Today we successfully tested direct GPIO output control on a Raspberry Pi 4B using C# and .NET 8. Here's a quick recap of the progress:

1. GPIO Setup

• Connected a GPIO extension board to the Pi for easier breadboard access.

• Wired GPIO17 to an LED through a 1kΩ current-limiting resistor.

• Verified voltage with a multimeter before connecting the load.

2. Power Supply

• Initially used a SANMIM switching supply that delivered 4.9V.

• Swapped it out for a different supply delivering 5.04V to ensure the Pi was properly powered.

3. C# Code

• Created a minimal console application in Visual Studio targeting .NET 8.

• Used the System.Device.Gpio library to control GPIO17.

• Wrote code to drive the pin high for 10 seconds, then set it low.

• Observed GPIO17 output go to 3.3V, and the LED lit up brightly as expected.

4. Outcome

• GPIO test was a success using C# only, no Python required.

• This lays the foundation for moving forward with the MCP23017 I/O expander in future phases.
  

Code

using System;
using System.Device.Gpio;
using System.Threading;

class Program {
    static void Main() {
        int pin = 17; // GPIO17
        using var controller = new GpioController();

        controller.OpenPin(pin, PinMode.Output);
        Console.WriteLine("Setting GPIO17 HIGH (3.3V)");
        controller.Write(pin, PinValue.High);

        Thread.Sleep(10000); // Hold for 10 seconds

        Console.WriteLine("Turning GPIO17 LOW (0V)");
        controller.Write(pin, PinValue.Low);

        controller.ClosePin(pin);
        Console.WriteLine("Done.");
    }
}