esp_stripper 🌈💃

Put on a show with this LED strip driver!

Designed for use with ESP32 applications built on the ESP-IDF framework.

The reference implementation for driving LED strips using the RMT peripheral of the ESP32 is broken (official ESP-IDF example here). Or at least it appears to be when used alongside WiFi, Bluetooth, or other processing-intensive applications (frequent flash reads/writes, etc.). In these scenarios the RMT driver, is prone to introduce artifacts and glitches in the data transmission stream, resulting in flashing and random colors shown on the LED strip.

esp_stripper is a lean, performant, C-based port of the excellent FastLED driver (Github: https://github.com/FastLED/FastLED/tree/master/src/platforms/esp/32). This implementation is not vulnerable to the flickers and flashes of the basic RMT driver implementation.

Installation

esp_stripper is meant to be used as a component as described in the ESP-IDF Build System documentation. Simply clone this repo into the components directory of your application:

cd <your-esp32-app>/components
git clone git@github.com:Vivero/esp_stripper.git

Alternatively, copy the esp_stripper.h and esp_stripper.c files into your project and include/link them as you see fit. Or add this repo as a submodule in your own app repo.

Usage

API usage and implementation details are described in the header file esp_stripper.h.

Example

Here's a minimal example to get an LED strip lit:

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_stripper.h"
#include "driver/gpio.h"
#include <stdio.h>

static void StripperTask(void* pvParameters);

void app_main(void)
{
    printf("Hello esp_stripper!\n");

    // Initialize esp_stripper on Core 1 to minimize interference with WiFi
    xTaskCreatePinnedToCore(
        StripperTask,
        "Stripper",
        2048 /* usStackDepth */,
        NULL, /* pvParameters */
        10 /* uxPriority */,
        NULL, /* flags */
        1 /* xCoreID */);
}

static void StripperTask(void* pvParameters)
{
    esp_stripper_init(); // Call me once, and then never again

    const uint8_t stripper_index = 0; // Pick any number between 0-7
    esp_stripper_ctrl_config_t cfg =
    {
        .ChipType = ESP_STRIPPER_CHIP_WS2812B,
        .uGpioNum = GPIO_NUM_27,
        .uNumPixels = 99, // I got 99 pixels but a snitch ain't one
    };
    esp_stripper_config_controller(stripper_index, &cfg);
    esp_stripper_clear_pixels(stripper_index);

    // Pack color data into 4x 8-bit channels (Red, Green, Blue, Alpha):
    // 0x00000000
    //    ^ ^ ^ ^
    //    A B G R
    //
    // Don't worry about channel order, `esp_stripper` will figure it out
    // based on the above `cfg.ChipType`

    // Light up the first 5 pixels on the strip: red, green, blue, yellow, white
    uint32_t my_colors[6] = {0x000000FF, 0x0000FF00, 0x00FF0000, 0x0000FFFF, 0x00FFFFFF, 0x00000000};
    esp_stripper_load_pixels(stripper_index, my_colors, 5, 0);

    uint8_t red = 0;
    for (;;)
    {
        // Cycle the 6th pixel with shades of red
        red++;
        my_colors[5] = (uint32_t)red;
        esp_stripper_load_pixels(stripper_index, &my_colors[5], 1, 5);

        // Draw me like one of your French girls, every 1 second
        esp_stripper_display(); // This is a blocking call
        vTaskDelay((1000 /* msec */) / portTICK_PERIOD_MS);
    }

    // Destroy me
    esp_stripper_deinit();
    vTaskDelete(NULL);
}