STM32 Tutorial 001a: Blinking a led

blink001.C

/*************************************** STM32 Tutorial v.2015
  Authors:   Julio Alexander Aguilar Angulo.  [email protected]
             Elodie Pauly.    [email protected]
             
  (c) ISEN-TOULON.   2015.    www.isen.fr
*******************************************************************************/
/**** Tuto 01a: Blinking a LED (and using registers and bit masking )**********/
/******************************************************************************/
#include "stm32l1xx.h" // prototypes and intrinsic declarations 
/* Testboard:  STM32L152 NUCLEO */
/**** Hardware to use on this Tutorial:  Onboard USER LED ( on PA5 ) **********/
#define LED 1<<5;  //  Mask to map that LED

/***  Variable declarations   ************************************************/
  int i;

/* Private function prototypes -----------------------------------------------*/
void Initsyst(void);
/* Code Starts Here!!  ********************************************************/
/* note: iar internals configure the system clock to 32 MHz                   */
void main()
{
  Initsyst();
  GPIOA->ODR &= ~LED;//  turn off led as initial condition
  while (1)
  {
      GPIOA->ODR^=LED;  // blink the led
      for(i=0;i<=100000;i++) // Software Delay
      {
      }
  }
}
/***** Private Functions Definition **********************************/
void Initsyst(void)
{
  RCC->AHBENR|=0x01;// affect clock to GPIOA
  GPIOA->MODER|=0x5555;// output mode
  GPIOA->OTYPER&=0x0000; // push pull
  GPIOA->OSPEEDR|=0xFFFF;// High speed out
  GPIOA->PUPDR&=0x0000; // no pullup
}