WS2812-2020 Control#

The WS2812-2020 is a compact RGB LED that can be precisely controlled using the Touch Dot S3 board. This section provides technical guidance for driving WS2812 LEDs and generating custom lighting patterns with MicroPython, C++, and ESP-IDF.

On the Touch Dot S3, a dedicated GPIO pin (GPIO45) is directly connected to the WS2812 LED, allowing for straightforward hardware interfacing and reliable signal timing.

Table 12 Pin Mapping for WS2812#
PIN	GPIO ESP32-S3
DIN	45

rgb led — Fig. 21 WS2812-2020 LED Strip#

Note

The neopixel library is compatible with WS2812 and WS2812B LED strips. The WS2812-2020 is a variant of the WS2812B, so it is fully compatible with the neopixel library.

Code Example#

Below is an example that demonstrates how to control WS2812-2020 LED strips using the Touch Dot S3 board

from machine import Pin
from neopixel import NeoPixel
np = NeoPixel(Pin(45), 1)
np[0] = (255, 128, 0) # set to red, full brightness

np.write()

#include <Adafruit_NeoPixel.h>

#define PIN        45      // Cambia si GPIO45 no funciona
#define NUM_LEDS   1       // Número de LEDs en tu tira
Adafruit_NeoPixel strip(NUM_LEDS, PIN, NEO_GRB + NEO_KHZ800);

void setup() {
strip.begin();
strip.show(); // Apaga todos los LEDs al inicio
}

void loop() {
// Ciclo de colores
strip.setPixelColor(0, strip.Color(255, 0, 0));   // Rojo
strip.show();
delay(1000);

strip.setPixelColor(0, strip.Color(0, 255, 0));   // Verde
strip.show();
delay(1000);

strip.setPixelColor(0, strip.Color(0, 0, 255));   // Azul
strip.show();
delay(1000);

}

/*
* SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Unlicense OR CC0-1.0
*/
#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_log.h"
#include "driver/rmt_tx.h"
#include "led_strip_encoder.h"

#define RMT_LED_STRIP_RESOLUTION_HZ 10000000 // 10MHz resolution, 1 tick = 0.1us (led strip needs a high resolution)
#define RMT_LED_STRIP_GPIO_NUM      45

#define EXAMPLE_LED_NUMBERS         24
#define EXAMPLE_CHASE_SPEED_MS      10

static const char *TAG = "example";

static uint8_t led_strip_pixels[EXAMPLE_LED_NUMBERS * 3];

/**
* @brief Simple helper function, converting HSV color space to RGB color space
*
* Wiki: https://en.wikipedia.org/wiki/HSL_and_HSV
*
*/
void led_strip_hsv2rgb(uint32_t h, uint32_t s, uint32_t v, uint32_t *r, uint32_t *g, uint32_t *b)
{
   h %= 360; // h -> [0,360]
   uint32_t rgb_max = v * 2.55f;
   uint32_t rgb_min = rgb_max * (100 - s) / 100.0f;

   uint32_t i = h / 60;
   uint32_t diff = h % 60;

   // RGB adjustment amount by hue
   uint32_t rgb_adj = (rgb_max - rgb_min) * diff / 60;

   switch (i) {
   case 0:
      *r = rgb_max;
      *g = rgb_min + rgb_adj;
      *b = rgb_min;
      break;
   case 1:
      *r = rgb_max - rgb_adj;
      *g = rgb_max;
      *b = rgb_min;
      break;
   case 2:
      *r = rgb_min;
      *g = rgb_max;
      *b = rgb_min + rgb_adj;
      break;
   case 3:
      *r = rgb_min;
      *g = rgb_max - rgb_adj;
      *b = rgb_max;
      break;
   case 4:
      *r = rgb_min + rgb_adj;
      *g = rgb_min;
      *b = rgb_max;
      break;
   default:
      *r = rgb_max;
      *g = rgb_min;
      *b = rgb_max - rgb_adj;
      break;
   }
}

void app_main(void)
{
   uint32_t red = 0;
   uint32_t green = 0;
   uint32_t blue = 0;
   uint16_t hue = 0;
   uint16_t start_rgb = 0;

   ESP_LOGI(TAG, "Create RMT TX channel");
   rmt_channel_handle_t led_chan = NULL;
   rmt_tx_channel_config_t tx_chan_config = {
      .clk_src = RMT_CLK_SRC_DEFAULT, // select source clock
      .gpio_num = RMT_LED_STRIP_GPIO_NUM,
      .mem_block_symbols = 64, // increase the block size can make the LED less flickering
      .resolution_hz = RMT_LED_STRIP_RESOLUTION_HZ,
      .trans_queue_depth = 4, // set the number of transactions that can be pending in the background
   };
   ESP_ERROR_CHECK(rmt_new_tx_channel(&tx_chan_config, &led_chan));

   ESP_LOGI(TAG, "Install led strip encoder");
   rmt_encoder_handle_t led_encoder = NULL;
   led_strip_encoder_config_t encoder_config = {
      .resolution = RMT_LED_STRIP_RESOLUTION_HZ,
   };
   ESP_ERROR_CHECK(rmt_new_led_strip_encoder(&encoder_config, &led_encoder));

   ESP_LOGI(TAG, "Enable RMT TX channel");
   ESP_ERROR_CHECK(rmt_enable(led_chan));

   ESP_LOGI(TAG, "Start LED rainbow chase");
   rmt_transmit_config_t tx_config = {
      .loop_count = 0, // no transfer loop
   };
   while (1) {
      for (int i = 0; i < 3; i++) {
            for (int j = i; j < EXAMPLE_LED_NUMBERS; j += 3) {
               // Build RGB pixels
               hue = j * 360 / EXAMPLE_LED_NUMBERS + start_rgb;
               led_strip_hsv2rgb(hue, 100, 100, &red, &green, &blue);
               led_strip_pixels[j * 3 + 0] = green;
               led_strip_pixels[j * 3 + 1] = blue;
               led_strip_pixels[j * 3 + 2] = red;
            }
            // Flush RGB values to LEDs
            ESP_ERROR_CHECK(rmt_transmit(led_chan, led_encoder, led_strip_pixels, sizeof(led_strip_pixels), &tx_config));
            ESP_ERROR_CHECK(rmt_tx_wait_all_done(led_chan, portMAX_DELAY));
            vTaskDelay(pdMS_TO_TICKS(EXAMPLE_CHASE_SPEED_MS));
            memset(led_strip_pixels, 0, sizeof(led_strip_pixels));
            ESP_ERROR_CHECK(rmt_transmit(led_chan, led_encoder, led_strip_pixels, sizeof(led_strip_pixels), &tx_config));
            ESP_ERROR_CHECK(rmt_tx_wait_all_done(led_chan, portMAX_DELAY));
            vTaskDelay(pdMS_TO_TICKS(EXAMPLE_CHASE_SPEED_MS));
      }
      start_rgb += 60;
   }
}

Tip

for more information on the NeoPixel library, refer to the NeoPixel Library Documentation.

WS2812-2020 Control

Contents

WS2812-2020 Control#

Code Example#