STM32 Tutorial 001b: Using Buttons

button01.c

/*************************************** STM32 Tutorial v.2015
  Authors:   Julio Alexander Aguilar Angulo.  [email protected]
             Elodie Pauly.    [email protected]
             
  (c) ISEN-TOULON.   2015.    www.isen.fr/toulon/
*******************************************************************************/
/**** Tuto 001b: Using Buttons **********/
/******************************************************************************/
#include "stm32l1xx.h" // prototypes and intrinsic declarations 
/* Testboard:  STM32L152 NUCLEO */
/******* Hardware to use on this Tutorial:  Onboard Led and Button ***********/
//------ User Button => PC13      User Led  =>  PA5
/***  Variable declarations   ************************************************/
const uint16_t myLed = 1<<5;
const uint16_t myButton= 1<<13;

int i,j,tmp;
void Initsyst(void);
/* Code Starts Here!!  ********************************************************/
/* note: iar internals configure the system clock to 32 MHz                   */
void main()
{
  Initsyst();
  GPIOA->ODR &= ~myLed;//  turn off led as initial condition
  while (1)
  {
      tmp=GPIOC->IDR & myButton;
      if (tmp==myButton)
      {
      GPIOA->ODR &=myLed;  // do nothing
      }
      else
      {
      GPIOA->ODR ^=myLed;  // blink the led
      j=200000;   
      for(i=0;i<=j;i++) // debounce using Software Delay
      {
      }
      }
  }
}
/***** Private Functions Definition **********************************/
void Initsyst(void)
{
  RCC->AHBENR|=0x05;// affect clock to GPIOA,C  ( xxxxxxxxxxxx101)
  GPIOA->MODER|=0x5555;// output mode
  GPIOA->OTYPER&=0x0000; // push pull
  GPIOA->OSPEEDR|=0xFFFF;// High speed out
  GPIOA->PUPDR&=0x0000; // no pullup
  GPIOC->MODER&= 0x0000;// userbtn input mode
  GPIOC->PUPDR&=0x0000; // no pullup
}