#include "stm32f0xx_conf.h" void SysTick_Handler(void) { static uint16_t tick = 0; switch (tick++) { case 100: tick = 0; GPIOC->ODR ^= (1 << 8); break; } } int main(void) { RCC->AHBENR |= RCC_AHBENR_GPIOCEN; // enable the clock to GPIOC //(RM0091 lists this as IOPCEN, not GPIOCEN) RCC->APB1ENR |= RCC_APB1ENR_TIM2EN; // enable TIM2 clock GPIOC->MODER = (1 << 16); SysTick_Config(SystemCoreClock/100); while(1); }