[fpc-pascal] RaspberryPi GPIO access from multiple applications using /dev/gpiomem?

Bo Berglund bo.berglund at gmail.com
Mon Mar 22 11:25:04 CET 2021

I have a control application that uses GPIO pins to switch ON/OFF power feed to
a data collection system and to start it using a trigger pulse.

Now I am trying to remotely debug this system and I have trouble knowing in
which power state it is actually in...

I am using the "driver" PiGpio.pas by Gabor Szollosi from 2013 and it works well
for everything I have tested it with (I have added a switch to define the 2
generations of RPi).

To debug my application I need to see the state of the control lines when the
system is stepped through its functions but I am unable to travel to the
I do have access to the RPi3 using SSH via PuTTY and the desktop via VNC,

Can two different applications access the (same) GPIO pins without permission

In my case I only need read access to the active pins so I can display the state
in a monitoring application I can watch via VNC. Checking a few times per second
is enough, I think.

But I don't know if the GPIO pins are protected when they are in use by another

Bo Berglund
Developer in Sweden

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