SDMMC card detect interrupt and lcd touch interrupt on same EXTI line

2 replies
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Hello,

in STM32F746 DISCO.

Microsd detect pin is : PC13

LCD touch interrupt is : PI13

how to make use of both interrupts in the application ?

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Danish1Best answer

Lead III

The short answer is "you can't". At least not using EXTI interrupt.

So how might you achieve the desired result instead?

PC13 happens to be RTC_TAMP1, so you could enable and use the corresponding RTC interrupt, leaving EXTI13 wired to PI13.

Or, since (in my experience) it takes quite a long time to mount a microSD card once it is inserted, maybe the detection of its insertion could be delayed by (say) up to 100 ms. In that case all you need do is poll PC13 in software every 100 ms. I suspect some real-time operating-systems make this fairly easy. But you could also do this in response to a timer interrupt.

Hope this helps,

Danish

Danish1Best answer

Lead III

The short answer is "you can't". At least not using EXTI interrupt.

So how might you achieve the desired result instead?

PC13 happens to be RTC_TAMP1, so you could enable and use the corresponding RTC interrupt, leaving EXTI13 wired to PI13.

Or, since (in my experience) it takes quite a long time to mount a microSD card once it is inserted, maybe the detection of its insertion could be delayed by (say) up to 100 ms. In that case all you need do is poll PC13 in software every 100 ms. I suspect some real-time operating-systems make this fairly easy. But you could also do this in response to a timer interrupt.

Hope this helps,

Danish

n.serinaAuthor

Associate III

Hello Danish,

Great insights . Thanks for the clarification .

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