Atomic PWM Base Arduino Tutorial

1. Preparation

• Environment Configuration: Refer to the Arduino IDE Quick Start Tutorial to install the IDE, add the board manager entries for your board, and install any required drivers and libraries.

• Required driver libraries:

  • M5Unified
  • M5GFX

• Hardware used:

  • AtomS3
  • Atomic PWM Base

2. Example

• In this tutorial the main controller is the AtomS3 paired with the Atomic PWM Base. The PWM output pin is G5 (SIGNAL).

#include "M5Unified.h"

#define SIGNAL 5 // PWM signal output pin

int freq        = 10000; // 10kHz
int resolution  = 10;    // Duty cycle resolution in bits (10-bit = 0 to 1023)

void setup() {
    M5.begin();

    M5.Display.setTextColor(GREEN);
    M5.Display.setTextDatum(middle_center);
    M5.Display.setFont(&fonts::Orbitron_Light_24);
    M5.Display.drawString("PWM", M5.Display.width() / 2, M5.Display.height() / 2);

    ledcAttach(SIGNAL, freq, resolution);// Bind the pin, frequency, and resolution
}

void loop() {
    for (int i = 0; i < 500; i++) {
        ledcWrite(SIGNAL, i);// Update the PWM duty cycle
        delay(2);
    }

    for (int i = 500; i > 0; i--) {
        ledcWrite(SIGNAL, i);
        delay(2);
    }
}

3. Compile and Upload

• 1. To enter download mode on AtomS3: press and hold the reset button for about 2 seconds until the internal green LED lights, then release — the device will enter download mode and is ready for flashing. The green LED turns off after the button is released, confirming that the device is in download mode.

• 2. Select the device port, then click the compile & upload button in the Arduino IDE (top-left). Wait for the sketch to finish compiling and uploading to the device.

4. PWM output to control LED strip brightness

• After power-up the device will start outputting the PWM signal. The LED strip will gradually brighten, then dim, and repeat the cycle.