STM32L152 EXTI problem

[garciavictor]

Posted on November 27, 2011 at 19:47

Hi all.

First of all excuse my english

I am trying to implement the EXTI library but I am doing something wrong.

The program starts and send 0 by the uart (at this point all ok), then whait for a external interrupt with PA0 falling edgue (checked with the oscilloscope and its ok)

I dont know if the flag is reset or not, after applying the external interrupt the program not answered.

This is the code:

#include ''stm32l1xx.h''                 

#include <stdio.h>

GPIO_InitTypeDef  GPIO_InitStructure;

USART_InitTypeDef  USART_InitStructure; EXTI_InitTypeDef  EXTI_InitStructure; NVIC_InitTypeDef  NVIC_InitStructure;

uint8_t CONT=0x00;

int main (void){

///UART CONFIGURATION////////////////////////////////////

 RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);

 RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);

 GPIO_PinAFConfig(GPIOA, 2, GPIO_AF_USART2);

 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;

   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_40MHz;  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_DOWN;  GPIO_Init(GPIOA, &GPIO_InitStructure);

 USART_InitStructure.USART_BaudRate = 115200;

 USART_InitStructure.USART_WordLength = USART_WordLength_8b;  USART_InitStructure.USART_StopBits = USART_StopBits_1;  USART_InitStructure.USART_Parity = USART_Parity_No ;  USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;  USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;  USART_Init(USART2, &USART_InitStructure);  USART_Cmd(USART2, ENABLE);

///EXTI CONFIGURATION//////////////////////////////

 RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);

 RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);

 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;

   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;  GPIO_Init(GPIOA, &GPIO_InitStructure);    SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA, EXTI_PinSource0);

 EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;

 EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;  EXTI_InitStructure.EXTI_Line = EXTI_Line0;  EXTI_InitStructure.EXTI_LineCmd = ENABLE;  EXTI_Init(&EXTI_InitStructure);

 EXTI_ClearITPendingBit(EXTI_Line0);

 NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn;

    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0F;     NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F;     NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;     NVIC_Init(&NVIC_InitStructure);

 USART_SendData(USART2, 0x30);

 while (1)

  {

  if (EXTI_GetITStatus(EXTI_Line0)== SET){

   EXTI_ClearITPendingBit(EXTI_Line0);    EXTI_ClearFlag(EXTI_Line0);    USART_SendData(USART2, CONT);    CONT++;    }   }

}

I hope you can help me.

Thanks in advance and best regards

[Tesla DeLorean]

Posted on November 27, 2011 at 22:20

If you are generating interrupts, you'd better service them in their interrupt handler, and not in a loop in main().

Failing to clear the interrupt flag within the interrupt service will result in the M3 being stuck endlessly in interrupt context, and no foreground code will execute.

[garciavictor]

Posted on December 01, 2011 at 10:25

Hi clive, thanks a lot for the advice, I used the irqhandler and it is running.

I did use loop to simplify but finally was an error Regards