This is a simple program that blinks a led on an ATMega644 AVR microcontroller, a classic first application used a lot as a sort of hello world in embedded C: #include <avr/io.h> #include <util/delay.h> #define LED 0 #define HEADER_SIZE 24 const uint8_t header[HEADER_SIZE] __attribute__((section(".metadata"))); int main(void) { DDRA = (1U << LED); PORTA = (0U << LED); for(;;) { PORTA ^= (1U << LED); _delay_ms(2000); } } The needs of the application I need this application to be updated via some sort of OTA/OTW update process.