/*
 STM32-ST-Link
 made on 29 Jan 2022
 by Amir Mohammad Shojaee @ Electropeak
 Home
*/

#define LED PC13 // We use the Blue Pill’s on-board LED connected to pin PC13 for the Blink program. 

// the setup function runs once when you press reset or power the board
void setup() {
 // initialize digital pin LED_BUILTIN as an output.
 pinMode(LED, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
 digitalWrite(LED, HIGH); // turn the LED on (HIGH is the voltage level)
 delay(1000); // wait for a second
 digitalWrite(LED, LOW); // turn the LED off by making the voltage LOW
 delay(1000); // wait for a second
} // As you can see, the on-board LED connected to pin PC13 starts blinking after the program is uploaded. Also, by changing this delay time, the blinking frequency changes.