flipperzero-firmware/wiki/examples/Blink-app.md

First, let's create a simple led blinking application.

Preparing for launch

We will use integrated LED. Look at the schematic:

This led connect between power rail and GPIO PA8 and we should configure this pin as open drain to properly control led behaviour.

You can find GPIO API in target_*/flipper_hal.h. Or if you prefer to use Arduino API, you can find bindings in core/flipper.h.

For work with pin we should:

1. Create GpioPin instance and specify pin and port.
2. Configure mode of pin by pinMode function.
3. Control state of pin by digitalWrite function.

Creating application

1. Create new file (for example, blink.c) in applications folder.
2. Create code like this:

#include "flipper.h"

void application_blink(void* p) {
    // create pin
    GpioPin led = {.pin = GPIO_PIN_8, .port = GPIOA};

    // configure pin
    pinMode(led, GpioModeOutput);

    while(1) {
        digitalWrite(led, HIGH);
        delay(500);
        digitalWrite(led, LOW);
        delay(500);
    }
}

3. To start your application on Flipper startup, add it to autorun:

   • in applications/startup.h add prototype of main application function:

   void application_blink(void* p);
   

   • add entry to FLIPPER_STARTUP array (pointer to application function and application name):

   const FlipperStartupApp FLIPPER_STARTUP[] = {
       #ifdef TEST
       {.app = flipper_test_app, .name = "test app"}
       #endif
   
       // user applications:
   
       , {.app = application_blink, .name = "blink"}  
   };
   

4. Add your application file to Makefile (for each target, target_lo/Makefile and target_f1/Makefile, we add one common makefile later):

# User application

C_SOURCES += ../applications/blink.c

Build and run for linux (target_lo):

docker-compose exec dev make -C target_lo

Run:

docker-compose exec dev target_lo/build/target_lo.

Linux version has no LED or GPIO, but we can see debug messages how state of GPIO is changing:

You also run found source of this example in applications/examples/blink.c and run by docker-compose exec dev make -C target_lo example_blink