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Built-in project · ESP32-C6-DevKitC-1

ESP32-C6 fade

Breathes an LED on GPIO 10 with analogWrite, so the waveform comes out of the LEDC hardware and the core sleeps between steps. The whole build, an ESP32-C6 and 2 more parts, runs here in your browser on the firmware below; open it in the editor to change the wiring or the code and run it again.

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ESP32-C6 fade · ESP32-C6-DevKitC-1live0.000 s 0.00x
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The circuit itself, running here on the simulator. Press what can be pressed; click anything else to open it in the editor.

The code

The firmware exactly as the editor opens it. Change a line there and press Run: it compiles in the browser.

sketch.ino · ESP32-C6-DevKitC-1
// Fade: a breathing LED on hardware PWM.
//
// LEDC, the chip's LED PWM controller, makes the waveform; the sketch only
// changes a number thirty-three times a second and sleeps in between. The core
// is parked in `wfi` for almost all of the two seconds a breath takes, and the
// edges still land where they should, because the PWM is in the hardware and
// not in the loop.
//
// analogWrite(pin, 0..255) is all this needs. Any GPIO will do: LEDC reaches
// the pins through the GPIO matrix, so there is no fixed set of `~` pins on
// this board.
//
// Wire an LED and a 220 R resistor from GPIO 10 to ground.

const uint8_t LED = 10;
const int STEPS = 64;
const unsigned long STEP_MS = 30;  // a whole breath takes about two seconds

// One cycle of (1 - cos)/2 scaled to 0..255. A linear ramp looks wrong: the
// eye is roughly logarithmic, so an even climb in duty is an uneven climb in
// brightness, and this is the shape that reads as breathing.
const uint8_t breath[STEPS] = {
    0,   1,   2,   6,  10,  16,  22,  29,
   38,  47,  57,  68,  79,  91, 103, 116,
  128, 140, 153, 165, 177, 188, 199, 209,
  218, 226, 234, 240, 246, 250, 253, 255,
  255, 255, 253, 250, 246, 240, 234, 226,
  218, 209, 199, 188, 177, 165, 153, 140,
  128, 116, 103,  91,  79,  68,  57,  47,
   38,  29,  22,  16,  10,   6,   2,   1,
};

void setup() {
  // Nothing to do: the first analogWrite attaches the pin to a free channel.
}

void loop() {
  for (int step = 0; step < STEPS; step++) {
    analogWrite(LED, breath[step]);
    delay(STEP_MS);
  }
}

Parts list

4 parts, plus the jumper wires. Every one is in the editor's parts bin.

How it is wired

3 connections, pin by pin, read from the circuit itself. Each line is one set of pins joined together, by a jumper wire or a breadboard strip.

  • ESP32-C6-DevKitC-1 pin 10; Resistor, 220 Ω pin 1
  • Ground: ESP32-C6-DevKitC-1 pin GND; LED, yellow pin C
  • Resistor, 220 Ω pin 2; LED, yellow pin A

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