u8g2-copy/sys/arm/stm32l031x6/blink/main.c

#include "stm32l031xx.h"

int main()
{
  //RCC->CFGR &= 
  RCC->IOPENR |= RCC_IOPENR_IOPAEN;		/* Enable clock for GPIO Port A */
  __NOP();
  RCC->IOPRSTR |= RCC_IOPRSTR_IOPARST;	/* reset GPIO Port A */
  __NOP();
  
  GPIOA->MODER &= ~GPIO_MODER_MODE13;	/* clear mode for PA13 */
  GPIOA->MODER |= GPIO_MODER_MODE13_1;	/* Output mode for PA13 */
  GPIOA->OTYPER &= ~GPIO_OTYPER_OT_13;	/* no Push/Pull for PA13 */
  GPIOA->OSPEEDR &= ~GPIO_OSPEEDER_OSPEED13;	/* low speed for PA13 */
  GPIOA->PUPDR &= ~GPIO_PUPDR_PUPD13;	/* no pullup/pulldown for PA13 */
  //GPIOA->BSRR = GPIO_BSRR_BS_13;		/* atomic set PA13 */
  GPIOA->BSRR = GPIO_BSRR_BR_13;		/* atomic clr PA13 */
  
  for(;;)
    ;
}