In this article we create few application, interact between apps, use OS functions and interact with HAL.

General agreements

Flipper application is just a function:

void application_name(void* p) {
    // Setup

    while(1) {
        // Loop
    }
}

void* p is arbitrary pointer that may be used for pass parameters to application at launch (like argc/argv in POSIX).
Application must never attempt to return or exit from their implementing function.
Avoid long cycles without any "waits" or "blocking" like delay or xQueueReceive, otherwise your app will blocking overall Flipper work.
Do not create static variables inside function or global variables. Use only local variables. We plan to add virual in-RAM filesystem to save any persistent data.

Application examples

Blink show how to create app and control GPIO
UART write operate with FURI pipe and print some messages
Inter-process communication describes how to interact between application through FURI