Minimal STM32 HardwareTimer PlatformIO / Arduino timer interrupt blink example

This is a minimal example of using timer interrupts on PlatformIO / Arduino using HardwareTimer (which is a part of the PlatformIO STM32 Arduino installation - no need to install a library). Tested on the Olimex E407 board. It will run on almost any STM32 processor but you might need to adjust PC13 to the PIN connected to the LED. The example will blink the LED once per second.

#include <Arduino.h>

HardwareTimer timer(TIM1);
bool ledOn = false;

void OnTimer1Interrupt() {
    ledOn = !ledOn;
    digitalWrite(PC13, ledOn ? HIGH : LOW);
}

void setup() {
    pinMode(PC13, OUTPUT);
    // Configure timer
    timer.setPrescaleFactor(2564); // Set prescaler to 2564 => timer frequency = 168MHz/2564 = 65522 Hz (from prediv'd by 1 clocksource of 168 MHz)
    timer.setOverflow(32761); // Set overflow to 32761 => timer frequency = 65522 Hz / 32761 = 2 Hz
    timer.attachInterrupt(OnTimer1Interrupt);
    timer.refresh(); // Make register changes take effect
    timer.resume(); // Start
}

void loop() {
}