufbt
+        uses: flipperdevices/flipperzero-ufbt-action@v0.1.3
+        id: build-app
+        with:
+          sdk-channel: ${{ matrix.sdk-channel }}
+          sdk-index-url: ${{ matrix.sdk-index-url }}
+      - name: Upload app artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: ${{ github.event.repository.name }}-${{ steps.build-app.outputs.suffix }}
+          path: ${{ steps.build-app.outputs.fap-artifacts }}

uv_meter_as7331/.gitignore

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+dist/*
+.vscode
+.clang-format
+.clangd
+.editorconfig
+.env
+.ufbt

uv_meter_as7331/.gitsubtree

@@ -0,0 +1 @@
+https://github.com/michaelbaisch/uv_meter main /

uv_meter_as7331/AS7331.cpp

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+/**
+ * @file AS7331.cpp
+ * @brief Implementation of AS7331 UV Spectral Sensor Driver
+ */
+
+#include "AS7331.hpp"
+#include <furi_hal_i2c.h>
+#include <furi_hal.h>
+#include <cmath> // For pow()
+
+// Prevent compiler optimization, for debugging.
+// #pragma GCC optimize("O0")
+
+// Timeout value for I2C operations (in milliseconds)
+#define AS7331_I2C_TIMEOUT 100
+
+// Constructor
+AS7331::AS7331(uint8_t i2c_address_7bit)
+    // Convert 7-bit to 8-bit address
+    : _i2c_addr_8bit(i2c_address_7bit << 1)
+    // Initialize to invalid mode to force first-time setup
+    , _deviceMode(static_cast<as7331_device_mode_t>(0x00))
+    , _power_down(true)
+    , _gain(GAIN_2)
+    , _integration_time(TIME_64MS)
+    , _enable_divider(false)
+    , _divider(DIV_2)
+    , _clock_frequency(CCLK_1_024_MHZ)
+    , _standby(false)
+    , _measurement_mode(MEASUREMENT_MODE_COMMAND) {
+}
+
+// Initialize the sensor
+bool AS7331::init(const uint8_t& i2c_address_7bit) {
+    uint8_t detected_address_7bit = 0;
+
+    if(i2c_address_7bit == 0x0) {
+        // Scan I2C bus for AS7331 device
+        detected_address_7bit = scan_i2c_bus();
+        if(detected_address_7bit == 0x0) {
+            FURI_LOG_E(
+                "AS7331",
+                "Failed to find an AS7331 device with one of the four valid addresses on the I2C bus.");
+            return false;
+        }
+    } else {
+        if(deviceReady(i2c_address_7bit)) {
+            detected_address_7bit = i2c_address_7bit;
+        } else {
+            FURI_LOG_E("AS7331", "No device found at I2C address 0x%02X.", i2c_address_7bit);
+            return false;
+        }
+    }
+    // Set the I2C address (7-Bit to 8-Bit)
+    _i2c_addr_8bit = detected_address_7bit << 1;
+
+    // Wake up the device from power-down mode
+    if(!setPowerDown(false)) {
+        FURI_LOG_E("AS7331", "Failed to wake up the device from power-down mode.");
+        return false;
+    }
+
+    // Set the device into configuration mode
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+    bool success = setDeviceMode(DEVICE_MODE_CONFIG);
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+    if(!success) {
+        FURI_LOG_E("AS7331", "Failed to set the device into configuration mode.");
+        return false;
+    }
+
+    // Populate local configuration variables from device registers
+    if(!updateLocalConfig()) {
+        FURI_LOG_E("AS7331", "Failed to read device configuration registers.");
+        return false;
+    }
+
+    // Read the device ID
+    as7331_agen_reg_t deviceID;
+    if(!getDeviceID(deviceID)) {
+        FURI_LOG_E("AS7331", "Failed to read device ID.");
+        return false;
+    }
+    // Compare with expected Device ID
+    if(deviceID.byte != ExpectedAGENContent) {
+        FURI_LOG_E(
+            "AS7331",
+            "Device ID mismatch: expected 0x%02X, got 0x%02X.",
+            ExpectedAGENContent,
+            deviceID.byte);
+        return false;
+    }
+
+    return true;
+}
+
+// Set sensor gain (CREG1:GAIN)
+bool AS7331::setGain(const as7331_gain_t& gain) {
+    if(gain > GAIN_1) {
+        FURI_LOG_E("AS7331", "Invalid gain value: %d.", gain);
+        return false;
+    }
+
+    as7331_creg1_reg_t creg1;
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // Ensure we are in configuration mode
+    if(!setDeviceMode(DEVICE_MODE_CONFIG)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed set device mode to configuration.");
+        return false;
+    }
+
+    // Read CREG1
+    if(!readRegister(RegCfgCreg1, creg1.byte)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read CREG1 register from device.");
+        return false;
+    }
+
+    // Write new gain value
+    creg1.gain = gain;
+    if(!writeRegister(RegCfgCreg1, creg1.byte)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to write gain value to device: %d.", creg1.gain);
+        return false;
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    // Update local config
+    _gain = gain;
+
+    return true;
+}
+
+// Set integration time (CREG1:TIME)
+bool AS7331::setIntegrationTime(const as7331_integration_time_t& time) {
+    // Validate integration time value
+    if(time > TIME_16384MS) {
+        FURI_LOG_E("AS7331", "Invalid integration time value: %d.", time);
+        return false;
+    }
+
+    // Automatically set divider depending on ADC resolution to prevent overflow
+    // Since this voids advantages of higher integration times, remove once overflow checking is implemented.
+    /*
+    int adc_resolution;
+    if(time == 15) {
+        // Special case: Same as TIME 0
+        adc_resolution = 10;
+    } else {
+        adc_resolution = 10 + time;
+    }
+    if(adc_resolution > 16) {
+        as7331_divider_t divider = static_cast<as7331_divider_t>(adc_resolution - 17);
+        setDivider(divider, true);
+    } else if(_enable_divider) {
+        setDivider(DIV_2, false);
+    }
+    */
+
+    as7331_creg1_reg_t creg1;
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // Ensure we are in configuration mode
+    if(!setDeviceMode(DEVICE_MODE_CONFIG)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to set device mode to configuration.");
+        return false;
+    }
+
+    // Read CREG1
+    if(!readRegister(RegCfgCreg1, creg1.byte)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read CREG1 register from device.");
+        return false;
+    }
+
+    // Write new integration time value
+    creg1.integration_time = time;
+    if(!writeRegister(RegCfgCreg1, creg1.byte)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E(
+            "AS7331",
+            "Failed to write integration time value to device: %d.",
+            creg1.integration_time);
+        return false;
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    // Update local config
+    _integration_time = time;
+
+    return true;
+}
+
+// Set output divider (CREG2:DIV)
+bool AS7331::setDivider(const as7331_divider_t& divider, const bool enable) {
+    // Validate divider value
+    if(divider > DIV_256) {
+        FURI_LOG_E("AS7331", "Invalid divider value: %d.", divider);
+        return false;
+    }
+
+    as7331_creg2_reg_t creg2;
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // Ensure we are in configuration mode
+    if(!setDeviceMode(DEVICE_MODE_CONFIG)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to set device mode to configuration.");
+        return false;
+    }
+
+    // Read CREG2
+    if(!readRegister(RegCfgCreg2, creg2.byte)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read CREG2 register from device.");
+        return false;
+    }
+
+    // Write new divider value and enable/disable it
+    creg2.divider = divider;
+    creg2.enable_divider = enable;
+    if(!writeRegister(RegCfgCreg2, creg2.byte)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E(
+            "AS7331",
+            "Failed to write divider settings to device: DIV=%d, ENABLE=%d.",
+            creg2.divider,
+            creg2.enable_divider);
+        return false;
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    // Update local config
+    _enable_divider = enable;
+    _divider = divider;
+
+    return true;
+}
+
+// Set clock frequency (CREG3:CCLK)
+bool AS7331::setClockFrequency(const as7331_clock_frequency_t& frequency) {
+    // Validate clock frequency value
+    if(frequency > CCLK_8_192_MHZ) {
+        FURI_LOG_E("AS7331", "Invalid clock frequency value: %d.", frequency);
+        return false;
+    }
+
+    as7331_creg3_reg_t creg3;
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // Ensure we are in configuration mode
+    if(!setDeviceMode(DEVICE_MODE_CONFIG)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to set device mode to configuration.");
+        return false;
+    }
+
+    // Read CREG3
+    if(!readRegister(RegCfgCreg3, creg3.byte)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read CREG3 register from device.");
+        return false;
+    }
+
+    // Write new clock frequency value
+    creg3.clock_frequency = frequency;
+    if(!writeRegister(RegCfgCreg3, creg3.byte)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E(
+            "AS7331",
+            "Failed to write clock frequency value to device: %d.",
+            creg3.clock_frequency);
+        return false;
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    // Update local config
+    _clock_frequency = frequency;
+
+    return true;
+}
+
+// Set measurement mode (CREG3:MMODE)
+bool AS7331::setMeasurementMode(const as7331_measurement_mode_t& mode) {
+    // Validate measurement mode value
+    if(mode > MEASUREMENT_MODE_SYNC_START_END) {
+        FURI_LOG_E("AS7331", "Invalid measurement mode value: %d.", mode);
+        return false;
+    }
+
+    as7331_creg3_reg_t creg3;
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // Ensure we are in configuration mode
+    if(!setDeviceMode(DEVICE_MODE_CONFIG)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to set device mode to configuration.");
+        return false;
+    }
+
+    // Read CREG3
+    if(!readRegister(RegCfgCreg3, creg3.byte)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read CREG3 register from device.");
+        return false;
+    }
+
+    // Write new measurement mode value
+    creg3.measurement_mode = mode;
+    if(!writeRegister(RegCfgCreg3, creg3.byte)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E(
+            "AS7331", "Failed to write measurement mode to device: %d.", creg3.measurement_mode);
+        return false;
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    // Update local config
+    _measurement_mode = mode;
+
+    return true;
+}
+
+// Enable or disable power down state (OSR:PD)
+bool AS7331::setPowerDown(const bool& power_down) {
+    // The power-down feature affects both operational states: configuration and measurement.
+    // When the power-down state is activated while the device is in a measurement cycle,
+    // the power-down action is only executed during the intervals between consecutive conversions.
+
+    // Power Down Current Consumption: max 1µA
+    // Startup Time after Power Down state: 1.2-2ms
+
+    as7331_osr_reg_t osr;
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // OSR is accessible in any mode
+    // Read OSR register
+    if(!readOSRRegister(osr)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read OSR register from device.");
+        return false;
+    }
+
+    // Check if the desired power down state is already set
+    if(osr.power_down != power_down) {
+        osr.power_down = power_down; // Set PD bit
+
+        // Write back the OSR register
+        // Local configuration (_power_down) is updated in writeOSRRegister
+        if(!writeOSRRegister(osr)) {
+            furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+            FURI_LOG_E("AS7331", "Failed to write power down state to device: %d.", power_down);
+            return false;
+        }
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    return true;
+}
+
+// Put the sensor in standby mode or wake it up (CREG3:SB)
+bool AS7331::setStandby(const bool& standby) {
+    // Standby Current Consumption: max 970 µA
+    // Startup Time after Standby state: 4-5 µs
+
+    as7331_creg3_reg_t creg3;
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // Ensure we are in configuration mode
+    if(!setDeviceMode(DEVICE_MODE_CONFIG)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to set device mode to configuration.");
+        return false;
+    }
+
+    // Read CREG3
+    if(!readRegister(RegCfgCreg3, creg3.byte)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read CREG3 register from device.");
+        return false;
+    }
+
+    // Check if the desired standby state is already set
+    if(creg3.standby != standby) {
+        creg3.standby = standby; // Set SB bit
+
+        // Write back the CREG3 register
+        if(!writeRegister(RegCfgCreg3, creg3.byte)) {
+            furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+            FURI_LOG_E("AS7331", "Failed to write standby state to device: %d.", standby);
+            return false;
+        }
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    // Update local config
+    _standby = standby;
+
+    return true;
+}
+
+// Start the measurement (OSR:SS = 1)
+bool AS7331::startMeasurement() {
+    as7331_osr_reg_t osr;
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // Ensure we are in measurement mode
+    if(!setDeviceMode(DEVICE_MODE_MEASURE)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to set device mode to measurement.");
+        return false;
+    }
+
+    // Read OSR register
+    if(!readOSRRegister(osr)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read OSR register from device.");
+        return false;
+    }
+
+    // Check if measurement is already started
+    if(osr.start_state != 1) {
+        osr.start_state = 1; // Set SS bit to start measurement
+
+        // Write back OSR register
+        if(!writeOSRRegister(osr)) {
+            furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+            FURI_LOG_E("AS7331", "Failed to write OSR register to start measurement.");
+            return false;
+        }
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    return true;
+}
+
+// Stop the measurement (OSR:SS = 0)
+bool AS7331::stopMeasurement() {
+    as7331_osr_reg_t osr;
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // Read OSR register
+    if(!readOSRRegister(osr)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read OSR register from device.");
+        return false;
+    }
+
+    // Check if measurement is already stopped
+    if(osr.start_state != 0) {
+        osr.start_state = 0; // Clear SS bit to stop measurement
+
+        // Write back OSR register
+        if(!writeOSRRegister(osr)) {
+            furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+            FURI_LOG_E("AS7331", "Failed to write OSR register to stop measurement.");
+            return false;
+        }
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    return true;
+}
+
+// Wait for measurement to complete based on conversion time
+void AS7331::waitForMeasurement() {
+    double TCONV = getConversionTime();
+
+    if(TCONV > 0) {
+        // Wait for TCONV time, adding a small buffer
+        furi_delay_ms(static_cast<uint32_t>(TCONV * 1000) + 1); // Add 1 ms to ensure completion
+    }
+}
+
+// Get raw measurement results
+bool AS7331::getRawResults(RawResults& rawResults) {
+    uint8_t buffer[6]; // Each result is 2 bytes, so 3 results * 2 bytes = 6 bytes
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // Ensure we are in measurement mode
+    if(!setDeviceMode(DEVICE_MODE_MEASURE)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to set device mode to measurement.");
+        return false;
+    }
+
+    // Read all measurement results in one I²C transaction
+    if(!readRegisters(RegMeasResultA, buffer, 6)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read measurement results from device.");
+        return false;
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    // Combine the bytes into 16-bit values (LSB first)
+    rawResults.uv_a = (static_cast<uint16_t>(buffer[1]) << 8) | buffer[0];
+    rawResults.uv_b = (static_cast<uint16_t>(buffer[3]) << 8) | buffer[2];
+    rawResults.uv_c = (static_cast<uint16_t>(buffer[5]) << 8) | buffer[4];
+
+    return true;
+}
+
+// Get processed measurement results with raw data
+bool AS7331::getResults(Results& results, RawResults& rawResults) {
+    bool success = true;
+
+    // Get the raw measurement results
+    success &= getRawResults(rawResults);
+
+    if(!success) {
+        return false;
+    }
+
+    // Calculate FSREe for each channel
+    double FSREe_A = calculateFSREe(UV_A, false);
+    double FSREe_B = calculateFSREe(UV_B, false);
+    double FSREe_C = calculateFSREe(UV_C, false);
+    FURI_LOG_I("AS7331", "FSREe_A: %f", FSREe_B);
+    FURI_LOG_I("AS7331", "FSREe_B: %f", FSREe_C);
+    FURI_LOG_I("AS7331", "FSREe_C: %f", FSREe_C);
+
+    if(FSREe_A < 0 || FSREe_B < 0 || FSREe_C < 0) {
+        // Invalid FSREe calculation
+        return false;
+    }
+
+    // Adjust FSREe for clock frequency
+    // Since FSREe is inversely proportional to fCLK,
+    // we adjust FSREe by dividing by the clock frequency ratio
+    double fCLK_ratio = static_cast<double>(1 << _clock_frequency); // fCLK_actual / fCLK_base
+
+    FSREe_A /= fCLK_ratio;
+    FSREe_B /= fCLK_ratio;
+    FSREe_C /= fCLK_ratio;
+
+    // Get NCLK from TIME_code
+    uint32_t NCLK;
+    if(_integration_time == 15) {
+        NCLK = 1024;
+    } else if(_integration_time <= 14) {
+        NCLK = 1 << (10 + _integration_time);
+    } else {
+        return false; // Invalid TIME_code
+    }
+
+    // Adjust NCLK and FSREe for Divider if enabled
+    if(_enable_divider) {
+        int divider_factor = 1 << (_divider + 1); // Divider factor is 2^(DIV + 1)
+        NCLK /= divider_factor; // Adjust NCLK
+        // Alternatively, we could adjust MRES, but adjusting NCLK is equivalent and simpler
+    }
+
+    // Calculate LSB for each channel
+    double LSB_A = FSREe_A / NCLK;
+    double LSB_B = FSREe_B / NCLK;
+    double LSB_C = FSREe_C / NCLK;
+
+    // Calculate Ee (Irradiance in µW/cm²) for each channel
+    results.uv_a = rawResults.uv_a * LSB_A;
+    results.uv_b = rawResults.uv_b * LSB_B;
