Problem Handling GPIOs

Dear All;

I do have a problem while dealing with GPIOs , I have set one of the GPIO pins mode to input , GPIO 141 specifically.

My application is written in C++ and run on the ubuntu version provided with the UDOO quad board.

the problem is , at the beginning of the code running , I can read the value of that pin correctly , after a while of the code running , the value of the pin is not changed

the input wire is 3.3v , but the value file of the GPIO 141 is not changed and is set to 0 ..

Where would be the problem ... also if there is a full c++ example of how to deal with GPIO effectively and handle the connectivity with the Arduino side too .. that would be great.

thanks ..

 

Hi there,
what is connected to GPIO 141 ? Who or what drive this pin? If it's an external device, are grounds connected?

 

hello

the pin is drived from external source and yes they have a common ground.

 

Could you try to use it with another GPIO to check if you get a different behaviour?

 

Just one possibility, but if you're not currently using the Arduino-side SAM3X CPU for anything, try forcing it into RESET state, to ensure a sketch loaded there isn't interfering with this shared GPIO pin. If you don't want to fiddle with the jumper, "echo 0 >/sys/class/gpio/gpio0/value" will hold the SAM3X in RESET.