How to know if interrupt was triggered by Falling or Rising edge?

[jvilaca]

Posted on May 02, 2012 at 02:51

Hi,

If while configuring the EXTI line I use:

EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising_Falling

how can I know in my interrupt if a rising of falling triggered it?

void EXTI1_IRQHandler(void)

{

  if ( RisingEdge )

  {...}

  else if ( FallingEdge )

  { ....

   }}

How can I do anything similar to this?

Thank you for your time

[frankmeyer9]

Posted on May 02, 2012 at 16:36

I think - naturally not.

The Ref. Manual says:

Rising and falling edge triggers can be set for the same interrupt line. In this configuration, both generate a trigger condition.

This is what you do. Within the interrupt, you just know a transition happened. You could poll the current state of the line that generated it. If you are not too late, it might have been the transition to this level.

[edgarmedina20]

Posted on May 23, 2014 at 23:23

I have a similar problem, I used the IF inside the ''void EXTI0_IRQHandler(void)'' but it's not work, any idea?

void EXTI0_IRQHandler(void)

{

Delay_ms(10);//button PA0 stm32f4 discovery

if(EXTI_GetITStatus(EXTI_Line0) != SET)

{

GPIO_ResetBits(GPIOD, GPIO_Pin_13);

}

else

{

GPIO_

S

etBits(GPIOD, GPIO_Pin_13);

}

/* Clear the EXTI line 0 pending bit */

EXTI_ClearITPendingBit(EXTI_Line0);

}

[Tesla DeLorean]

Posted on May 23, 2014 at 23:42

a) You are testing an Interrupt status not a pin level

b) You are causing a race condition in the NVIC by placing the interrupt clearing as the last function, which will most likely cause immediate re-entry of the IRQ handler with the IT status as false.

[edgarmedina20]

Posted on May 24, 2014 at 00:12

ok, the questions are:

a) if I'm reading the status of interrupt, mmm... then I would have to read a status pin level, for select if a rising edge or falling edge. is it correct?

b) ok, then if I push the button, will the led turn on? and then will the led turn off? something like that. all that in one push of the button.

[Andrew Neil]

Posted on May 24, 2014 at 20:34

''I would have to read a status pin level, for select if a rising edge or falling edge. is it correct?''

Yes.

''then if I push the button''

What button? The chip doesn't know about ''buttons'' - just the levels on its input pins.

''will the led turn on?''

What LED? Again, the chip doesn't know about ''LEDs'' - it just has output pins which can be set 'high' or 'low'

[edgarmedina20]

Posted on May 24, 2014 at 21:09

thank you so much.

I learned much, including the aclaration about the chip.

[Tesla DeLorean]

Posted on May 25, 2014 at 00:34

void EXTI0_IRQHandler(void)
{
if (EXTI_GetITStatus(EXTI_Line0) != RESET)
{
/* Clear the EXTI line 0 pending bit */
EXTI_ClearITPendingBit(EXTI_Line0);
if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0))
GPIO_ResetBits(GPIOD, GPIO_Pin_13);
else
GPIO_SetBits(GPIOD, GPIO_Pin_13);
}
}

[hwang]

Posted on September 11, 2014 at 06:51

I use

void EXTI0_IRQHandler(void)

{

  if(GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0)) {

// falling

  } else {

// rising

  }}

[RafaelSTM32]

you need to be sure there are not bounce in your inputs to do that