+    results.uv_c = rawResults.uv_c * LSB_C;
+
+    return true;
+}
+
+// Get processed measurement results
+bool AS7331::getResults(Results& results) {
+    RawResults rawResults; // Temporary variable
+    return getResults(results, rawResults); // Call the core function
+}
+
+// Read temperature measurement (16-bit)
+bool AS7331::getTemperature(double& temperature) {
+    uint16_t temperature_raw;
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // Ensure we are in measurement mode
+    if(!setDeviceMode(DEVICE_MODE_MEASURE)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to set device mode to measurement.");
+        return false;
+    }
+
+    // Read temperature register
+    if(!readRegister16(RegMeasTemp, temperature_raw)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read temperature register from device.");
+        return false;
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    // Calculate temperature in Celsius (Datasheet p. 42)
+    temperature = temperature_raw * 0.05 - 66.9; // [°C]
+
+    return true;
+}
+
+// Check if the device is ready
+bool AS7331::deviceReady(const uint8_t& i2c_address_7bit) {
+    uint8_t i2c_address_8bit;
+
+    if(i2c_address_7bit == 0) {
+        i2c_address_8bit = _i2c_addr_8bit;
+    } else {
+        i2c_address_8bit = i2c_address_7bit << 1; // Convert 7-bit to 8-bit address
+    }
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    bool ready = furi_hal_i2c_is_device_ready(
+        &furi_hal_i2c_handle_external, i2c_address_8bit, AS7331_I2C_TIMEOUT);
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    return ready;
+}
+
+// Perform a software reset (OSR:SW_RES = 1)
+bool AS7331::reset() {
+    // Setting SW_RES to '1' triggers a software reset of the AS7331.
+    as7331_osr_reg_t osr;
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // OSR is accessible in any mode
+    if(!readOSRRegister(osr)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read OSR register from device.");
+        return false;
+    }
+
+    osr.software_reset = 1; // Set SW_RES bit
+
+    if(!writeOSRRegister(osr)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to write OSR register to reset device.");
+        return false;
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    // Update local configuration variables from device registers
+    _deviceMode = DEVICE_MODE_CONFIG;
+    if(!updateLocalConfig()) {
+        FURI_LOG_E("AS7331", "Failed to read device configuration registers.");
+        return false;
+    }
+
+    return true;
+}
+
+// Getter methods
+
+// Read device ID (including mutation number)
+bool AS7331::getDeviceID(as7331_agen_reg_t& deviceID) {
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    if(!readRegister(RegCfgAgen, deviceID.byte)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read device ID register from device.");
+        return false;
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    return true;
+}
+
+// Read status register in measurement mode
+bool AS7331::getStatus(as7331_osr_status_reg_t& status) {
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // Ensure we are in measurement mode
+    if(!setDeviceMode(DEVICE_MODE_MEASURE)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to set device mode to measurement.");
+        return false;
+    }
+
+    if(!readRegister16(RegMeasOsrStatus, status.word)) {
+        furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+        FURI_LOG_E("AS7331", "Failed to read status register from device.");
+        return false;
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    return true;
+}
+
+// Local config getter methods
+
+// Getter for gain code
+as7331_gain_t AS7331::getGain() const {
+    return _gain;
+}
+
+// Getter for actual gain value
+int16_t AS7331::getGainValue() const {
+    // Gain value is calculated using the formula: gain = 2^(11 - gain_code)
+    return 1 << (11 - _gain);
+}
+
+// Getter for integration time code
+as7331_integration_time_t AS7331::getIntegrationTime() const {
+    return _integration_time;
+}
+
+// Get conversion time in seconds
+double AS7331::getConversionTime() const {
+    // Base clock frequency is 1.024 MHz
+    double fCLK_base = 1.024e6; // Hz
+
+    // Actual clock frequency based on CCLK code
+    double fCLK = fCLK_base * (1 << _clock_frequency);
+
+    // Calculate NCLK based on TIME code
+    uint32_t NCLK; // Number of clock cycles within conversion time
+    if(_integration_time == 15) {
+        NCLK = 1024; // Special case: Same as TIME 0
+    } else if(_integration_time <= 14) {
+        NCLK = 1 << (10 + _integration_time);
+    } else {
+        // Invalid TIME code
+        return -1.0;
+    }
+
+    // Conversion time TCONV
+    double TCONV = static_cast<double>(NCLK) / fCLK; // in seconds
+
+    return TCONV;
+}
+
+// Getter for divider code
+as7331_divider_t AS7331::getDivider() const {
+    return _divider;
+}
+
+// Getter for divider enabled state
+bool AS7331::isDividerEnabled() const {
+    return _enable_divider;
+}
+
+// Getter for actual divider value
+uint8_t AS7331::getDividerValue() const {
+    // Divider value is calculated using the formula: divider = 2^(1 + divider_code)
+    uint8_t divider_value = 1 << (1 + _divider);
+    return divider_value;
+}
+
+// Getter for clock frequency code
+as7331_clock_frequency_t AS7331::getClockFrequency() const {
+    return _clock_frequency;
+}
+
+// Getter for actual clock frequency value
+double AS7331::getClockFrequencyValue() const {
+    // Clock frequency is calculated using the formula: fCLK = 1.024 * 2^clock_frequency_code (in MHz)
+    uint32_t freq_multiplier = 1 << _clock_frequency; // 2^clock_frequency_code
+    double clock_frequency_value = 1.024 * freq_multiplier; // in MHz
+    return clock_frequency_value;
+}
+
+// Getter for measurement mode
+as7331_measurement_mode_t AS7331::getMeasurementMode() const {
+    return _measurement_mode;
+}
+
+// Getter for power down state
+bool AS7331::isPowerDown() const {
+    return _power_down;
+}
+
+// Getter for standby state
+bool AS7331::isStandby() const {
+    return _standby;
+}
+
+// Internal helper methods
+
+// Set the device mode
+bool AS7331::setDeviceMode(const as7331_device_mode_t& mode) {
+    if(mode != DEVICE_MODE_CONFIG && mode != DEVICE_MODE_MEASURE) {
+        FURI_LOG_E("AS7331", "Invalid device mode value: %d.", mode);
+        return false;
+    }
+    if(_deviceMode == mode) {
+        return true; // Already in desired mode
+    }
+
+    // Read OSR register
+    as7331_osr_reg_t osr;
+    if(!readOSRRegister(osr)) {
+        FURI_LOG_E("AS7331", "Failed to read OSR register from device.");
+        return false;
+    }
+
+    // Set operating state (DOS bits)
+    osr.operating_state = mode;
+
+    // If transitioning to Measurement state, ensure power-down is disabled
+    if(mode == DEVICE_MODE_MEASURE) {
+        osr.power_down = 0;
+    }
+
+    // Write back OSR register
+    // '_deviceMode' is updated in writeOSRRegister
+    if(!writeOSRRegister(osr)) {
+        FURI_LOG_E("AS7331", "Failed to write OSR register to set device mode.");
+        return false;
+    }
+
+    return true;
+}
+
+// Read OSR register and update local config
+bool AS7331::readOSRRegister(as7331_osr_reg_t& osr) {
+    if(!readRegister(RegCfgOsr, osr.byte)) {
+        FURI_LOG_E("AS7331", "Failed to read OSR Register from device.");
+        return false;
+    }
+
+    if(osr.operating_state != DEVICE_MODE_CONFIG && osr.operating_state != DEVICE_MODE_MEASURE) {
+        FURI_LOG_E(
+            "AS7331", "Invalid operating state value read from device: %d.", osr.operating_state);
+        return false;
+    }
+
+    // Update local config
+    _deviceMode = osr.operating_state;
+    _power_down = osr.power_down;
+
+    return true;
+}
+
+// Write OSR register and update local config
+bool AS7331::writeOSRRegister(const as7331_osr_reg_t& osr) {
+    if(osr.operating_state != DEVICE_MODE_CONFIG && osr.operating_state != DEVICE_MODE_MEASURE) {
+        FURI_LOG_E("AS7331", "Invalid device mode value: %d.", osr.operating_state);
+        return false;
+    }
+
+    // Write back OSR register
+    if(!writeRegister(RegCfgOsr, osr.byte)) {
+        FURI_LOG_E("AS7331", "Failed to write OSR to device: %d.", osr.byte);
+        return false;
+    }
+
+    // Update local config
+    _deviceMode = osr.operating_state;
+    _power_down = osr.power_down;
+
+    return true;
+}
+
+// Generalized method to read multiple bytes from consecutive registers
+bool AS7331::readRegisters(uint8_t start_register_addr, uint8_t* buffer, size_t length) {
+    bool success;
+
+    // Write Phase: Send the start register address, end with AwaitRestart
+    success = furi_hal_i2c_tx_ext(
+        &furi_hal_i2c_handle_external,
+        _i2c_addr_8bit,
+        false, // 7-bit address
+        &start_register_addr,
+        1,
+        FuriHalI2cBeginStart,
+        FuriHalI2cEndAwaitRestart, // Prepare for repeated start
+        AS7331_I2C_TIMEOUT);
+    if(!success) {
+        FURI_LOG_E("AS7331", "Failed to send start register address");
+        return false;
+    }
+
+    // Read Phase: Read the data, begin with Restart, end with Stop
+    success = furi_hal_i2c_rx_ext(
+        &furi_hal_i2c_handle_external,
+        _i2c_addr_8bit,
+        false, // 7-bit address
+        buffer,
+        length,
+        FuriHalI2cBeginRestart, // Repeated start
+        FuriHalI2cEndStop,
+        AS7331_I2C_TIMEOUT);
+    if(!success) {
+        FURI_LOG_E("AS7331", "Failed to read data");
+        return false;
+    }
+
+    return true;
+}
+
+// Function to read an 8-bit register
+bool AS7331::readRegister(uint8_t register_addr, uint8_t& data) {
+    return readRegisters(register_addr, &data, 1);
+}
+
+// Function to read a 16-bit register
+bool AS7331::readRegister16(uint8_t register_addr, uint16_t& data) {
+    uint8_t buffer[2];
+    bool success = readRegisters(register_addr, buffer, 2);
+    if(!success) {
+        return false;
+    }
+
+    // Combine the two bytes into a 16-bit value (LSB first)
+    data = (static_cast<uint16_t>(buffer[1]) << 8) | buffer[0];
+
+    return true;
+}
+
+// Function to write an 8-bit register
+bool AS7331::writeRegister(uint8_t register_addr, const uint8_t& data) {
+    bool success;
+    uint8_t buffer[2] = {register_addr, data};
+
+    // Write the register address and data in one transaction
+    success = furi_hal_i2c_tx_ext(
+        &furi_hal_i2c_handle_external,
+        _i2c_addr_8bit,
+        false, // 7-bit address
+        buffer,
+        2,
+        FuriHalI2cBeginStart,
+        FuriHalI2cEndStop,
+        AS7331_I2C_TIMEOUT);
+    if(!success) {
+        FURI_LOG_E("AS7331", "Failed to write data");
+        return false;
+    }
+
+    return true;
+}
+
+// Scan I2C bus for AS7331 device
+uint8_t AS7331::scan_i2c_bus() {
+    uint8_t addr_found = 0; // Will hold the address if found
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // Iterate through possible I2C addresses
+    for(uint8_t addr_7bit = DefaultI2CAddr; addr_7bit <= QuaternaryI2CAddr; addr_7bit++) {
+        uint8_t addr_8bit = addr_7bit << 1;
+
+        // Check for device readiness
+        if(furi_hal_i2c_is_device_ready(
+               &furi_hal_i2c_handle_external, addr_8bit, AS7331_I2C_TIMEOUT)) {
+            addr_found = addr_7bit;
+            break;
+        }
+    }
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    if(addr_found == 0) {
+        FURI_LOG_E("AS7331", "No AS7331 device found on I²C bus.");
+    }
+
+    return addr_found;
+}
+
+// Update local configuration variables from device registers
+bool AS7331::updateLocalConfig() {
+    bool success = true;
+    as7331_creg1_reg_t creg1;
+    as7331_creg2_reg_t creg2;
+    as7331_creg3_reg_t creg3;
+
+    furi_hal_i2c_acquire(&furi_hal_i2c_handle_external);
+
+    // Ensure we are in configuration mode
+    success &= setDeviceMode(DEVICE_MODE_CONFIG);
+
+    // Read configuration registers
+    success &= readRegister(RegCfgCreg1, creg1.byte);
+    success &= readRegister(RegCfgCreg2, creg2.byte);
+    success &= readRegister(RegCfgCreg3, creg3.byte);
+
+    furi_hal_i2c_release(&furi_hal_i2c_handle_external);
+
+    if(!success) {
+        FURI_LOG_E("AS7331", "Failed to read configuration registers.");
+        return false;
+    }
+
+    // Validate and populate local configuration variables
+    if(creg1.gain <= GAIN_1) {
+        _gain = static_cast<as7331_gain_t>(creg1.gain);
+    } else {
+        FURI_LOG_E("AS7331", "Invalid gain value read from device: %d.", creg1.gain);
+        return false;
+    }
+
+    if(creg1.integration_time <= TIME_16384MS) {
+        _integration_time = static_cast<as7331_integration_time_t>(creg1.integration_time);
+    } else {
+        FURI_LOG_E(
+            "AS7331",
+            "Invalid integration time value read from device: %d.",
+            creg1.integration_time);
+        return false;
+    }
+
+    _enable_divider = creg2.enable_divider;
+
+    if(creg2.divider <= DIV_256) {
+        _divider = static_cast<as7331_divider_t>(creg2.divider);
+    } else {
+        FURI_LOG_E("AS7331", "Invalid divider value read from device: %d.", creg2.divider);
+        return false;
+    }
+
+    if(creg3.clock_frequency <= CCLK_8_192_MHZ) {
+        _clock_frequency = static_cast<as7331_clock_frequency_t>(creg3.clock_frequency);
+    } else {
+        FURI_LOG_E(
+            "AS7331",
+            "Invalid clock frequency value read from device: %d.",
+            creg3.clock_frequency);
+        return false;
+    }
+
+    _standby = creg3.standby;
+
+    if(creg3.measurement_mode <= MEASUREMENT_MODE_SYNC_START_END) {
+        _measurement_mode = static_cast<as7331_measurement_mode_t>(creg3.measurement_mode);
+    } else {
+        FURI_LOG_E(
+            "AS7331",
+            "Invalid measurement mode value read from device: %d.",
+            creg3.measurement_mode);
+        return false;
+    }
+
+    // _deviceMode and _power_down is updated in readOSRRegister()/writeOSRRegister()
+
+    return true;
+}
+
+/**
+ * @brief Calculates the Full-Scale Range irradiance (FSREe) for a given UV type.
+ *
+ * This function computes the FSREe, which is the maximum detectable irradiance (Ee) that the sensor can measure without saturating the ADC, based on the selected GAIN settings. Optionally, it can adjust FSREe for the integration TIME setting.
+ *
+ * **Definitions:**
+ * - **FSR (FSREe in equations)**: Full-Scale Range—the maximum detectable irradiance (Ee) the sensor can measure without saturating the ADC, given the selected GAIN (and optionally TIME) settings.
+ * - **LSB**: Least Significant Bit—the smallest change in irradiance that the sensor can detect with the selected settings. In the datasheet, it's given in nW/cm², but here we calculate it in µW/cm² (same as FSREe).
+ * - **NCLK**: Number of clock cycles during the conversion.
+ * - **MRES**: ADC count. The most straightforward way to get Ee is:
+ *   - *Ee = MRES × LSB* (ADC count times the value of a single step)
+ * - **LSB Calculation**:
+ *   - *LSB = FSR / NCLK*
+ *
+ * **Note:**
+ * - Both LSB and FSR depend on the clock frequency (fCLK); the tables in the datasheet assume an fCLK of 1.024 MHz.
+ * - When calculating LSB, FSREe should **not** be adjusted for integration TIME, as higher TIME values increase the resolution beyond 16 bits, and only the least 16 bits are stored in the result registers.
+ *
+ * @param uvType The type of UV measurement (UV_A, UV_B, or UV_C).
+ * @param adjustForIntegrationTime Optional. A boolean flag indicating whether to adjust FSREe for the integration TIME setting. Default is `true`.
+ * @return The calculated FSREe value in µW/cm², or `-1.0` if an error occurs.
+ */
+double AS7331::calculateFSREe(as7331_uv_type_t uvType, bool adjustForIntegrationTime) {
+    // Base FSREe at GAIN = 1x for each channel, from datasheet (p.32 - p.38)
+    double FSREe_gain1;
+    switch(uvType) {
+    case UV_A: // Channel A
+        FSREe_gain1 = 348160.0; // µW/cm² at GAIN=1x, TIME code 6
+        break;
+    case UV_B: // Channel B
+        FSREe_gain1 = 387072.0; // µW/cm² at GAIN=1x, TIME code 6
+        break;
+    case UV_C: // Channel C
+        FSREe_gain1 = 169984.0; // µW/cm² at GAIN=1x, TIME code 3
+        break;
+    default:
+        // Invalid UV type
+        return -1.0;
+    }
+
+    // Calculate the actual gain value
+    int GAIN_value = getGainValue();
+    if(GAIN_value <= 0) {
+        return -1.0; // Invalid GAIN
+    }
+
+    // Calculate the base FSREe for the current gain setting
+    double FSREe = FSREe_gain1 / GAIN_value;
+
+    if(adjustForIntegrationTime) {
+        // Adjust FSREe for integration TIME
+        if(uvType == UV_A || uvType == UV_B) {
+            if(_integration_time <= 6) {
+                // No adjustment needed for TIME codes 0-6
+            } else if(_integration_time <= 14) {
+                // For each TIME code above 6, FSREe halves
+                int time_diff = _integration_time - 6;
+                FSREe /= (1 << time_diff); // FSREe /= 2^(TIME_code - 6)
+            } else if(_integration_time == 15) {
+                // Special case: TIME code 15 is equivalent to TIME code 0
+                // No adjustment needed
+            } else {
+                return -1.0; // Invalid TIME code
+            }
+        } else if(uvType == UV_C) {
+            if(_integration_time <= 3) {
+                // No adjustment needed for TIME codes 0-3
+            } else if(_integration_time <= 7) {
+                // Divide FSREe by 2
+                FSREe /= 2;
+            } else if(_integration_time <= 14) {
+                // For each TIME code above 7, FSREe halves
+                int time_diff = _integration_time - 7;
+                FSREe /= (1 << time_diff); // FSREe /= 2^(TIME_code - 3)
+            } else if(_integration_time == 15) {
+                // Special case: TIME code 15 is equivalent to TIME code 0
+                // No adjustment needed
+            } else {
+                return -1.0; // Invalid TIME code
+            }
+        }
+    }
+
+    return FSREe;
+}

