GPIO extra interrupt in STM32

Question

I see in STM32F103 series, the GPIO extra interrupt is set to the EXTI. And GPIOx_0 (x=A,B,C...)is set to EXTI0. Take an example, if I want to use PA0 and PB0 as interrupt input,can I set them to EXTI0 at the same time? I mean in the EXTI0_Handler function I read the value of the input register of PA0 and PB0 to judge which one input a electrical level I want to carry different function by using if...else. I use it in STM8 successfully but there seems a little problem in STM32. Can you help me? Thanks.

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The answer explains the problem clearly. The picture takes an example that why the four bits will be changed if you set different pins. You can see that the four bit affect by each other status if you config other pins. I ignore this problem before.

Answer 1

If you look into the STM32F103 Reference Manual p. 209, you will see that there is actually a multiplexer that decides if PA0, PB0, ... or PG0 is connected to the EXTI0 signal:

STM32F103 ExtI0 schematic

That means that you cannot connect both PA0 and PB0 to EXTI0. In fact, there are four specific bits in the alternate function input/output register (AFIO) which let you choose which pin is connected to the EXTI0 signal. Here, these bits are located in the control register AFIO_EXTICR1. See the AFIO register map in the same document for further information.

Now I don't know which setup you are using, but as I recall, I had separate functions for different interrupt request routines (for EXTI0, EXTI1 and so on).