esp32WS2811

Arduino Library for ESP32 to drive WS2811/WS2812 RGB leds using the RMT peripheral. The lib is lean and only drives the leds.

Hardware

As the ESP32 uses 3.3V levels and the WS2811 uses 5V, we need a level shifting device. I'm successfully using a TXS-0102 voltage-level translator. I've tested up to 50 leds and wire lengths to the first LED up to 2 meters.

Example circuit:

                                  3.3V                                  5V
                                    |                                    |
                                    |                                    |
      +--------------+              |         +---------------+          |
      |          Vin +--------------+---------+ Vcca     Vccb +----------+
      |              |                        |               |          |
      |      GPIO 23 +--------------------+-->+ OE       GND  +---+--||--+----- Vdd WS2811
      |     ESP32    |                    |   |     TXS0102   |   |  0.1µF
      |      GPIO 18 +----------------------->+ A1         B1 +---------------- DATA WS2811
      |              |                    |   |               |   |
      |     GND      |                    |   | A2         B2 |   +------------ GND WS2811
      +------+-------+                    |   +---------------+   |
             |                            |                       |
             |                            +--/\/\/\---+-------- --+
             |                                10k     |
             +----------------------------------------+
                                                      |
                                                     ---

The pulldown resistor on OE (output enable) prevents the output to float during startup. Unused pins are left unconnected as they have internal 10k pullups.

Firmware

Include the header file and define your LED string:

#include <esp32WS2811.h>

// first argument is the data pin, the second argument is the number of LEDs
WS2811 yourLedString(18, 50);

Start the LED string:

void setup() {
  // include your other code

  yourLedString.begin();
}

Change LED colours:

Colour colour = yourLedString.getPixel(size_t index);  // gives you the Colour of the led on index.
yourLedString.setPixel(size_t index, uint32_t red, uint32_t green, uint32_t blue);
yourLedString.show();  // this actually makes the LEDs light up

A number of helpers methods are available:

yourLedString.clearAll();  // turns off all LEDs
yourLedString.setAll(Colour colour);  // // gives all LEDs the specified colour
yourLedString.setAll(uint32_t red, uint32_t green, uint32_t blue);  // gives all LEDs the specified colour

Keep in mind that all these methods require to call show() afterwards.

Effects

Starting and stopping an effect is done by:

void startEffect(WS2811Effect* effect);
void stopEffect();

You don't have to stop a running effect before starting a new one. The effect stops immediately and does not wait for it's routine to complete.

Sample application

You can find a full working application in this repo: ledController

Credits

• The RMT driver for WS2811/WS2812 comes from @nkolban https://github.com/nkolban/esp32-snippets.
• Aurora effect source from https://github.com/Mazn1191/Arduino-Borealis