uv_meter_as7331/AS7331.hpp

@@ -0,0 +1,731 @@
+/**
+ * @file AS7331.hpp
+ * @brief UV Spectral Sensor - AS7331 Driver
+ *
+ * This driver provides a communication interface for the AS7331 UV spectral sensor.
+ * It includes configurations for I2C addressing, device modes, gain, clock frequency,
+ * and measurement settings.
+ *
+ * Inspired by: https://github.com/sparkfun/SparkFun_AS7331_Arduino_Library/blob/main/src/sfeAS7331.h
+ * Datasheet: https://look.ams-osram.com/m/1856fd2c69c35605/original/AS7331-Spectral-UVA-B-C-Sensor.pdf
+ */
+
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <furi_hal_i2c_types.h>
+
+/**
+ * @defgroup AS7331_I2C_Addressing I2C Addressing
+ * @brief I2C address definitions for AS7331
+ *
+ * The 7-bit I2C address is defined as [1, 1, 1, 0, 1, A1, A0], where A1 and A0 are configurable address pins.
+ * @{
+ */
+
+/** Default I2C address when A1 = 0, A0 = 0 */
+const uint8_t DefaultI2CAddr = 0x74;
+
+/** Secondary I2C address when A1 = 0, A0 = 1 */
+const uint8_t SecondaryI2CAddr = 0x75;
+
+/** Tertiary I2C address when A1 = 1, A0 = 0 */
+const uint8_t TertiaryI2CAddr = 0x76;
+
+/** Quaternary I2C address when A1 = 1, A0 = 1 */
+const uint8_t QuaternaryI2CAddr = 0x77;
+
+/** Expected API Generation Register content (Device ID + Mutation number) */
+const uint8_t ExpectedAGENContent = 0x21;
+
+/** @} */ // End of AS7331_I2C_Addressing group
+
+/**
+ * @defgroup AS7331_Enums Enumerations
+ * @brief Enumerations for AS7331 settings
+ * @{
+ */
+
+/**
+ * @brief Device Operating Modes
+ */
+enum as7331_device_mode_t : uint8_t {
+    DEVICE_MODE_CONFIG = 0x2, /**< Configuration mode */
+    DEVICE_MODE_MEASURE = 0x3 /**< Measurement mode */
+};
+
+/**
+ * @brief Sensor Gain Settings (CREG1:GAIN)
+ *
+ * Default: GAIN_2 (1010)
+ *
+ * Gain value is calculated as:  
+ * **gain = 2<sup>(11 - gain_code)</sup>**
+ */
+enum as7331_gain_t : uint8_t {
+    GAIN_2048 = 0x0000,
+    GAIN_1024,
+    GAIN_512,
+    GAIN_256,
+    GAIN_128,
+    GAIN_64,
+    GAIN_32,
+    GAIN_16,
+    GAIN_8,
+    GAIN_4,
+    GAIN_2,
+    GAIN_1
+};
+
+/**
+ * @brief Integration Time Settings (CREG1:TIME)
+ *
+ * Default: TIME_64MS (0110)
+ *
+ * The conversion time in the enumerators (in milliseconds) is valid for a clock frequency of 1.024 MHz.
+ * For higher clock frequencies, the conversion time is divided by 2 each time the clock frequency is doubled.
+ *
+ * **Conversion Time [ms] = 2<sup>integration_time_code</sup>**
+ */
+enum as7331_integration_time_t : uint8_t {
+    TIME_1MS = 0x0,
+    TIME_2MS,
+    TIME_4MS,
+    TIME_8MS,
+    TIME_16MS,
+    TIME_32MS,
+    TIME_64MS,
+    TIME_128MS,
+    TIME_256MS,
+    TIME_512MS,
+    TIME_1024MS,
+    TIME_2048MS,
+    TIME_4096MS,
+    TIME_8192MS,
+    TIME_16384MS
+};
+
+/**
+ * @brief Divider Settings (CREG2:DIV)
+ *
+ * Default: DIV_2 (000)
+ *
+ * Divider value is calculated as:  
+ * **divider = 2<sup>(1 + divider_code)</sup>**
+ */
+enum as7331_divider_t : uint8_t {
+    DIV_2 = 0x0,
+    DIV_4,
+    DIV_8,
+    DIV_16,
+    DIV_32,
+    DIV_64,
+    DIV_128,
+    DIV_256
+};
+
+/**
+ * @brief Internal Clock Frequency Settings fCLK (CREG3:CCLK)
+ *
+ * Default: CCLK_1_024_MHZ
+ *
+ * Clock frequency is calculated as:  
+ * **clock_frequency = 1.024 × 2<sup>clock_frequency_code</sup>** (in MHz)
+ */
+enum as7331_clock_frequency_t : uint8_t {
+    CCLK_1_024_MHZ = 0x00, /**< 1.024 MHz: 1 - 16384 ms (Conversion Time) */
+    CCLK_2_048_MHZ,
+    CCLK_4_096_MHZ,
+    CCLK_8_192_MHZ /**< 8.192 MHz: 0.125 - 2048 ms (Conversion Time) */
+};
+
+/**
+ * @brief Measurement Modes (CREG3:MMODE)
+ *
+ * Default: MEASUREMENT_MODE_COMMAND (01)
+ */
+enum as7331_measurement_mode_t : uint8_t {
+    MEASUREMENT_MODE_CONTINUOUS = 0x0, /**< Continuous Measurement Mode (CONT) */
+    MEASUREMENT_MODE_COMMAND, /**< Command Measurement Mode (CMD) */
+    MEASUREMENT_MODE_SYNC_START, /**< Synchronous Measurement Mode (SYNS) - externally synchronized start of measurement */
+    MEASUREMENT_MODE_SYNC_START_END /**< Synchronous Measurement Start and End Mode (SYND) - start and end of measurement are externally synchronized */
+};
+
+/** @brief UV Type Selection */
+enum as7331_uv_type_t : uint8_t {
+    UV_A,
+    UV_B,
+    UV_C
+};
+
+/** @} */ // End of AS7331_Enums group
+
+/**
+ * @defgroup AS7331_Config_Registers Configuration Register Definitions
+ * @brief Definitions for configuration registers
+ *
+ * Registers are 8 bits long and can only be accessed in the configuration mode.
+ * @{
+ */
+
+/** @brief OSR configuration register address */
+const uint8_t RegCfgOsr = 0x00;
+
+/**
+ * @brief Operational State Register (OSR) Register Layout
+ */
+typedef union {
+    struct {
+        as7331_device_mode_t
+            operating_state    : 3; /**< DOS (010) - Device Operating State (OSR[2:0]) */
+        uint8_t software_reset : 1; /**< SW_RES (0) - Software Reset (OSR[3]) */
+        uint8_t reserved       : 2; /**< Reserved, do not write (OSR[5:4]) */
+        uint8_t power_down     : 1; /**< PD (1) - Power Down (OSR[6]) */
+        uint8_t start_state    : 1; /**< SS (0) - Start State (OSR[7]) */
+    };
+    uint8_t byte;
+} as7331_osr_reg_t;
+
+/** @brief AGEN register address */
+const uint8_t RegCfgAgen = 0x02;
+
+/**
+ * @brief AGEN Register Layout
+ */
+typedef union {
+    struct {
+        uint8_t
+            mutation : 4; /**< MUT (0001) - Mutation number of control register bank. Incremented when control registers change (AGEN[3:0]) */
+        uint8_t device_id : 4; /**< DEVID (0010) - Device ID number (AGEN[7:4]) */
+    };
+    uint8_t byte;
+} as7331_agen_reg_t;
+
+/** @brief CREG1 -- Configuration Register 1 address */
+const uint8_t RegCfgCreg1 = 0x06;
+
+/**
+ * @brief CREG1 Register Layout
+ */
+typedef union {
+    struct {
+        as7331_integration_time_t
+            integration_time : 4; /**< TIME (0110) - Integration time (CREG1[3:0]) */
+        as7331_gain_t gain   : 4; /**< GAIN (1010) - Sensor gain (CREG1[7:4]) */
+    };
+    uint8_t byte;
+} as7331_creg1_reg_t;
+
+/** @brief CREG2 -- Configuration Register 2 address */
+const uint8_t RegCfgCreg2 = 0x07;
+
+/**
+ * @brief CREG2 Register Layout
+ */
+typedef union {
+    struct {
+        as7331_divider_t divider : 3; /**< DIV (000) - Divider value (CREG2[2:0]) */
+        uint8_t enable_divider   : 1; /**< EN_DIV (0) - Divider enable (CREG2[3]) */
+        uint8_t reserved         : 2; /**< Reserved, do not write (CREG2[5:4]) */
+        uint8_t
+            enable_temp : 1; /**< EN_TM (1) - Temperature measurement enable in SYND mode (CREG2[6]) */
+        uint8_t reserved1 : 1; /**< Reserved, do not write (CREG2[7]) */
+    };
+    uint8_t byte;
+} as7331_creg2_reg_t;
+
+/** @brief CREG3 -- Configuration Register 3 address */
+const uint8_t RegCfgCreg3 = 0x08;
+
+/**
+ * @brief CREG3 Register Layout
+ */
+typedef union {
+    struct {
+        as7331_clock_frequency_t
+            clock_frequency : 2; /**< CCLK (00) - Internal clock frequency (CREG3[1:0]) */
+        uint8_t reserved    : 1; /**< Reserved, do not write (CREG3[2]) */
+        uint8_t ready_mode  : 1; /**< RDYOD (0) - Ready pin mode (CREG3[3]) */
+        uint8_t standby     : 1; /**< SB (0) - Standby mode (CREG3[4]) */
+        uint8_t reserved1   : 1; /**< Reserved, do not write (CREG3[5]) */
+        as7331_measurement_mode_t
+            measurement_mode : 2; /**< MMODE (01) - Measurement mode selection (CREG3[7:6]) */
+    };
+    uint8_t byte;
+} as7331_creg3_reg_t;
+
+/** @brief BREAK register address */
+const uint8_t RegCfgBreak =
+    0x09; /**< BREAK (0x19) - Break time TBREAK between two measurements (except CMD mode) */
+
+/** @brief EDGES register address */
+const uint8_t RegCfgEdges = 0x0A; /**< EDGES (0x1) - Number of SYN falling edges */
+
+/** @brief OPTREG - Option Register address */
+const uint8_t RegCfgOptReg = 0x0B;
+
+/**
+ * @brief OPTREG Register Layout
+ */
+typedef union {
+    struct {
+        uint8_t init_idx : 1; /**< INIT_IDX (1) - I2C repeat start mode flag (OPTREG[0]) */
+        uint8_t reserved : 7; /**< Reserved, do not write (OPTREG[7:1]) */
+    };
+    uint8_t byte;
+} as7331_optreg_reg_t;
+
+/** @} */ // End of AS7331_Config_Registers group
+
+/**
+ * @defgroup AS7331_Measurement_Registers Measurement Register Definitions
+ * @brief Definitions for measurement registers
+ *
+ * Registers are 16 bits long and read-only, except for the lower byte of the OSR/STATUS register.
+ * @{
+ */
+
+/** @brief OSR/Status register address */
+const uint8_t RegMeasOsrStatus = 0x00;
+
+/**
+ * @brief OSR/STATUS Register Layout
+ */
+typedef union {
+    struct {
+        as7331_osr_reg_t osr; /**< OSR settings (lower byte) (OSRSTAT[7:0]) */
+        uint8_t power_state   : 1; /**< POWERSTATE - Power Down state (OSRSTAT[8]) */
+        uint8_t standby_state : 1; /**< STANDBYSTATE - Standby mode state (OSRSTAT[9]) */
+        uint8_t not_ready     : 1; /**< NOTREADY - Inverted ready pin state (OSRSTAT[10]) */
+        uint8_t new_data      : 1; /**< NDATA - New data available (OSRSTAT[11]) */
+        uint8_t lost_data     : 1; /**< LDATA - Data overwritten before retrieval (OSRSTAT[12]) */
+        uint8_t adc_overflow  : 1; /**< ADCOF - Overflow of ADC channel (OSRSTAT[13]) */
+        uint8_t result_overflow : 1; /**< MRESOF - Overflow of MRES1...MRES3 (OSRSTAT[14]) */
+        uint8_t
+            out_conv_overflow : 1; /**< OUTCONVOF - Overflow of internal 24-bit OUTCONV (OSRSTAT[15]) */
+    };
+    uint16_t word;
+} as7331_osr_status_reg_t;
+
+/** @brief TEMP register address (12-bit temperature, MS 4 bits are 0) */
+const uint8_t RegMeasTemp = 0x01;
+
+/** @brief MRES1 register address - Measurement Result A */
+const uint8_t RegMeasResultA = 0x02;
+
+/** @brief MRES2 register address - Measurement Result B */
+const uint8_t RegMeasResultB = 0x03;
+
+/** @brief MRES3 register address - Measurement Result C */
+const uint8_t RegMeasResultC = 0x04;
+
+/** @brief OUTCONVL register address - First 16 bits of 24-bit OUTCONV */
+const uint8_t RegMeasOutConvL = 0x05;
+
+/** @brief OUTCONVH register address - Upper 8 bits of OUTCONV, MSB is 0 */
+const uint8_t RegMeasOutConvH = 0x06;
+
+/** @} */ // End of AS7331_Measurement_Registers group
+
+/**
+ * @brief AS7331 UV Spectral Sensor Driver
+ *
+ * This class provides an interface for the AS7331 UV spectral sensor,
+ * allowing configuration and measurement.
+ */
+class AS7331 {
+public:
+    /** @brief Struct to hold raw measurement results */
+    struct RawResults {
+        uint16_t uv_a; /**< Raw measurement for UV-A channel */
+        uint16_t uv_b; /**< Raw measurement for UV-B channel */
+        uint16_t uv_c; /**< Raw measurement for UV-C channel */
+    };
+
+    /** @brief Struct to hold processed measurement results */
+    struct Results {
+        double uv_a; /**< Irradiance for UV-A in µW/cm² */
+        double uv_b; /**< Irradiance for UV-B in µW/cm² */
+        double uv_c; /**< Irradiance for UV-C in µW/cm² */
+    };
+
+    /**
+     * @brief Constructs an AS7331 sensor object
+     *
+     * @param address I2C address of the sensor (default is DefaultI2CAddr)
+     */
+    AS7331(uint8_t address = DefaultI2CAddr);
+
+    /**
+     * @brief Initialize the sensor
+     *
+     * @param address I2C address in 7-bit format. If 0x0, scan the I2C bus to find the device.
+     * @return true if initialization is successful, false otherwise
+     */
+    bool init(const uint8_t& address = 0);
+
+    // Configuration methods
+
+    /**
+     * @brief Set sensor gain (CREG1:GAIN)
+     *
+     * @param gain Gain setting from as7331_gain_t
+     * @return true if successful, false otherwise
+     */
+    bool setGain(const as7331_gain_t& gain);
+
+    /**
+     * @brief Set integration time (CREG1:TIME)
+     *
+     * @param time Integration time setting from as7331_integration_time_t
+     * @return true if successful, false otherwise
+     */
+    bool setIntegrationTime(const as7331_integration_time_t& time);
+
+    /**
+     * @brief Set output divider (CREG2:DIV)
+     *
+     * @param divider Divider setting from as7331_divider_t
+     * @param enable Enable or disable the divider
+     * @return true if successful, false otherwise
+     */
+    bool setDivider(const as7331_divider_t& divider, const bool enable = true);
+
+    /**
+     * @brief Set clock frequency (CREG3:CCLK)
+     *
+     * @param freq Clock frequency setting from as7331_clock_frequency_t
+     * @return true if successful, false otherwise
+     */
+    bool setClockFrequency(const as7331_clock_frequency_t& freq);
+
+    /**
+     * @brief Set measurement mode (CREG3:MMODE)
+     *
+     * @param mode Measurement mode setting from as7331_measurement_mode_t
+     * @return true if successful, false otherwise
+     */
+    bool setMeasurementMode(const as7331_measurement_mode_t& mode);
+
+    // Power management
+
+    /**
+     * @brief Enable or disable power-down state (OSR:PD)
+     *
+     * @param power_down true to enable power-down, false to disable
+     * @return true if successful, false otherwise
+     */
+    bool setPowerDown(const bool& power_down);
