A20 GPIO Interruption

OpenglMan · March 10, 2018

Hello,

I need to use an IRQ interruption with a button. I mean, I push a button, and then a code is executed.

Some information: The PIN is PH19, EINT19. and the board A20 SOM. Armbian SO, kernel 4.13

Firstly i configure the digital pin and IRQ from user space:

echo 243 > /sys/class/gpio/export

echo "in" > /sys/class/gpio/gpio243/direction

echo "falling" > /sys/class/gpio/gpio243/edge

Now, when I push the button, I can monitoring the IRQ and the counter related to

cat /proc/interrupts

But now, how can I run a program when the interruption event happens ?

I have seen this useful link

http://linux-sunxi.org/External_interrupts

How can i use it? I think there is very few information about this issue.

I executed a bash script with while true , and polling the digital pin, but the disadvantage is that it consumes a lot of cpu.

I hope you can help me. Thank you very much in advance

Regards

martinayotte · March 10, 2018

It shoud not take a lot of cpu using poll() function with proper arguments.

Take a look at this example :

http://developer.ridgerun.com/wiki/index.php?title=Gpio-int-test.c

http://developer.ridgerun.com/wiki/index.php/How_to_use_GPIO_signals

OpenglMan · March 11, 2018

Thank you martinayotte for your answer.

However i have found an alternative solution in PHP language that works pretty well. It barely consumes CPU. The code is very simple. Anyway I will try the code in c language that you indicated in your previous post. I imagine that the internal functioning will be similar in both solutions.

If anyone is interested, check the following link:

https://github.com/PacktPublishing/GNU-Linux-Rapid-Embedded-Programming/blob/master/Chapter06/gpio-poll.php

Regards