Multiple interrupts on STM32F-Discovery

Hi,

Newbie trying to make multiple interrupts work! I have been playing with the STM32-Discovery board and I am trying to make multiple interrupt handlers work at the same time. I am able to execute one interrupt, but I can’t get others to work.

The first interrupt handler is based on the blue button (PA0) (Code: see ButtonInit() in http://www.embedds.com/stm32-interrupts-and-programming-with-gcc/ ); it works great!

I want an other interrupt line and so I have picked PA4 and I have made the following changes:

void newInterrupt()
{
  //EXTI structure to init EXT
  EXTI_InitTypeDef EXTI_InitStructure;

  //NVIC structure to set up NVIC controller
  NVIC_InitTypeDef NVIC_InitStructure;

  //Connect EXTI Line to Button Pin
  GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource4); // <------ CHANGE 1

  //Configure Button EXTI line
  EXTI_InitStructure.EXTI_Line = EXTI_Line4;                  // <------ CHANGE 2

  //select interrupt mode
  EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;

  //generate interrupt on rising edge
  EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;

  //enable EXTI line
  EXTI_InitStructure.EXTI_LineCmd = ENABLE;

  //send values to registers
  EXTI_Init(&EXTI_InitStructure);

  //configure NVIC
  //select NVIC channel to configure
  NVIC_InitStructure.NVIC_IRQChannel = EXTI1_IRQn;            //<------- CHANGE 3

  //set priority to lowest
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0F;

  //set subpriority to lowest
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F;

  //enable IRQ channel
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

  //update NVIC registers
  NVIC_Init(&NVIC_InitStructure);
}

I made 3 changes (see above) and I can’t get it to work. If I understand the interrupt mechanism correctly, PA4 maps to EXTI4; whose signal is mapped onto the “EXTI1_IRQn” line because EXTI4 resides on AFIO_EXTOCR2 (EXTI0 resides on AFIO_EXTOCR1 and so its EXTI0_IRQn... the example sticks to this and it works). Is my understanding correct? Whats wrong with the above code and how can I make it work. Any suggestions are highly appreciated.

Thanks,
Pradeep