+
+    /**
+     * @brief Enable or disable standby mode (CREG3:SB)
+     *
+     * @param standby true to enable standby, false to disable
+     * @return true if successful, false otherwise
+     */
+    bool setStandby(const bool& standby);
+
+    // Measurement methods
+
+    /**
+     * @brief Start the measurement (OSR:SS = 1)
+     *
+     * @return true if successful, false otherwise
+     */
+    bool startMeasurement();
+
+    /**
+     * @brief Stop the measurement (OSR:SS = 0)
+     *
+     * @return true if successful, false otherwise
+     */
+    bool stopMeasurement();
+
+    /**
+     * @brief Wait for the measurement to complete based on conversion time
+     */
+    void waitForMeasurement();
+
+    /**
+     * @brief Get raw measurement results
+     *
+     * Before reading results, wait an appropriate amount of time for the measurement to complete (TCONV).
+     *
+     * @param rawResults Struct to hold raw measurement results
+     * @return true if successful, false otherwise
+     */
+    bool getRawResults(RawResults& rawResults);
+
+    /**
+     * @brief Get processed measurement results
+     *
+     * Before reading results, wait an appropriate amount of time for the measurement to complete (TCONV).
+     *
+     * @param results Struct to hold processed measurement results
+     * @param rawResults Struct to hold raw measurement results
+     * @return true if successful, false otherwise
+     */
+    bool getResults(Results& results, RawResults& rawResults);
+
+    /**
+     * @brief Get processed measurement results
+     *
+     * Before reading results, wait an appropriate amount of time for the measurement to complete (TCONV).
+     *
+     * @param results Struct to hold processed measurement results
+     * @return true if successful, false otherwise
+     */
+    bool getResults(Results& results);
+
+    /**
+     * @brief Get temperature measurement
+     *
+     * Before reading results, wait an appropriate amount of time for the measurement to complete (TCONV).
+     *
+     * @param temperature Temperature in degrees Celsius
+     * @return true if successful, false otherwise
+     */
+    bool getTemperature(double& temperature);
+
+    // Utility methods
+
+    /**
+     * @brief Check if the device is ready
+     *
+     * @param i2c_address_7bit I2C address in 7-bit format (default uses internal address)
+     * @return true if device is ready, false otherwise
+     */
+    bool deviceReady(const uint8_t& i2c_address_7bit = 0);
+
+    /**
+     * @brief Perform a software reset
+     *
+     * This immediately stops any running measurements and resets the device to its configuration state,
+     * with all registers reverting to their initial values.
+     *
+     * @return true if the reset was successful, false otherwise
+     */
+    bool reset();
+
+    // Getter methods
+
+    /**
+     * @brief Get device ID (including mutation number)
+     *
+     * @param deviceID Struct to hold device ID
+     * @return true if successful, false otherwise
+     */
+    bool getDeviceID(as7331_agen_reg_t& deviceID);
+
+    /**
+     * @brief Get status register in measurement mode
+     *
+     * @param status Struct to hold status register data
+     * @return true if successful, false otherwise
+     */
+    bool getStatus(as7331_osr_status_reg_t& status);
+
+    // Local config getter methods
+
+    /**
+     * @brief Get current gain setting
+     *
+     * @return Current gain setting as as7331_gain_t
+     */
+    as7331_gain_t getGain() const;
+
+    /**
+     * @brief Get actual gain value
+     *
+     * @return Gain value as integer
+     */
+    int16_t getGainValue() const;
+
+    /**
+     * @brief Get current integration time setting
+     *
+     * @return Current integration time as as7331_integration_time_t
+     */
+    as7331_integration_time_t getIntegrationTime() const;
+
+    /**
+     * @brief Get current conversion time in seconds
+     *
+     * @return Conversion time in seconds
+     */
+    double getConversionTime() const;
+
+    /**
+     * @brief Get current divider setting
+     *
+     * @return Current divider setting as as7331_divider_t
+     */
+    as7331_divider_t getDivider() const;
+
+    /**
+     * @brief Check if divider is enabled
+     *
+     * @return true if divider is enabled, false otherwise
+     */
+    bool isDividerEnabled() const;
+
+    /**
+     * @brief Get actual divider value
+     *
+     * @return Divider value as integer
+     */
+    uint8_t getDividerValue() const;
+
+    /**
+     * @brief Get current clock frequency setting
+     *
+     * @return Current clock frequency as as7331_clock_frequency_t
+     */
+    as7331_clock_frequency_t getClockFrequency() const;
+
+    /**
+     * @brief Get actual clock frequency value
+     *
+     * @return Clock frequency in MHz
+     */
+    double getClockFrequencyValue() const;
+
+    /**
+     * @brief Get current measurement mode
+     *
+     * @return Current measurement mode as as7331_measurement_mode_t
+     */
+    as7331_measurement_mode_t getMeasurementMode() const;
+
+    /**
+     * @brief Check if power-down is enabled
+     *
+     * @return true if power-down is enabled, false otherwise
+     */
+    bool isPowerDown() const;
+
+    /**
+     * @brief Check if standby mode is enabled
+     *
+     * @return true if standby is enabled, false otherwise
+     */
+    bool isStandby() const;
+
+private:
+    // Internal helper methods
+
+    /**
+     * @brief Set the device mode
+     *
+     * @param mode Device mode to set
+     * @return true if successful, false otherwise
+     */
+    bool setDeviceMode(const as7331_device_mode_t& mode);
+
+    /**
+     * @brief Read OSR register and update local config
+     *
+     * @param osr Struct to hold OSR register data
+     * @return true if successful, false otherwise
+     */
+    bool readOSRRegister(as7331_osr_reg_t& osr);
+
+    /**
+     * @brief Write OSR register and update local config
+     *
+     * @param osr OSR register data to write
+     * @return true if successful, false otherwise
+     */
+    bool writeOSRRegister(const as7331_osr_reg_t& osr);
+
+    /**
+     * @defgroup AS7331_I2C_Methods AS7331 Custom I2C Methods
+     * @brief Custom I2C read and write functions for the AS7331 sensor.
+     *
+     * These functions utilize a "repeated start" condition instead of terminating each transaction with a STOP condition, as required by the AS7331.
+     * This is achieved using `FuriHalI2cEndAwaitRestart` and `FuriHalI2cBeginRestart`, despite their documentation referring to "Clock Stretching," which the AS7331 does not support.
+     *
+     * @note The caller is responsible for calling `furi_hal_i2c_acquire` and `furi_hal_i2c_release`.
+     * @{
+     */
+
+    /**
+     * @brief Read multiple bytes from consecutive registers
+     *
+     * @param start_register_addr Starting register address
+     * @param buffer Buffer to store read data
+     * @param length Number of bytes to read
+     * @return true if successful, false otherwise
+     * @ingroup AS7331_I2C_Methods
+     */
+    bool readRegisters(uint8_t start_register_addr, uint8_t* buffer, size_t length);
+
+    /**
+     * @brief Read an 8-bit register
+     *
+     * @param register_addr Register address to read
+     * @param data Variable to store read data
+     * @return true if successful, false otherwise
+     * @ingroup AS7331_I2C_Methods
+     */
+    bool readRegister(uint8_t register_addr, uint8_t& data);
+
+    /**
+     * @brief Read a 16-bit register
+     *
+     * @param register_addr Register address to read
+     * @param data Variable to store read data
+     * @return true if successful, false otherwise
+     * @ingroup AS7331_I2C_Methods
+     */
+    bool readRegister16(uint8_t register_addr, uint16_t& data);
+
+    /**
+     * @brief Write an 8-bit register
+     *
+     * @param register_addr Register address to write
+     * @param data Data to write
+     * @return true if successful, false otherwise
+     * @ingroup AS7331_I2C_Methods
+     */
+    bool writeRegister(uint8_t register_addr, const uint8_t& data);
+
+    /** @} */ // End of AS7331_I2C_Methods group
+
+    /**
+     * @brief Scan I2C bus for AS7331 device
+     *
+     * @return Found I2C address in 7-bit format, 0 if not found
+     */
+    uint8_t scan_i2c_bus();
+
+    /**
+     * @brief Update local configuration variables from device registers
+     *
+     * @return true if successful, false otherwise
+     */
+    bool updateLocalConfig();
+
+    /**
+     * @brief Calculate Full-Scale Range (FSREe) for a given UV type
+     *
+     * @param uvType UV type (UV_A, UV_B, UV_C)
+     * @param adjustForIntegrationTime Optional. A boolean flag indicating whether to adjust FSREe for the integration TIME setting. Default is `true`.
+     * @return FSREe value in µW/cm², `-1.0` if an error occurs
+     */
+    double calculateFSREe(as7331_uv_type_t uvType, bool adjustForIntegrationTime = true);
+
+    // Private member variables
+    uint8_t _i2c_addr_8bit;
+    as7331_device_mode_t _deviceMode;
+    bool _power_down;
+    as7331_gain_t _gain; /**< Gain code (0 to 11) */
+    as7331_integration_time_t _integration_time; /**< Integration time code (0 to 15) */
+    bool _enable_divider; /**< Divider enabled (CREG2:EN_DIV) */
+    as7331_divider_t _divider; /**< Divider value (CREG2:DIV) */
+    as7331_clock_frequency_t _clock_frequency; /**< Clock frequency code (0 to 3) */
+    bool _standby;
+    as7331_measurement_mode_t _measurement_mode;
+};

uv_meter_as7331/CHANGELOG.md

@@ -0,0 +1,2 @@
+v1.0:
+Initial Release

uv_meter_as7331/DESCRIPTION.md

@@ -0,0 +1,37 @@
+# UV Meter
+
+Application designed to measure ultraviolet (UV) radiation levels using the [AS7331](https://ams-osram.com/products/sensor-solutions/ambient-light-color-spectral-proximity-sensors/ams-as7331-spectral-uv-sensor) sensor. It supports individual measurements for UV-A, UV-B, and UV-C wavelengths. The easiest way to hook everything up is to use a breakout board, such as the one from [SparkFun](https://www.sparkfun.com/sparkfun-spectral-uv-sensor-as7331-qwiic.html).
+
+
+## Wiring
+
+Connect the AS7331 sensor to your Flipper Zero via I²C:
+
+| Sensor Pin | Flipper Zero Pin   |
+|------------|--------------------|
+| **SCL**    | C0 \[pin 16\]        |
+| **SDA**    | C1 \[pin 15\]        |
+| **3V3**    | 3V3 \[pin 9\]        |
+| **GND**    | GND \[pin 11 or 18\] |
+
+By default, the application scans all possible I²C addresses for the sensor. However, you can manually set a specific address in the settings menu, accessible by pressing the **Enter** button.
+
+
+## Usage
+
+Once connected, the application automatically displays real-time UV measurements. The main screen shows individual UV-A, UV-B, and UV-C readings. Beneath the numbers you see the currently used unit (µW/cm², W/m² or mW/m²).
+
+Next to each UV reading is a small meter indicating the raw sensor value. If this value is too high or too low, a warning symbol will appear, signaling potential sensor overexposure or underexposure. This condition will probably result in unreliable measurements. Adjusting the **Gain** and **Exposure Time** settings (similar to camera ISO and shutter speed) at the bottom of the screen can help correct this.
+
+In addition to direct sensor measurements, the application provides an interpretation of this irradiance data on human safety, displayed on the right side of the screen. The time (in minutes) indicates the recommended maximum daily exposure duration during an 8-hour work shift, based on the 2024 Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) published by the [American Conference of Governmental Industrial Hygienists (ACGIH)](https://en.wikipedia.org/wiki/American_Conference_of_Governmental_Industrial_Hygienists).
+
+Since UV radiation poses greater risks to the eyes, the app includes a setting to specify whether your eyes are protected. This adjusts the maximum daily exposure duration according to ACGIH recommendations.
+
+The displayed percentages indicate how much each UV type (UV-A, UV-B, UV-C) contributes to the maximum daily exposure. This helps illustrate that higher sensor readings don't necessarily mean a greater health risk; for example, even though UV-A sensor values are typically higher, they usually contribute less to the recommended maximum exposure limit compared to UV-B or UV-C.
+
+When following the maximum daily exposure duration, the TLV/BEI guidelines ensure: “\[…\] nearly all healthy workers may be repeatedly exposed without acute adverse health effects such as erythema and photokeratitis.”
+
+
+## Disclaimer
+
+This application is provided for informational purposes only and should not be used as a sole basis for safety-critical decisions. Always follow official guidelines, regulations, and professional advice regarding UV exposure. The developer assumes no responsibility for any damages, injuries, or consequences arising from decisions or actions based on the information provided by this application.

