I'm writing in C++ using WiringPi to integrate with GPIO but it doesn't seem to work during runtime.

Below I have a simple example of an output wired to an input expecting the input to read HIGH, but it is not outputting anything. I've tried running in the terminal gpio -g mode 24 out and neither the Mode or V voltage values change when running gpio readall.

pinMode(24, OUTPUT);
pinMode(25, INPUT);

digitalWrite(24, HIGH);
RCLCPP_INFO(get_logger(), "25: %d", digitalRead(25)); // ROS 2 cout equivalent 

I've also tried configuring input reading from the 3.3V output and still reading 0. I used a voltmeter to confirm it wasn't a hardware issue.

Why is it not working? Any insight on how to fix/debug this?


  • Which OS??? Perhaps you didn't read enough?
    – Seamus
    Nov 27, 2023 at 23:14
  • Wiring Pi will not work on a Raspberry Pi 5. It's a wonder it still works anywhere, it's been unsupported since 2019. Change to any other GPIO library, like gpiod.
    – Dougie
    Nov 27, 2023 at 23:15
  • OS: Ubuntu 22.04 Model: Raspberry Pi 4
    – Yato
    Nov 28, 2023 at 16:36
  • I actually got the gpio terminal commands working and it reflected correctly in the gpio readall. Using the library in a C++ file is not working still.
    – Yato
    Nov 28, 2023 at 19:45
  • I was following Setup and API and nothing on the second link worked for me.
    – Yato
    Nov 28, 2023 at 19:47


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