identify the PORT generating an EXTI

[dbilancione]

Posted on July 14, 2013 at 15:10

dear all,

   I hope this finds you well. I am relatively new to such technology and I am working on some drivers. The board I am using has 4 LEDs, a joystick and a couple of buttons (WAKEUP and USER). I have implemented a simple program where I was polling the state of the joystick and the push-buttons and switching LEDs ON and OFF. The next step was to modify the program and use interrupts to switch LEDs instead, according to the push-button/the joystick pin pressed.

The LEFT joystick pin is connected to PC0 whereas the WAKEUP button to PA0. These are multiplexed on EXTI_LINE0. I have swiftly looked in the reference manual but I could not find a way to identify the port which is generating the interrupt on EXTI_LINE0. Is there a way to check that?

thank you!

#stm32f4 #exti #gpio

[Tesla DeLorean]

Posted on July 14, 2013 at 15:29

Well not really, the multiplexing is not something that's actively supported, because the results can be indeterminable.

Your only option is to look at the current state of the pins.

[dbilancione]

Posted on July 14, 2013 at 15:41

thank you for the swift reply clive! that is what I thought but I was hoping for a better option.

regards

[dbilancione]

Posted on July 14, 2013 at 16:30

hey clive. I have tried what you suggest but I am having an issue ... basically, if I initialize the LEFT button first then the WAKEUP button (using a function similar to the one available in the STM32F4DISCOVERY utilities) the interrupt is triggered by the WAKEUP button only; if, on the other hand, I initialize the WAKEUP button first then the LEFT button the interrupt is triggered by the LEFT button only. any idea of what the cause of that might be?

thank you

[Tesla DeLorean]

Posted on July 14, 2013 at 17:59

Well I suspect EXTICR via SYSCFG_EXTILineConfig() thwarts your ability to drive EXTI0 from TWO GPIO banks at the same time.

[dbilancione]

Posted on July 14, 2013 at 21:34

that's sensible. all of a sudden, the core is not working properly as it used to. I am trying to generate these interrupts - the idea would be to test them all - but I have started with one and it worked (WAKEUP button). moved on to two but the processor only serves one - the one triggered by the WAKEUP button whereas it never reaches the IRQHandler for the USER button (they are on different EXTI_Lines). any idea what might be causing that?

Thank you!

[Tesla DeLorean]

Posted on July 14, 2013 at 23:00

Likely something with the code which I can't see. Are you sure you have the right IRQHandler name, and that you are clearing the right source?

[dbilancione]

Posted on July 15, 2013 at 04:03

you nailed it! I missed the second underscore for the EXTI15_10_IRQn and the EXTI9_5_IRQn.

thank you ever so much! you've been extremely helpful!!!