uv_meter_as7331/LICENSE

@@ -0,0 +1,674 @@
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+the GNU General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.

uv_meter_as7331/README.md

@@ -0,0 +1,44 @@
+# UV Meter
+
+A Flipper Zero application designed to measure ultraviolet (UV) radiation levels using the [AS7331](https://ams-osram.com/products/sensor-solutions/ambient-light-color-spectral-proximity-sensors/ams-as7331-spectral-uv-sensor) sensor. It supports individual measurements for UV-A, UV-B, and UV-C wavelengths. The easiest way to hook everything up is to use a breakout board, such as the one from [SparkFun](https://www.sparkfun.com/sparkfun-spectral-uv-sensor-as7331-qwiic.html).
+
+![wiring](images/flipper_with_sensor.jpeg)
+
+## Wiring
+
+Connect the AS7331 sensor to your Flipper Zero via I²C:
+
+![wiring](screenshots/wiring.png)
+
+| Sensor Pin | Flipper Zero Pin   |
+|------------|--------------------|
+| **SCL**    | C0 [pin 16]        |
+| **SDA**    | C1 [pin 15]        |
+| **3V3**    | 3V3 [pin 9]        |
+| **GND**    | GND [pin 11 or 18] |
+
+By default, the application scans all possible I²C addresses for the sensor. However, you can manually set a specific address in the settings menu, accessible by pressing the **Enter** button.
+
+
+## Usage
+
+Once connected, the application automatically displays real-time UV measurements. The main screen shows individual UV-A, UV-B, and UV-C readings. Beneath the numbers you see the currently used unit (µW/cm², W/m² or mW/m²).
+
+![wiring](screenshots/data_1.png)
+
+Next to each UV reading is a small meter indicating the raw sensor value. If this value is too high or too low, a warning symbol will appear, signaling potential sensor overexposure or underexposure. This condition will probably result in unreliable measurements. Adjusting the **Gain** and **Exposure Time** settings (similar to camera ISO and shutter speed) at the bottom of the screen can help correct this.
+
+In addition to direct sensor measurements, the application provides an interpretation of this irradiance data on human safety, displayed on the right side of the screen. The time (in minutes) indicates the recommended maximum daily exposure duration during an 8-hour work shift, based on the 2024 Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) published by the [American Conference of Governmental Industrial Hygienists (ACGIH)](https://en.wikipedia.org/wiki/American_Conference_of_Governmental_Industrial_Hygienists).
+
+Since UV radiation poses greater risks to the eyes, the app includes a setting to specify whether your eyes are protected. This adjusts the maximum daily exposure duration according to ACGIH recommendations.
+
+The displayed percentages indicate how much each UV type (UV-A, UV-B, UV-C) contributes to the maximum daily exposure. This helps illustrate that higher sensor readings don't necessarily mean a greater health risk; for example, even though UV-A sensor values are typically higher, they usually contribute less to the recommended maximum exposure limit compared to UV-B or UV-C.
+
+When following the maximum daily exposure duration, the TLV/BEI guidelines ensure:
+
+> “[...] nearly all healthy workers may be repeatedly exposed without acute adverse health effects such as erythema and photokeratitis.”
+
+
+## Disclaimer
+
+This application is provided for informational purposes only and should not be used as a sole basis for safety-critical decisions. Always follow official guidelines, regulations, and professional advice regarding UV exposure. The developer assumes no responsibility for any damages, injuries, or consequences arising from decisions or actions based on the information provided by this application.

uv_meter_as7331/application.fam

@@ -0,0 +1,16 @@
+App(
+    appid="uv_meter_as7331",
+    name="UV Meter",
+    apptype=FlipperAppType.EXTERNAL,
+    entry_point="uv_meter_app",
+    requires=["gui"],
+    stack_size=2 * 1024,
+    fap_category="GPIO",
+    sources=["*.c*", "!documentation"],
+    fap_version="1.0",
+    fap_icon="uv_meter.png",
+    fap_description="Measure UV radiation using the AS7331 sensor",
+    fap_author="Michael Baisch",
+    fap_weburl="https://github.com/michaelbaisch/uv_meter",
+    fap_icon_assets="assets",
+)

uv_meter_as7331/scenes/uv_meter_scene.cpp

@@ -0,0 +1,30 @@
+#include "uv_meter_scene.hpp"
+
+// Generate scene on_enter handlers array
+#define ADD_SCENE(prefix, name, id) prefix##_scene_##name##_on_enter,
+void (*const uv_meter_scene_on_enter_handlers[])(void*) = {
+#include "uv_meter_scene_config.hpp"
+};
+#undef ADD_SCENE
+
+// Generate scene on_event handlers array
+#define ADD_SCENE(prefix, name, id) prefix##_scene_##name##_on_event,
+bool (*const uv_meter_scene_on_event_handlers[])(void* context, SceneManagerEvent event) = {
+#include "uv_meter_scene_config.hpp"
+};
+#undef ADD_SCENE
+
+// Generate scene on_exit handlers array
+#define ADD_SCENE(prefix, name, id) prefix##_scene_##name##_on_exit,
+void (*const uv_meter_scene_on_exit_handlers[])(void* context) = {
+#include "uv_meter_scene_config.hpp"
+};
+#undef ADD_SCENE
+
+// Initialize scene handlers configuration structure
+const SceneManagerHandlers uv_meter_scene_handlers = {
+    .on_enter_handlers = uv_meter_scene_on_enter_handlers,
+    .on_event_handlers = uv_meter_scene_on_event_handlers,
+    .on_exit_handlers = uv_meter_scene_on_exit_handlers,
+    .scene_num = UVMeterSceneNum,
+};

uv_meter_as7331/scenes/uv_meter_scene.hpp

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <gui/scene_manager.h>
+
+// Generate scene id and total number
+#define ADD_SCENE(prefix, name, id) UVMeterScene##id,
+typedef enum {
+#include "uv_meter_scene_config.hpp"
+    UVMeterSceneNum,
+} UVMeterScene;
+#undef ADD_SCENE
+
+extern const SceneManagerHandlers uv_meter_scene_handlers;
+
+// Generate scene on_enter handlers declaration
+#define ADD_SCENE(prefix, name, id) void prefix##_scene_##name##_on_enter(void*);
+#include "uv_meter_scene_config.hpp"
+#undef ADD_SCENE
+
+// Generate scene on_event handlers declaration
+#define ADD_SCENE(prefix, name, id) \
+    bool prefix##_scene_##name##_on_event(void* context, SceneManagerEvent event);
+#include "uv_meter_scene_config.hpp"
+#undef ADD_SCENE
+
+// Generate scene on_exit handlers declaration
+#define ADD_SCENE(prefix, name, id) void prefix##_scene_##name##_on_exit(void* context);
+#include "uv_meter_scene_config.hpp"
+#undef ADD_SCENE

uv_meter_as7331/scenes/uv_meter_scene_about.cpp

@@ -0,0 +1,41 @@
+#include "uv_meter_app_i.hpp"
+
+#define UV_METER_VERSION_APP FAP_VERSION
+#define UV_METER_DEVELOPER "Michael Baisch"
+#define UV_METER_GITHUB "https://github.com/michaelbaisch/uv_meter"
+#define UV_METER_NAME "\e#\e!             UV Meter             \e!\n"
+#define UV_METER_BLANK_INV "\e#\e!                                                      \e!\n"
+
+void uv_meter_scene_about_on_enter(void* context) {
+    furi_assert(context);
+    auto* app = static_cast<UVMeterApp*>(context);
+    widget_reset(app->widget);
+    FuriString* tmp_string = furi_string_alloc();
+
+    widget_add_text_box_element(
+        app->widget, 0, 0, 128, 14, AlignCenter, AlignBottom, UV_METER_BLANK_INV, false);
+    widget_add_text_box_element(
+        app->widget, 0, 2, 128, 14, AlignCenter, AlignBottom, UV_METER_NAME, false);
+    furi_string_printf(tmp_string, "\e#Information\n");
+    furi_string_cat_printf(tmp_string, "Version: %s\n", UV_METER_VERSION_APP);
+    furi_string_cat_printf(tmp_string, "Developed by: %s\n", UV_METER_DEVELOPER);
+    furi_string_cat_printf(tmp_string, "Github: %s\n\n", UV_METER_GITHUB);
+    furi_string_cat_str(tmp_string, "\e#Description\n");
+    furi_string_cat_str(tmp_string, "Measure UV radiation using\n");
+    furi_string_cat_str(tmp_string, "the AS7331 sensor.\n");
+    widget_add_text_scroll_element(app->widget, 0, 16, 128, 50, furi_string_get_cstr(tmp_string));
+
+    furi_string_free(tmp_string);
+    view_dispatcher_switch_to_view(app->view_dispatcher, UVMeterViewWidget);
+}
+
+bool uv_meter_scene_about_on_event(void* context, SceneManagerEvent event) {
+    UNUSED(context);
+    UNUSED(event);
+    return false;
+}
+void uv_meter_scene_about_on_exit(void* context) {
+    furi_assert(context);
+    auto* app = static_cast<UVMeterApp*>(context);
+    widget_reset(app->widget);
+}

uv_meter_as7331/scenes/uv_meter_scene_config.hpp

@@ -0,0 +1,5 @@
+ADD_SCENE(uv_meter, wiring, Wiring)
+ADD_SCENE(uv_meter, data, Data)
+ADD_SCENE(uv_meter, settings, Settings)
+ADD_SCENE(uv_meter, about, About)
+ADD_SCENE(uv_meter, help, Help)

uv_meter_as7331/scenes/uv_meter_scene_data.cpp

@@ -0,0 +1,116 @@
+#include "uv_meter_app_i.hpp"
+#include "uv_meter_event.hpp"
+
+#include <gui/view_dispatcher.h>
+
+/**
+ * @brief Start a new measurement
+ *
+ * Initializes a new measurement and updates the measurement state.
+ *
+ * @param app_state Pointer to the shared app_state
+ */
+static void start_measurement(UVMeterAppState* app_state) {
+    // Start measurement
+    app_state->as7331.setMeasurementMode(MEASUREMENT_MODE_COMMAND);
+    app_state->as7331.startMeasurement();
+}
+
+/**
+ * @brief Process the measurement results
+ *
+ * Retrieves the measurement results and updates the application state.
+ *
+ * @param app Pointer to the app
+ */
+static void process_measurement_results(UVMeterApp* app) {
+    if(app->app_state->as7331.getResults(app->app_state->results, app->app_state->raw_results)) {
+        FURI_LOG_D(
+            "UV_Meter Data",
+            "Irradiance UVA: %.2f µW/cm² UVB: %.2f µW/cm² UVC: %.2f µW/cm²",
+            app->app_state->results.uv_a,
+            app->app_state->results.uv_b,
+            app->app_state->results.uv_c);
+        uv_meter_data_set_results(
+            app->uv_meter_data_view, &app->app_state->results, &app->app_state->raw_results);
+    } else {
+        FURI_LOG_E("UV_Meter Data", "Failed to get measurement results");
+    }
+}
+
+static void uv_meter_scene_data_enter_settings_callback(void* context) {
+    furi_assert(context);
+    auto* app = static_cast<UVMeterApp*>(context);
+    view_dispatcher_send_custom_event(app->view_dispatcher, UVMeterCustomEventSceneEnterSettings);
+}
+
+void uv_meter_scene_data_on_enter(void* context) {
+    auto* app = static_cast<UVMeterApp*>(context);
+
+    uv_meter_update_from_sensor(app->uv_meter_data_view);
+    uv_meter_data_set_unit(app->uv_meter_data_view, app->app_state->unit);
+
+    uv_meter_data_set_enter_settings_callback(
+        app->uv_meter_data_view, uv_meter_scene_data_enter_settings_callback, app);
+
+    view_dispatcher_switch_to_view(app->view_dispatcher, UVMeterViewData);
+}
+
+bool uv_meter_scene_data_on_event(void* context, SceneManagerEvent event) {
+    furi_assert(context);
+    auto* app = static_cast<UVMeterApp*>(context);
+    bool consumed = false;
+
+    if(event.type == SceneManagerEventTypeCustom) {
+        if(event.event == UVMeterCustomEventSceneEnterSettings) {
+            scene_manager_next_scene(app->scene_manager, UVMeterSceneSettings);
+            consumed = true;
+        }
+
+    } else if(event.type == SceneManagerEventTypeTick) {
+        furi_mutex_acquire(app->app_state->as7331_mutex, FuriWaitForever);
+
+        // Check if sensor got disconnected
+        if(!app->app_state->as7331_initialized || !app->app_state->as7331.deviceReady()) {
+            app->app_state->as7331_initialized = false;
+            scene_manager_search_and_switch_to_previous_scene(
+                app->scene_manager, UVMeterSceneWiring);
+        } else {
+            // Getting the status will put sensor into measurement state
+            as7331_osr_status_reg_t status;
+            app->app_state->as7331.getStatus(status);
+            // Check if measurement is complete
+            if(status.new_data) {
+                process_measurement_results(app);
+                start_measurement(app->app_state);
+            }
+            // This happens when measurement was interrupted by changing settings
+            else if(status.osr.start_state != 1) {
+                start_measurement(app->app_state);
+            }
+            // Handle overflows
+            if(status.adc_overflow || status.result_overflow || status.out_conv_overflow) {
+                FURI_LOG_E(
+                    "UV Meter Data",
+                    "Overflow detected! ADCOF (%d) MRESOF (%d) OUTCONVOF (%d)",
+                    status.adc_overflow,
+                    status.result_overflow,
+                    status.out_conv_overflow);
+            }
+        }
+        consumed = true;
+        furi_mutex_release(app->app_state->as7331_mutex);
+
+    } else if(event.type == SceneManagerEventTypeBack) {
+        // Always quit app in data scene
+        scene_manager_stop(app->scene_manager);
+        view_dispatcher_stop(app->view_dispatcher);
+        consumed = true;
+    }
+
+    return consumed;
+}
+
+void uv_meter_scene_data_on_exit(void* context) {
+    UNUSED(context);
+}

uv_meter_as7331/scenes/uv_meter_scene_help.cpp

@@ -0,0 +1,49 @@
+#include "uv_meter_app_i.hpp"
+
+void uv_meter_scene_help_on_enter(void* context) {
+    furi_assert(context);
+    auto* app = static_cast<UVMeterApp*>(context);
+    widget_reset(app->widget);
+    FuriString* tmp_string = furi_string_alloc();
+
+    furi_string_cat_str(tmp_string, "\e#Wiring:\n");
+    furi_string_cat_str(
+        tmp_string,
+        "  SCL: 16 [C0]\n"
+        "  SDA: 15 [C1]\n"
+        "  3V3: 9 [3V3]\n"
+        "  GND: 11 or 18 [GND]\n");
+    furi_string_cat_str(tmp_string, "\e#Usage:\n");
+    furi_string_cat_str(
+        tmp_string,
+        "Main UV values shown with\n"
+        "raw value meters beside.\n"
+        "Avoid low/high warnings by\n"
+        "adjusting Gain/Exposure.\n"
+        "Right side: Max daily safe\n"
+        "UV exposure (minutes per\n"
+        "8h day).\n"
+        "Percentages indicates each\n"
+        "UV type's contribution.\n");
+    furi_string_cat_str(
+        tmp_string,
+        "\e#Disclaimer\n"
+        "Info provided as-is;\n"
+        "not liable for usage.\n");
+
+    widget_add_text_scroll_element(app->widget, 0, 0, 128, 64, furi_string_get_cstr(tmp_string));
+
+    furi_string_free(tmp_string);
+    view_dispatcher_switch_to_view(app->view_dispatcher, UVMeterViewWidget);
+}
+
+bool uv_meter_scene_help_on_event(void* context, SceneManagerEvent event) {
+    UNUSED(context);
+    UNUSED(event);
+    return false;
+}
+void uv_meter_scene_help_on_exit(void* context) {
+    furi_assert(context);
+    auto* app = static_cast<UVMeterApp*>(context);
+    widget_reset(app->widget);
+}

