PwmLed

🌶️ - Pulse Width Modulation (PWM) and changing the light of a LED

Shows how to use the System.Device.Pwm API to use Pulse Width Modulation pins.

We will use the embedded LED present on the board for this case. You can also use an external LED with the 100-ohm resistor. You can follow the following schema.

And if you want to know more about PWM, how this works, you can read the All what you've always wanted to know about PWM content!

Running the sample

Ensure you have all the software requirements.

To build the sample, follow the section here. And to run it, here.

The sample is located here. The code is very straightforward with the explanations:

using System.Device.Pwm;
using System.Diagnostics;
using System.Threading;
using nanoFramework.Hardware.Esp32;

Debug.WriteLine("Hello from nanoFramework!");

// Pin 2 is the integrated LED in the ESP32, if you are using another board, change the pin number
int pinLed = 2;

// If you have an ESP32, you should setup the pin first to be used with PWM:
Configuration.SetPinFunction(pinLed, DeviceFunction.PWM1);

// Then you can create the PWM Channel from the pin:
PwmChannel pwmPin = PwmChannel.CreateFromPin(pinLed, 40000, 0);
// Note: even if possible, it is not recommended to adjust the frequency once created.

// Start the PWM
pwmPin.Start();

// Now, we will loop to increase and decrease the duty cycle
while (true)
{
    // We will increase the duty cycle by 1 percent every 20 milliseconds
    for (int i = 0; i <= 100; i++)
    {
        pwmPin.DutyCycle = (double)i / 100;
        Thread.Sleep(20);
    }

    // We will decrease the duty cycle by 1 percent every 20 milliseconds
    for (int i = 100; i >= 0; i--)
    {
        pwmPin.DutyCycle = (double)i / 100;
        Thread.Sleep(20);
    }
}

Thread.Sleep(Timeout.Infinite);

And as a result, you will see:

If you want to debug, follow the instructions explained in the led sample.