uv_meter_as7331/scenes/uv_meter_scene_settings.cpp

@@ -0,0 +1,105 @@
+#include "uv_meter_app_i.hpp"
+#include "uv_meter_event.hpp"
+
+static const char* i2c_addresses[] = {
+    [UVMeterI2CAddressAuto] = "Auto",
+    [UVMeterI2CAddress74] = "0x74",
+    [UVMeterI2CAddress75] = "0x75",
+    [UVMeterI2CAddress76] = "0x76",
+    [UVMeterI2CAddress77] = "0x77",
+};
+
+static const char* units[] = {
+    [UVMeterUnituW_cm_2] = "uW/cm2",
+    [UVMeterUnitW_m_2] = "W/m2",
+    [UVMeterUnitmW_m_2] = "mW/m2",
+};
+
+static void i2c_address_change_callback(VariableItem* item) {
+    UVMeterApp* app = static_cast<UVMeterApp*>(variable_item_get_context(item));
+    uint8_t index = variable_item_get_current_value_index(item);
+
+    variable_item_set_current_value_text(item, i2c_addresses[index]);
+
+    app->app_state->i2c_address = static_cast<UVMeterI2CAddress>(index);
+}
+
+static void unit_change_callback(VariableItem* item) {
+    UVMeterApp* app = static_cast<UVMeterApp*>(variable_item_get_context(item));
+    uint8_t index = variable_item_get_current_value_index(item);
+
+    variable_item_set_current_value_text(item, units[index]);
+
+    app->app_state->unit = static_cast<UVMeterUnit>(index);
+}
+
+static void enter_callback(void* context, uint32_t index) {
+    auto* app = static_cast<UVMeterApp*>(context);
+    switch(index) {
+    // Update indices when adding new setting items
+    case 2:
+        scene_manager_handle_custom_event(app->scene_manager, UVMeterCustomEventSceneEnterHelp);
+        break;
+    case 3:
+        scene_manager_handle_custom_event(app->scene_manager, UVMeterCustomEventSceneEnterAbout);
+        break;
+    default:
+        break;
+    }
+}
+
+void uv_meter_scene_settings_on_enter(void* context) {
+    auto* app = static_cast<UVMeterApp*>(context);
+    variable_item_list_reset(app->variable_item_list);
+    VariableItem* item;
+
+    item = variable_item_list_add(
+        app->variable_item_list,
+        "I2C Address",
+        COUNT_OF(i2c_addresses),
+        i2c_address_change_callback,
+        app);
+    variable_item_set_current_value_index(item, app->app_state->i2c_address);
+    variable_item_set_current_value_text(item, i2c_addresses[app->app_state->i2c_address]);
+
+    item = variable_item_list_add(
+        app->variable_item_list, "Unit", COUNT_OF(units), unit_change_callback, app);
+    variable_item_set_current_value_index(item, app->app_state->unit);
+    variable_item_set_current_value_text(item, units[app->app_state->unit]);
+
+    // Be aware when adding new items before "Help" to change index in `enter_callback()`
+    variable_item_list_add(app->variable_item_list, "Help", 0, NULL, NULL);
+    variable_item_list_add(app->variable_item_list, "About", 0, NULL, NULL);
+
+    variable_item_list_set_enter_callback(app->variable_item_list, enter_callback, app);
+
+    view_dispatcher_switch_to_view(app->view_dispatcher, UVMeterViewVariableItemList);
+}
+
+bool uv_meter_scene_settings_on_event(void* context, SceneManagerEvent event) {
+    auto* app = static_cast<UVMeterApp*>(context);
+    bool consumed = false;
+
+    switch(event.type) {
+    case SceneManagerEventTypeCustom:
+        switch(event.event) {
+        case UVMeterCustomEventSceneEnterHelp:
+            scene_manager_next_scene(app->scene_manager, UVMeterSceneHelp);
+            consumed = true;
+            break;
+        case UVMeterCustomEventSceneEnterAbout:
+            scene_manager_next_scene(app->scene_manager, UVMeterSceneAbout);
+            consumed = true;
+            break;
+        }
+        break;
+    default:
+        break;
+    }
+    return consumed;
+}
+
+void uv_meter_scene_settings_on_exit(void* context) {
+    auto* app = static_cast<UVMeterApp*>(context);
+    variable_item_list_reset(app->variable_item_list);
+}

uv_meter_as7331/scenes/uv_meter_scene_wiring.cpp

@@ -0,0 +1,87 @@
+#include "uv_meter_app_i.hpp"
+#include "uv_meter_event.hpp"
+
+static void uv_meter_scene_wiring_enter_settings_callback(void* context) {
+    furi_assert(context);
+    auto* app = static_cast<UVMeterApp*>(context);
+    view_dispatcher_send_custom_event(app->view_dispatcher, UVMeterCustomEventSceneEnterSettings);
+}
+
+void uv_meter_scene_wiring_on_enter(void* context) {
+    furi_assert(context);
+    auto* app = static_cast<UVMeterApp*>(context);
+
+    uv_meter_wiring_set_enter_settings_callback(
+        app->uv_meter_wiring_view, uv_meter_scene_wiring_enter_settings_callback, app);
+
+    view_dispatcher_switch_to_view(app->view_dispatcher, UVMeterViewWiring);
+}
+
+bool uv_meter_scene_wiring_on_event(void* context, SceneManagerEvent event) {
+    furi_assert(context);
+    auto* app = static_cast<UVMeterApp*>(context);
+    bool consumed = false;
+
+    if(event.type == SceneManagerEventTypeCustom) {
+        if(event.event == UVMeterCustomEventSceneEnterSettings) {
+            scene_manager_next_scene(app->scene_manager, UVMeterSceneSettings);
+            consumed = true;
+        }
+    } else if(event.type == SceneManagerEventTypeTick) {
+        uint32_t current_time = furi_get_tick();
+
+        // Check once per second if AS7331 sensor is available
+        if(current_time - app->app_state->last_sensor_check_timestamp >= furi_ms_to_ticks(1000)) {
+            furi_mutex_acquire(app->app_state->as7331_mutex, FuriWaitForever);
+
+            if(!app->app_state->as7331_initialized) {
+                // Initialize the sensor, also wake it up if in power down mode
+                uint8_t i2c_address = 0x0;
+                switch(app->app_state->i2c_address) {
+                case UVMeterI2CAddressAuto:
+                    break;
+                case UVMeterI2CAddress74:
+                    i2c_address = DefaultI2CAddr;
+                    break;
+                case UVMeterI2CAddress75:
+                    i2c_address = SecondaryI2CAddr;
+                    break;
+                case UVMeterI2CAddress76:
+                    i2c_address = TertiaryI2CAddr;
+                    break;
+                case UVMeterI2CAddress77:
+                    i2c_address = QuaternaryI2CAddr;
+                    break;
+                }
+                app->app_state->as7331_initialized = app->app_state->as7331.init(i2c_address);
+            }
+            if(!app->app_state->as7331_initialized || !app->app_state->as7331.deviceReady()) {
+                app->app_state->as7331_initialized = false;
+            } else {
+                // Set default Gain and Integration Time
+                app->app_state->as7331.setGain(GAIN_8);
+                app->app_state->as7331.setIntegrationTime(TIME_128MS);
+            }
+            furi_mutex_release(app->app_state->as7331_mutex);
+
+            if(app->app_state->as7331_initialized) {
+                scene_manager_next_scene(app->scene_manager, UVMeterSceneData);
+                consumed = true;
+            }
+
+            app->app_state->last_sensor_check_timestamp = current_time;
+        }
+
+    } else if(event.type == SceneManagerEventTypeBack) {
+        // Always quit app in wiring scene
+        scene_manager_stop(app->scene_manager);
+        view_dispatcher_stop(app->view_dispatcher);
+        consumed = true;
+    }
+
+    return consumed;
+}
+
+void uv_meter_scene_wiring_on_exit(void* context) {
+    UNUSED(context);
+}

uv_meter_as7331/uv_meter_app.cpp

@@ -0,0 +1,115 @@
+
+#include "uv_meter_app_i.hpp"
+
+// Forward events from View Dispatcher to Scene Manager
+static bool uv_meter_app_custom_callback(void* context, uint32_t custom_event) {
+    furi_assert(context);
+    auto* app = static_cast<UVMeterApp*>(context);
+    return scene_manager_handle_custom_event(app->scene_manager, custom_event);
+}
+
+static bool uv_meter_app_back_event_callback(void* context) {
+    furi_assert(context);
+    auto* app = static_cast<UVMeterApp*>(context);
+    bool value = scene_manager_handle_back_event(app->scene_manager);
+    return value;
+}
+
+static void uv_meter_app_tick_callback(void* context) {
+    furi_assert(context);
+    auto* app = static_cast<UVMeterApp*>(context);
+    scene_manager_handle_tick_event(app->scene_manager);
+}
+
+static UVMeterApp* uv_meter_app_alloc() {
+    UVMeterApp* app = new UVMeterApp();
+
+    app->app_state = new UVMeterAppState();
+    app->app_state->as7331_mutex = furi_mutex_alloc(FuriMutexTypeNormal);
+    app->app_state->results.uv_a = 0;
+    app->app_state->results.uv_b = 0;
+    app->app_state->results.uv_c = 0;
+    app->app_state->raw_results.uv_a = 0;
+    app->app_state->raw_results.uv_b = 0;
+    app->app_state->raw_results.uv_c = 0;
+    app->app_state->last_sensor_check_timestamp = 0;
+    app->app_state->as7331_initialized = false;
+    app->app_state->i2c_address = UVMeterI2CAddressAuto;
+    app->app_state->unit = UVMeterUnituW_cm_2;
+
+    app->scene_manager = scene_manager_alloc(&uv_meter_scene_handlers, app);
+    app->view_dispatcher = view_dispatcher_alloc();
+    view_dispatcher_set_event_callback_context(app->view_dispatcher, app);
+    view_dispatcher_set_custom_event_callback(app->view_dispatcher, uv_meter_app_custom_callback);
+    view_dispatcher_set_navigation_event_callback(
+        app->view_dispatcher, uv_meter_app_back_event_callback);
+    view_dispatcher_set_tick_event_callback(
+        app->view_dispatcher, uv_meter_app_tick_callback, furi_ms_to_ticks(150));
+
+    app->uv_meter_wiring_view = uv_meter_wiring_alloc();
+    view_dispatcher_add_view(
+        app->view_dispatcher,
+        UVMeterViewWiring,
+        uv_meter_wiring_get_view(app->uv_meter_wiring_view));
+    app->variable_item_list = variable_item_list_alloc();
+    view_dispatcher_add_view(
+        app->view_dispatcher,
+        UVMeterViewVariableItemList,
+        variable_item_list_get_view(app->variable_item_list));
+    app->uv_meter_data_view = uv_meter_data_alloc();
+    uv_meter_data_set_sensor(
+        app->uv_meter_data_view, &app->app_state->as7331, app->app_state->as7331_mutex);
+    view_dispatcher_add_view(
+        app->view_dispatcher, UVMeterViewData, uv_meter_data_get_view(app->uv_meter_data_view));
+    app->widget = widget_alloc();
+    view_dispatcher_add_view(
+        app->view_dispatcher, UVMeterViewWidget, widget_get_view(app->widget));
+
+    app->gui = static_cast<Gui*>(furi_record_open(RECORD_GUI));
+    view_dispatcher_attach_to_gui(app->view_dispatcher, app->gui, ViewDispatcherTypeFullscreen);
+    scene_manager_next_scene(app->scene_manager, UVMeterViewWiring);
+
+    return app;
+}
+
+static void uv_meter_app_free(UVMeterApp* app) {
+    furi_assert(app);
+    furi_record_close(RECORD_GUI);
+    view_dispatcher_remove_view(app->view_dispatcher, UVMeterViewWidget);
+    widget_free(app->widget);
+    view_dispatcher_remove_view(app->view_dispatcher, UVMeterViewData);
+    uv_meter_data_free(app->uv_meter_data_view);
+    view_dispatcher_remove_view(app->view_dispatcher, UVMeterViewVariableItemList);
+    variable_item_list_free(app->variable_item_list);
+    view_dispatcher_remove_view(app->view_dispatcher, UVMeterViewWiring);
+    uv_meter_wiring_free(app->uv_meter_wiring_view);
+
+    view_dispatcher_free(app->view_dispatcher);
+    scene_manager_free(app->scene_manager);
+
+    furi_mutex_free(app->app_state->as7331_mutex);
+    delete app->app_state;
+    delete app;
+}
+
+/**
+ * @brief Main application entry point
+ *
+ * @param p Unused parameter
+ * @return Exit code
+ */
+extern "C" int32_t uv_meter_app(void* p) {
+    UNUSED(p);
+    UVMeterApp* app = uv_meter_app_alloc();
+
+    view_dispatcher_run(app->view_dispatcher);
+
+    // Power down the sensor before exiting
+    if(app->app_state->as7331_initialized) {
+        app->app_state->as7331.setPowerDown(true);
+        app->app_state->as7331_initialized = false;
+    }
+
+    uv_meter_app_free(app);
+    return 0;
+}

uv_meter_as7331/uv_meter_app.hpp

@@ -0,0 +1,30 @@
+/**
+ * @file uv_meter_app.hpp
+ * @brief UV Meter Application for AS7331 UV Spectral Sensor
+ *
+ * This application interfaces with the AS7331 UV spectral sensor using I2C communication
+ * to measure UV-A, UV-B, and UV-C irradiance. The measurements are displayed on the Flipper Zero's screen.
+ *
+ * Hardware Connections:
+ * - SCL: C0 [pin 16]
+ * - SDA: C1 [pin 15]
+ * - 3V3: 3V3 [pin 9]
+ * - GND: GND [pin 11 or 18]
+ */
+#pragma once
+
+typedef struct UVMeterApp UVMeterApp;
+
+typedef enum {
+    UVMeterI2CAddressAuto,
+    UVMeterI2CAddress74,
+    UVMeterI2CAddress75,
+    UVMeterI2CAddress76,
+    UVMeterI2CAddress77,
+} UVMeterI2CAddress;
+
+typedef enum {
+    UVMeterUnituW_cm_2,
+    UVMeterUnitW_m_2,
+    UVMeterUnitmW_m_2,
+} UVMeterUnit;

uv_meter_as7331/uv_meter_app_i.hpp

@@ -0,0 +1,56 @@
+#pragma once
+
+#include "uv_meter_app.hpp"
+
+#include <gui/gui.h>
+#include <gui/view_dispatcher.h>
+#include <gui/scene_manager.h>
+#include <gui/modules/widget.h>
+#include <gui/modules/variable_item_list.h>
+
+#include <furi.h>
+#include <furi_hal.h>
+
+#include <furi_hal_gpio.h>
+#include <furi_hal_resources.h>
+
+#include "uv_meter_as7331_icons.h"
+#include "scenes/uv_meter_scene.hpp"
+#include "views/uv_meter_wiring.hpp"
+#include "views/uv_meter_data.hpp"
+#include "AS7331.hpp"
+
+// Prevent compiler optimization for debugging (remove in production).
+// #pragma GCC optimize("O0")
+
+typedef struct {
+    AS7331::Results results; /**< Processed measurement results */
+    AS7331::RawResults raw_results; /**< Raw measurement results */
+    AS7331 as7331; /**< AS7331 sensor object */
+    bool as7331_initialized; /**< Flag indicating if sensor is initialized */
+    FuriMutex* as7331_mutex; /**< Mutex for thread-safe data access */
+    uint32_t last_sensor_check_timestamp; /**< Last time sensor availability was checked */
+    // Settings
+    UVMeterI2CAddress i2c_address;
+    UVMeterUnit unit;
+} UVMeterAppState;
+
+struct UVMeterApp {
+    Gui* gui;
+    SceneManager* scene_manager;
+    ViewDispatcher* view_dispatcher;
+    // Views
+    UVMeterWiring* uv_meter_wiring_view;
+    VariableItemList* variable_item_list;
+    UVMeterData* uv_meter_data_view;
+    Widget* widget;
+
+    UVMeterAppState* app_state; /**< Shared app_state */
+};
+
+typedef enum {
+    UVMeterViewWiring,
+    UVMeterViewVariableItemList,
+    UVMeterViewData,
+    UVMeterViewWidget,
+} UVMeterView;

uv_meter_as7331/uv_meter_event.hpp

@@ -0,0 +1,7 @@
+#pragma once
+
+typedef enum {
+    UVMeterCustomEventSceneEnterHelp,
+    UVMeterCustomEventSceneEnterAbout,
+    UVMeterCustomEventSceneEnterSettings,
+} UVMeterCustomEvent;

uv_meter_as7331/views/uv_meter_data.cpp

@@ -0,0 +1,693 @@
+#include "uv_meter_data.hpp"
+
+#include <gui/elements.h>
+#include "uv_meter_as7331_icons.h"
+
+#include <locale/locale.h>
+#include <math.h>
+
+#define UV_METER_MAX_RAW_VALUE 65535.0
+
+struct UVMeterData {
+    View* view;
+    AS7331* sensor;
+    FuriMutex* sensor_mutex;
+    UVMeterDataEnterSettingsCallback callback;
+    void* context;
+};
+
+// Configuration mode states
+typedef enum {
+    UVMeterConfigModeNone, // No config selected
+    UVMeterConfigModeGain, // Configure gain
+    UVMeterConfigModeExposureTime, // Configure exposure time
+    UVMeterConfigModeEyesProtection, // Configure eyes protection mode
+} UVMeterConfigMode;
+
+typedef struct {
+    FuriString* buffer;
+    UVMeterConfigMode current_config_mode;
+    AS7331::Results results;
+    AS7331::RawResults raw_results;
+    UVMeterEffectiveResults effective_results;
+    int16_t gain_value;
+    double conversion_time;
+    bool eyes_protected;
+    UVMeterUnit unit;
+} UVMeterDataModel;
+
+static void uv_meter_data_draw_raw_meter(
+    Canvas* canvas,
+    int x,
+    int y,
+    uint16_t raw_value,
+    double max_meter_value) {
+    int meter_value = (int)lround((double)raw_value / max_meter_value * (double)8.0);
+
+    // Draw the meter frame
+    canvas_draw_frame(canvas, x, y, 3, 10);
+
+    // Draw the meter level
+    canvas_draw_line(canvas, x + 1, y + 9, x + 1, y + 9 - meter_value);
+
+    // Show alert if value is too low or at max
+    if(raw_value < 5 || raw_value >= max_meter_value) {
+        canvas_draw_icon(canvas, x + 5, y + 1, &I_Alert_9x8);
+    }
+}
+
+static void uv_meter_data_draw_uv_measurements(
+    Canvas* canvas,
+    const AS7331::Results* results,
+    const AS7331::RawResults* raw_results,
+    UVMeterUnit unit,
+    FuriString* buffer) {
+    canvas_set_font(canvas, FontSecondary);
+    int x_1_align = 0;
+    int y_uva_bottom = 9;
+    int y_uvb_bottom = 23;
+    int y_uvc_bottom = 37;
+
+    // Draw labels
+    canvas_draw_str_aligned(canvas, x_1_align, y_uva_bottom, AlignLeft, AlignBottom, "UVA:");
+    canvas_draw_str_aligned(canvas, x_1_align, y_uvb_bottom, AlignLeft, AlignBottom, "UVB:");
+    canvas_draw_str_aligned(canvas, x_1_align, y_uvc_bottom, AlignLeft, AlignBottom, "UVC:");
+
+    // Display UV measurements
+    canvas_set_font(canvas, FontPrimary);
+    int x_2_align = 51;
+
+    double multiplier = 1.0;
+    switch(unit) {
+    case UVMeterUnituW_cm_2:
+        multiplier = 1.0;
+        break;
+    case UVMeterUnitW_m_2:
+        multiplier = 0.01;
+        break;
+    case UVMeterUnitmW_m_2:
+        multiplier = 10;
+        break;
+    }
+
+    // Display UVA value
+    double uv_a = results->uv_a * multiplier;
+    furi_string_printf(buffer, "%.*f", (uv_a >= 1000 ? 0 : (uv_a >= 100 ? 1 : 2)), uv_a);
+    canvas_draw_str_aligned(
+        canvas, x_2_align, y_uva_bottom, AlignRight, AlignBottom, furi_string_get_cstr(buffer));
+
+    // Display UVB value
+    double uv_b = results->uv_b * multiplier;
+    furi_string_printf(buffer, "%.*f", (uv_b >= 1000 ? 0 : (uv_b >= 100 ? 1 : 2)), uv_b);
+    canvas_draw_str_aligned(
+        canvas, x_2_align, y_uvb_bottom, AlignRight, AlignBottom, furi_string_get_cstr(buffer));
+
+    // Display UVC value
+    double uv_c = results->uv_c * multiplier;
+    furi_string_printf(buffer, "%.*f", (uv_c >= 1000 ? 0 : (uv_c >= 100 ? 1 : 2)), uv_c);
+    canvas_draw_str_aligned(
+        canvas, x_2_align, y_uvc_bottom, AlignRight, AlignBottom, furi_string_get_cstr(buffer));
+
+    // Draw raw meters with alerts
+    int raw_meter_x = x_2_align + 3;
+
+    // UVA raw meter
+    uv_meter_data_draw_raw_meter(
+        canvas, raw_meter_x, y_uva_bottom - 9, raw_results->uv_a, UV_METER_MAX_RAW_VALUE);
+
+    // UVB raw meter
+    uv_meter_data_draw_raw_meter(
+        canvas, raw_meter_x, y_uvb_bottom - 9, raw_results->uv_b, UV_METER_MAX_RAW_VALUE);
+
+    // UVC raw meter
+    uv_meter_data_draw_raw_meter(
+        canvas, raw_meter_x, y_uvc_bottom - 9, raw_results->uv_c, UV_METER_MAX_RAW_VALUE);
+}
+
+static void uv_meter_data_draw_uv_effectiveness(
+    Canvas* canvas,
+    const UVMeterEffectiveResults* effective_results,
+    FuriString* buffer) {
+    canvas_set_font(canvas, FontSecondary);
+    int x_3_align = 94;
+    int y_uva_bottom = 9;
+    int y_uvb_bottom = 23;
+    int y_uvc_bottom = 37;
+
+    // Skip if total is zero to avoid division by zero
+    if(effective_results->uv_total_eff <= 0) {
+        return;
+    }
+
+    // UVA percentage of Maximum Daily Exposure Time
+    furi_string_printf(
+        buffer,
+        "%d%%",
+        (int)lround(effective_results->uv_a_eff / effective_results->uv_total_eff * 100));
+    canvas_draw_str_aligned(
+        canvas, x_3_align, y_uva_bottom, AlignRight, AlignBottom, furi_string_get_cstr(buffer));
+
+    // UVB percentage of Maximum Daily Exposure Time
+    furi_string_printf(
+        buffer,
+        "%d%%",
+        (int)lround(effective_results->uv_b_eff / effective_results->uv_total_eff * 100));
+    canvas_draw_str_aligned(
+        canvas, x_3_align, y_uvb_bottom, AlignRight, AlignBottom, furi_string_get_cstr(buffer));
+
+    // UVC percentage of Maximum Daily Exposure Time
+    furi_string_printf(
+        buffer,
+        "%d%%",
+        (int)lround(effective_results->uv_c_eff / effective_results->uv_total_eff * 100));
+    canvas_draw_str_aligned(
+        canvas, x_3_align, y_uvc_bottom, AlignRight, AlignBottom, furi_string_get_cstr(buffer));
+
+    // Draw separator line and arrow
+    int x_3_4 = 96;
+    canvas_draw_line(canvas, x_3_4, y_uva_bottom - 9, x_3_4, y_uvc_bottom);
+    canvas_draw_icon(canvas, x_3_4 + 1, y_uvb_bottom - 6, &I_ButtonRightSmall_3x5);
+}
+
+static void uv_meter_data_draw_maximum_daily_exposure_time(
+    Canvas* canvas,
+    double t_max,
+    FuriString* buffer) {
+    int x_center_4_4 = 112;
+    int y_uvb_bottom = 23;
+
+    // Draw sun icon
+    canvas_draw_icon(canvas, x_center_4_4 - 7, -7, &I_Sun_15x16);
+
+    // Draw "min" label
+    canvas_set_font(canvas, FontSecondary);
+    canvas_draw_str_aligned(canvas, x_center_4_4, y_uvb_bottom + 2, AlignCenter, AlignTop, "min");
+
+    // Draw max exposure time in minutes
+    canvas_set_font(canvas, FontPrimary);
+    double t_max_minutes = t_max / 60;
+    furi_string_printf(
+        buffer, "%.*f", (t_max_minutes >= 100 ? 0 : (t_max_minutes >= 10 ? 1 : 2)), t_max_minutes);
+    canvas_draw_str_aligned(
+        canvas, x_center_4_4, y_uvb_bottom, AlignCenter, AlignBottom, furi_string_get_cstr(buffer));
+}
+
+static void uv_meter_data_draw_config_section(
+    Canvas* canvas,
+    int16_t gain_value,
+    double conversion_time,
+    bool eyes_protected,
+    UVMeterUnit unit,
+    UVMeterConfigMode current_config_mode,
+    FuriString* buffer) {
+    // Draw unit
+    const Icon* icon = NULL;
+    switch(unit) {
+    case UVMeterUnituW_cm_2:
+        icon = &I_Unit_uW_cm2_34x11;
+        break;
+    case UVMeterUnitW_m_2:
+        icon = &I_Unit_W_m2_22x11;
+        break;
+    case UVMeterUnitmW_m_2:
+        icon = &I_Unit_mW_m2_28x11;
+        break;
+    }
+    int x_1_align = 0;
+    int y_conf = 52;
+    canvas_draw_icon(canvas, x_1_align, y_conf - 11, icon);
+
+    // Draw text explaining selected setting
+    canvas_set_font(canvas, FontSecondary);
+    int x_setting_right = 123;
+
+    const char* setting_string;
+    switch(current_config_mode) {
+    case UVMeterConfigModeGain:
+        setting_string = "Gain";
+        break;
+    case UVMeterConfigModeExposureTime:
+        setting_string = "Exposure Time (s)";
+        break;
+    case UVMeterConfigModeEyesProtection:
+        setting_string = "Eyes Protected";
+        break;
+    default:
+        setting_string = "";
+        break;
+    }
+
+    uint16_t text_width = canvas_string_width(canvas, setting_string);
+    canvas_draw_str_aligned(
+        canvas, x_setting_right, y_conf - 2, AlignRight, AlignBottom, setting_string);
+
+    // Navigation arrows
+    canvas_draw_icon(canvas, x_setting_right + 2, y_conf - 8, &I_ButtonRightSmall_3x5);
+    canvas_draw_icon(canvas, x_setting_right - text_width - 5, y_conf - 8, &I_ButtonLeftSmall_3x5);
+
+    // Frames/Boxes for settings
+    int setting_x_size = 33;
+    int setting_y_size = 14;
+
+    // Config button box
+    canvas_draw_rframe(canvas, 0, y_conf, setting_x_size, setting_y_size, 3);
+
+    // Gain box
+    if(current_config_mode == UVMeterConfigModeGain) {
+        canvas_draw_rbox(canvas, setting_x_size - 1, y_conf, setting_x_size, setting_y_size, 3);
+    } else {
+        canvas_draw_rframe(canvas, setting_x_size - 1, y_conf, setting_x_size, setting_y_size, 3);
+    }
+
+    // Exposure Time box
+    if(current_config_mode == UVMeterConfigModeExposureTime) {
+        canvas_draw_rbox(
+            canvas, setting_x_size * 2 - 2, y_conf, setting_x_size, setting_y_size, 3);
+    } else {
+        canvas_draw_rframe(
+            canvas, setting_x_size * 2 - 2, y_conf, setting_x_size, setting_y_size, 3);
+    }
+
+    // Eyes Protection box
+    if(current_config_mode == UVMeterConfigModeEyesProtection) {
+        canvas_draw_rbox(
+            canvas, setting_x_size * 3 - 3, y_conf, setting_x_size - 1, setting_y_size, 3);
+    } else {
+        canvas_draw_rframe(
+            canvas, setting_x_size * 3 - 3, y_conf, setting_x_size - 1, setting_y_size, 3);
+    }
+
+    // Config button
+    canvas_draw_icon(canvas, 2, y_conf + 3, &I_ButtonCenter_7x7);
+    canvas_draw_str_aligned(canvas, 11, y_conf + 3, AlignLeft, AlignTop, "Conf");
+
+    // Gain value
+    if(current_config_mode == UVMeterConfigModeGain) {
+        canvas_set_color(canvas, ColorWhite);
+    }
+    furi_string_printf(buffer, "%d", gain_value);
+    canvas_draw_str_aligned(
+        canvas,
+        setting_x_size - 1 + (setting_x_size / 2),
+        y_conf + 3,
+        AlignCenter,
+        AlignTop,
+        furi_string_get_cstr(buffer));
+    canvas_set_color(canvas, ColorBlack);
+
+    // Exposure Time value
+    if(current_config_mode == UVMeterConfigModeExposureTime) {
+        canvas_set_color(canvas, ColorWhite);
+    }
+    furi_string_printf(
+        buffer,
+        "%.*f",
+        (conversion_time >= 100 ? 1 : (conversion_time >= 10 ? 2 : 3)),
+        conversion_time);
+    canvas_draw_str_aligned(
+        canvas,
+        setting_x_size * 2 - 2 + (setting_x_size / 2),
+        y_conf + 3,
+        AlignCenter,
+        AlignTop,
+        furi_string_get_cstr(buffer));
+    canvas_set_color(canvas, ColorBlack);
+
+    // Eyes Protection
+    if(current_config_mode == UVMeterConfigModeEyesProtection) {
+        canvas_set_color(canvas, ColorWhite);
+    }
+    canvas_draw_icon(
+        canvas,
+        setting_x_size * 3 - 3 + 4,
+        y_conf + 2,
+        (eyes_protected) ? &I_Sunglasses_24x8 : &I_Glasses_24x8);
+    canvas_set_color(canvas, ColorBlack);
+}
+
+static void uv_meter_data_draw_callback(Canvas* canvas, void* model) {
+    auto* m = static_cast<UVMeterDataModel*>(model);
+    FURI_LOG_D("UV_Meter Data", "Redrawing");
+
+    // Draw UV measurements section
+    uv_meter_data_draw_uv_measurements(canvas, &m->results, &m->raw_results, m->unit, m->buffer);
+
+    // Draw UV effectiveness percentages
+    uv_meter_data_draw_uv_effectiveness(canvas, &m->effective_results, m->buffer);
+
+    // Draw maximum daily exposure time
+    uv_meter_data_draw_maximum_daily_exposure_time(canvas, m->effective_results.t_max, m->buffer);
+
+    // Draw configuration section
+    uv_meter_data_draw_config_section(
+        canvas,
+        m->gain_value,
+        m->conversion_time,
+        m->eyes_protected,
+        m->unit,
+        m->current_config_mode,
+        m->buffer);
+}
+
+static bool uv_meter_data_input_callback(InputEvent* event, void* context) {
+    auto* instance = static_cast<UVMeterData*>(context);
+
+    bool consumed = false;
+    bool setting_changed = false;
+
+    if(event->type != InputTypeShort) {
+        return false;
+    }
+
+    if(event->key == InputKeyOk) {
+        if(instance->callback) {
+            instance->callback(instance->context);
+            return true;
+        }
+        return false;
+    }
+    FURI_LOG_D("UV_Meter Data", "Update Input");
+    with_view_model_cpp(
+        instance->view,
+        UVMeterDataModel*,
+        model,
+        {
+            // Handle left/right to select config
+            if(event->key == InputKeyLeft || event->key == InputKeyRight) {
+                if(event->key == InputKeyLeft) {
+                    // Move to previous config mode
+                    switch(model->current_config_mode) {
+                    case UVMeterConfigModeNone:
+                    case UVMeterConfigModeGain:
+                        model->current_config_mode = UVMeterConfigModeEyesProtection;
+                        break;
+                    case UVMeterConfigModeExposureTime:
+                        model->current_config_mode = UVMeterConfigModeGain;
+                        break;
+                    case UVMeterConfigModeEyesProtection:
+                        model->current_config_mode = UVMeterConfigModeExposureTime;
+                        break;
+                    }
+                } else { // InputKeyRight
+                    // Move to next config mode
+                    switch(model->current_config_mode) {
+                    case UVMeterConfigModeNone:
+                    case UVMeterConfigModeGain:
+                        model->current_config_mode = UVMeterConfigModeExposureTime;
+                        break;
+                    case UVMeterConfigModeExposureTime:
+                        model->current_config_mode = UVMeterConfigModeEyesProtection;
+                        break;
+                    case UVMeterConfigModeEyesProtection:
+                        model->current_config_mode = UVMeterConfigModeGain;
+                        break;
+                    }
+                }
+                consumed = true;
+                setting_changed = true;
+            }
+
+            // Handle up/down to change selected config mode
+            else if(
+                instance->sensor && model->current_config_mode != UVMeterConfigModeNone &&
+                (event->key == InputKeyUp || event->key == InputKeyDown)) {
+                furi_mutex_acquire(instance->sensor_mutex, FuriWaitForever);
+
+                switch(model->current_config_mode) {
+                case UVMeterConfigModeGain: {
+                    // Adjust gain
+                    int current_gain = static_cast<int>(instance->sensor->getGain());
+                    int new_gain = (event->key == InputKeyUp) ? current_gain - 1 :
+                                                                current_gain + 1;
+
+                    if(new_gain >= static_cast<int>(GAIN_2048) &&
+                       new_gain <= static_cast<int>(GAIN_1)) {
+                        instance->sensor->setGain(static_cast<as7331_gain_t>(new_gain));
+                        model->gain_value = instance->sensor->getGainValue();
+                        setting_changed = true;
+                    }
+                    break;
+                }
+
+                case UVMeterConfigModeExposureTime: {
+                    // Adjust integration time
+                    int current_time = static_cast<int>(instance->sensor->getIntegrationTime());
+                    int new_time = (event->key == InputKeyUp) ? current_time + 1 :
+                                                                current_time - 1;
+
+                    if(new_time >= static_cast<int>(TIME_1MS) &&
+                       new_time <= static_cast<int>(TIME_16384MS)) {
+                        instance->sensor->setIntegrationTime(
+                            static_cast<as7331_integration_time_t>(new_time));
+                        model->conversion_time = instance->sensor->getConversionTime();
+                        setting_changed = true;
+                    }
+                    break;
+                }
+
+                case UVMeterConfigModeEyesProtection:
+                    // Toggle eyes protected
+                    model->eyes_protected = !model->eyes_protected;
+                    model->effective_results = uv_meter_data_calculate_effective_results(
+                        &model->results, model->eyes_protected);
+                    setting_changed = true;
+                    break;
+
+                default:
+                    break;
+                }
+                furi_mutex_release(instance->sensor_mutex);
+                consumed = true;
+            }
+        },
+        setting_changed);
+
+    return consumed;
+}
+
+UVMeterData* uv_meter_data_alloc(void) {
+    UVMeterData* instance = new UVMeterData();
+    instance->view = view_alloc();
+    view_allocate_model(instance->view, ViewModelTypeLocking, sizeof(UVMeterDataModel));
+    view_set_draw_callback(instance->view, uv_meter_data_draw_callback);
+    view_set_input_callback(instance->view, uv_meter_data_input_callback);
+    view_set_context(instance->view, instance);
+
+    FURI_LOG_D("UV_Meter Data", "Update Alloc");
+    with_view_model_cpp(
+        instance->view,
+        UVMeterDataModel*,
+        model,
+        {
+            model->buffer = furi_string_alloc();
+            model->current_config_mode = UVMeterConfigModeGain;
+            model->results.uv_a = 0;
+            model->results.uv_b = 0;
+            model->results.uv_c = 0;
+            model->raw_results.uv_a = 0;
+            model->raw_results.uv_b = 0;
+            model->raw_results.uv_c = 0;
+            model->effective_results.uv_a_eff = 0;
+            model->effective_results.uv_b_eff = 0;
+            model->effective_results.uv_c_eff = 0;
+            model->effective_results.uv_total_eff = 0;
+            model->effective_results.t_max = 0;
+            model->gain_value = 1;
+            model->conversion_time = 1.0;
+            model->eyes_protected = true;
+            model->unit = UVMeterUnituW_cm_2;
+        },
+        true);
+
+    return instance;
+}
+
+void uv_meter_data_free(UVMeterData* instance) {
+    furi_assert(instance);
+
+    with_view_model_cpp(
+        instance->view, UVMeterDataModel*, model, { furi_string_free(model->buffer); }, false);
+
+    view_free(instance->view);
+    delete instance;
+    // Data View is not responsible for `sensor` and `sensor_mutex`
+}
+
+void uv_meter_data_reset(UVMeterData* instance, bool update) {
+    furi_assert(instance);
+    FURI_LOG_D("UV_Meter Data", "Update Reset");
+    with_view_model_cpp(
+        instance->view,
+        UVMeterDataModel*,
+        model,
+        {
+            model->current_config_mode = UVMeterConfigModeGain;
+            model->results.uv_a = 0;
+            model->results.uv_b = 0;
+            model->results.uv_c = 0;
+            model->raw_results.uv_a = 0;
+            model->raw_results.uv_b = 0;
+            model->raw_results.uv_c = 0;
+            model->effective_results.uv_a_eff = 0;
+            model->effective_results.uv_b_eff = 0;
+            model->effective_results.uv_c_eff = 0;
+            model->effective_results.uv_total_eff = 0;
+            model->effective_results.t_max = 0;
+            model->gain_value = 1;
+            model->conversion_time = 1.0;
+            model->eyes_protected = true;
+            model->unit = UVMeterUnituW_cm_2;
+        },
+        update);
+}
+
+View* uv_meter_data_get_view(UVMeterData* instance) {
+    furi_assert(instance);
+    return instance->view;
+}
+
+void uv_meter_data_set_enter_settings_callback(
+    UVMeterData* instance,
+    UVMeterDataEnterSettingsCallback callback,
+    void* context) {
+    furi_assert(instance);
+    furi_assert(callback);
+    with_view_model_cpp(
+        instance->view,
+        UVMeterDataModel*,
+        model,
+        {
+            UNUSED(model);
+            instance->callback = callback;
+            instance->context = context;
+        },
+        false);
+}
+
+void uv_meter_data_set_sensor(UVMeterData* instance, AS7331* sensor, FuriMutex* sensor_mutex) {
+    furi_assert(instance);
+    furi_assert(sensor);
+    furi_assert(sensor_mutex);
+    with_view_model_cpp(
+        instance->view,
+        UVMeterDataModel*,
+        model,
+        {
+            UNUSED(model);
+            instance->sensor = sensor;
+            instance->sensor_mutex = sensor_mutex;
+        },
+        false);
+}
+
+void uv_meter_update_from_sensor(UVMeterData* instance) {
+    furi_assert(instance);
+    if(instance->sensor) {
+        furi_mutex_acquire(instance->sensor_mutex, FuriWaitForever);
+        FURI_LOG_D("UV_Meter Data", "Update From Sensor");
+        with_view_model_cpp(
+            instance->view,
+            UVMeterDataModel*,
+            model,
+            {
+                model->gain_value = instance->sensor->getGainValue();
+                model->conversion_time = instance->sensor->getConversionTime();
+            },
+            true);
+        furi_mutex_release(instance->sensor_mutex);
+    }
+}
+
+void uv_meter_data_set_results(
+    UVMeterData* instance,
+    const AS7331::Results* results,
+    const AS7331::RawResults* raw_results) {
+    furi_assert(instance);
+    furi_assert(results);
+    furi_assert(raw_results);
+
+    FURI_LOG_D("UV_Meter Data", "Update Set Results");
+    with_view_model_cpp(
+        instance->view,
+        UVMeterDataModel*,
+        model,
+        {
+            model->results = *results;
+            model->raw_results = *raw_results;
+            model->effective_results =
+                uv_meter_data_calculate_effective_results(&model->results, model->eyes_protected);
+        },
+        true);
+}
+
+UVMeterEffectiveResults uv_meter_data_get_effective_results(UVMeterData* instance) {
+    furi_assert(instance);
+    UVMeterEffectiveResults effective_results;
+
+    with_view_model_cpp(
+        instance->view,
+        UVMeterDataModel*,
+        model,
+        { effective_results = model->effective_results; },
+        false);
+
+    return effective_results;
+}
+
+void uv_meter_data_set_eyes_protected(UVMeterData* instance, bool eyes_protected) {
+    furi_assert(instance);
+    FURI_LOG_D("UV_Meter Data", "Update Set Eyes Protected");
+    with_view_model_cpp(
+        instance->view,
+        UVMeterDataModel*,
+        model,
+        { model->eyes_protected = eyes_protected; },
+        true);
+}
+
+bool uv_meter_data_get_eyes_protected(UVMeterData* instance) {
+    furi_assert(instance);
+    bool eyes_protected = false;
+
+    with_view_model_cpp(
+        instance->view,
+        UVMeterDataModel*,
+        model,
+        { eyes_protected = model->eyes_protected; },
+        false);
+
+    return eyes_protected;
+}
+
+void uv_meter_data_set_unit(UVMeterData* instance, UVMeterUnit unit) {
+    furi_assert(instance);
+    FURI_LOG_D("UV_Meter Data", "Update Set Unit");
+    with_view_model_cpp(instance->view, UVMeterDataModel*, model, { model->unit = unit; }, true);
+}
+
+UVMeterEffectiveResults
+    uv_meter_data_calculate_effective_results(const AS7331::Results* results, bool eyes_protected) {
+    // Weighted Spectral Effectiveness
+    double w_spectral_eff_uv_a = 0.0002824;
+    double w_spectral_eff_uv_b = 0.3814;
+    double w_spectral_eff_uv_c = 0.6047;
+
+    if(eyes_protected) { // 😎
+        // w_spectral_eff_uv_a is the same
+        w_spectral_eff_uv_b = 0.2009;
+        w_spectral_eff_uv_c = 0.2547;
+    }
+    UVMeterEffectiveResults effective_results;
+    // Effective Irradiance
+    effective_results.uv_a_eff = results->uv_a * w_spectral_eff_uv_a;
+    effective_results.uv_b_eff = results->uv_b * w_spectral_eff_uv_b;
+    effective_results.uv_c_eff = results->uv_c * w_spectral_eff_uv_c;
+    effective_results.uv_total_eff =
+        effective_results.uv_a_eff + effective_results.uv_b_eff + effective_results.uv_c_eff;
+
+    // Daily dose (seconds) based on the total effective irradiance
+    double daily_dose = 0.003; // J/cm^2
+    double uW_to_W = 1e-6;
+    effective_results.t_max = daily_dose / (effective_results.uv_total_eff * uW_to_W);
+    return effective_results;
+}

uv_meter_as7331/views/uv_meter_data.hpp

@@ -0,0 +1,46 @@
+#pragma once
+
+#include <gui/view.h>
+#include "AS7331.hpp"
+#include "uv_meter_app.hpp"
+
+typedef struct UVMeterData UVMeterData;
+typedef void (*UVMeterDataEnterSettingsCallback)(void* context);
+
+/** @brief Struct to hold effective irradiance and daily exposure time */
+typedef struct {
+    double uv_a_eff; /**< Effective UV-A Irradiance in µW/cm² */
+    double uv_b_eff; /**< Effective UV-B Irradiance in µW/cm² */
+    double uv_c_eff; /**< Effective UV-C Irradiance in µW/cm² */
+    double uv_total_eff; /**< Effective total UV Irradiance in µW/cm² */
+    double t_max; /**< Maximum Daily Exposure Time in seconds*/
+} UVMeterEffectiveResults;
+
+UVMeterData* uv_meter_data_alloc(void);
+void uv_meter_data_free(UVMeterData* instance);
+void uv_meter_data_reset(UVMeterData* instance, bool update = false);
+
+View* uv_meter_data_get_view(UVMeterData* instance);
+
+void uv_meter_data_set_enter_settings_callback(
+    UVMeterData* instance,
+    UVMeterDataEnterSettingsCallback callback,
+    void* context);
+
+// AS7331 Sensor
+void uv_meter_data_set_sensor(UVMeterData* instance, AS7331* sensor, FuriMutex* sensor_mutex);
+void uv_meter_update_from_sensor(UVMeterData* instance);
+
+// General getter and setter
+void uv_meter_data_set_results(
+    UVMeterData* instance,
+    const AS7331::Results* results,
+    const AS7331::RawResults* raw_results);
+UVMeterEffectiveResults uv_meter_data_get_effective_results(UVMeterData* instance);
+void uv_meter_data_set_eyes_protected(UVMeterData* instance, bool eyes_protected);
+bool uv_meter_data_get_eyes_protected(UVMeterData* instance);
+void uv_meter_data_set_unit(UVMeterData* instance, UVMeterUnit unit);
+
+// Helper
+UVMeterEffectiveResults
+    uv_meter_data_calculate_effective_results(const AS7331::Results* results, bool eyes_protected);

uv_meter_as7331/views/uv_meter_wiring.cpp

@@ -0,0 +1,78 @@
+#include "uv_meter_wiring.hpp"
+
+#include <gui/elements.h>
+#include "uv_meter_as7331_icons.h"
+
+#include <locale/locale.h>
+#include <math.h>
+
+#define UV_METER_MAX_RAW_VALUE 65535.0
+
+struct UVMeterWiring {
+    View* view;
+    UVMeterWiringEnterSettingsCallback callback;
+    void* context;
+    //IconAnimation* icon;
+};
+
+typedef struct {
+    IconAnimation* icon;
+} UVMeterWiringModel;
+
+static void uv_meter_wiring_draw_callback(Canvas* canvas, void* model) {
+    UNUSED(model);
+    //auto* m = static_cast<UVMeterWiringModel*>(model);
+    FURI_LOG_D("UV_Meter Wiring", "Redrawing");
+
+    canvas_draw_icon(canvas, 0, 0, &I_Wiring_128x64);
+}
+
+static bool uv_meter_wiring_input_callback(InputEvent* event, void* context) {
+    auto* instance = static_cast<UVMeterWiring*>(context);
+    bool consumed = false;
+
+    if(event->key == InputKeyOk && event->type == InputTypeShort && instance->callback) {
+        instance->callback(instance->context);
+        consumed = true;
+    }
+    return consumed;
+}
+
+UVMeterWiring* uv_meter_wiring_alloc(void) {
+    UVMeterWiring* instance = new UVMeterWiring();
+    instance->view = view_alloc();
+    view_allocate_model(instance->view, ViewModelTypeLocking, sizeof(UVMeterWiringModel));
+    view_set_draw_callback(instance->view, uv_meter_wiring_draw_callback);
+    view_set_input_callback(instance->view, uv_meter_wiring_input_callback);
+    view_set_context(instance->view, instance);
+    return instance;
+}
+
+void uv_meter_wiring_free(UVMeterWiring* instance) {
+    furi_assert(instance);
+    view_free(instance->view);
+    delete instance;
+}
+
+View* uv_meter_wiring_get_view(UVMeterWiring* instance) {
+    furi_assert(instance);
+    return instance->view;
+}
+
+void uv_meter_wiring_set_enter_settings_callback(
+    UVMeterWiring* instance,
+    UVMeterWiringEnterSettingsCallback callback,
+    void* context) {
+    furi_assert(instance);
+    furi_assert(callback);
+    with_view_model_cpp(
+        instance->view,
+        UVMeterWiringModel*,
+        model,
+        {
+            UNUSED(model);
+            instance->callback = callback;
+            instance->context = context;
+        },
+        false);
+}

uv_meter_as7331/views/uv_meter_wiring.hpp

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <gui/view.h>
+
+typedef struct UVMeterWiring UVMeterWiring;
+typedef void (*UVMeterWiringEnterSettingsCallback)(void* context);
+
+UVMeterWiring* uv_meter_wiring_alloc(void);
+void uv_meter_wiring_free(UVMeterWiring* instance);
+View* uv_meter_wiring_get_view(UVMeterWiring* instance);
+
+void uv_meter_wiring_set_enter_settings_callback(
+    UVMeterWiring* instance,
+    UVMeterWiringEnterSettingsCallback callback,
+    void* context);