TasmotaLED Library Documentation

Executive Summary

TasmotaLED is a lightweight, high-performance library for controlling addressable LED strips on ESP32 microcontrollers. It serves as a streamlined replacement for the NeoPixelBus library, focusing on efficient pixel pushing with minimal memory overhead while supporting multiple hardware acceleration methods (RMT, SPI, I2S).

Key Features:

Hardware-accelerated LED control via RMT (preferred), SPI, or I2S
Support for WS2812 and SK6812 LED strips
3-byte (RGB) and 4-byte (RGBW) pixel formats
Flexible pixel ordering (GRB, RGB, RBG, BRG, BGR, GBR)
Zero-copy buffer management for optimal performance
ESP32 platform exclusive (ESP8266 not supported)

Version: 1.0
Author: Stephan Hadinger
License: GNU General Public License v3.0
Copyright: 2024

Architecture Overview
Class Hierarchy
LED Type Encoding System
Hardware Acceleration
API Reference
Configuration Guide
Performance Characteristics
Usage Examples
Integration with Tasmota
Troubleshooting

Architecture Overview

Design Philosophy

TasmotaLED is designed with the following principles:

Minimal Memory Footprint: Uses only two buffers (work and show) with no buffer swapping overhead
Hardware Acceleration First: Leverages ESP32's RMT, SPI, or I2S peripherals for precise timing
Zero-Copy Operations: Direct buffer manipulation without intermediate copies
NeoPixelBus Compatibility: Similar API for easy migration from NeoPixelBus
Compile-Time Optimization: Hardware support can be selectively enabled/disabled

System Architecture

┌─────────────────────────────────────────────────────────────┐
│                    Application Layer                        │
│              (Tasmota Light Driver)                         │
└────────────────────┬────────────────────────────────────────┘
                     │
                     ▼
┌─────────────────────────────────────────────────────────────┐
│                   TasmotaLED Class                          │
│  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐       │
│  │  _buf_work   │  │  _buf_show   │  │ Pixel Format │       │
│  │  (editable)  │─▶│  (internal)  │  │  Conversion  │       │
│  └──────────────┘  └──────────────┘  └──────────────┘       │
└────────────────────┬────────────────────────────────────────┘
                     │
                     ▼
┌─────────────────────────────────────────────────────────────┐
│              TasmotaLEDPusher (Abstract)                    │
└────────────────────┬────────────────────────────────────────┘
                     │
        ┌────────────┼────────────┐
        ▼            ▼            ▼
┌──────────────┐ ┌──────────┐ ┌──────────┐
│ RMT Pusher   │ │   SPI    │ │   I2S    │
│  (Primary)   │ │  Pusher  │ │  Pusher  │
└──────┬───────┘ └────┬─────┘ └────┬─────┘
       │              │            │
       ▼              ▼            ▼
┌─────────────────────────────────────────┐
│         ESP32 Hardware Peripherals      │
│    (RMT / SPI / I2S Controllers)        │
└─────────────────────────────────────────┘

Memory Management

TasmotaLED uses a dual-buffer system:

Work Buffer (_buf_work):
- Directly accessible by application
- Stores pixels in WRGB or RGB format (0xWWRRGGBB or 0xRRGGBB)
- Can be modified at any time
- Size: pixel_count × pixel_size bytes
Show Buffer (_buf_show):
- Internal buffer for hardware transmission
- Stores pixels in LED strip format (e.g., GRB, GRBW)
- Populated during Show() call with format conversion
- Size: pixel_count × pixel_size bytes

Memory Allocation Example:

512 RGB pixels: 2 × 512 × 3 = 3,072 bytes (~3 KB)
512 RGBW pixels: 2 × 512 × 4 = 4,096 bytes (~4 KB)

Class Hierarchy

Class Diagram

┌─────────────────────────────────────────────────────────────┐
│                      TasmotaLED                             │
├─────────────────────────────────────────────────────────────┤
│ - _type: uint16_t                                           │
│ - _pixel_order: uint8_t                                     │
│ - _w_before: bool                                           │
│ - _pixel_reverse: bool                                      │
│ - _timing: uint8_t                                          │
│ - _started: bool                                            │
│ - _dirty: bool                                              │
│ - _raw_format: bool                                         │
│ - _pixel_count: uint16_t                                    │
│ - _pixel_size: uint8_t                                      │
│ - _buf_work: uint8_t*                                       │
│ - _buf_show: uint8_t*                                       │
│ - _pixel_matrix: const uint8_t(*)[3]                        │
│ - _pusher: TasmotaLEDPusher*                                │
├─────────────────────────────────────────────────────────────┤
│ + TasmotaLED(type, num_leds)                                │
│ + ~TasmotaLED()                                             │
│ + Begin(): bool                                             │
│ + Show(): void                                              │
│ + SetPixelColor(index, wrgb): void                          │
│ + GetPixelColor(index): uint32_t                            │
│ + ClearTo(rgbw, first, last): void                          │
│ + SetPixelCount(num_leds): void                             │
│ + SetPixelSubType(type): void                               │
│ + SetPusher(pusher): void                                   │
│ + CanShow(): bool                                           │
│ + Pixels(): uint8_t*                                        │
│ + PixelCount(): uint16_t                                    │
│ + PixelSize(): uint8_t                                      │
│ + GetType(): uint8_t                                        │
│ + IsDirty(): bool                                           │
│ + Dirty(): void                                             │
│ + SetPixelReverse(bool): void                               │
│ + SetRawFormat(raw): void                                   │
└─────────────────────────────────────────────────────────────┘
                            │
                            │ uses
                            ▼
┌─────────────────────────────────────────────────────────────┐
│              TasmotaLEDPusher (Abstract)                    │
├─────────────────────────────────────────────────────────────┤
│ # _initialized: bool                                        │
│ # _err: esp_err_t                                           │
│ # _pixel_count: uint16_t                                    │
│ # _pixel_size: uint16_t                                     │
│ # _led_timing: const TasmotaLED_Timing*                     │
├─────────────────────────────────────────────────────────────┤
│ + Begin(pixel_count, pixel_size, timing): bool              │
│ + Push(buf): bool = 0                                       │
│ + CanShow(): bool = 0                                       │
│ + SetPixelCount(pixel_count): bool = 0                      │
│ + Initialized(): bool                                       │
│ + Error(): esp_err_t                                        │
│ + static ResolveHardware(hw): uint32_t                      │
│ + static Create(hw, gpio): TasmotaLEDPusher*                │
└─────────────────────────────────────────────────────────────┘
                            △
                            │
          ┌─────────────────┼─────────────────┐
          │                 │                 │
┌─────────┴──────────┐ ┌────┴─────────┐ ┌─────┴──────────┐
│ TasmotaLEDPusherRMT│ │TasmotaLED    │ │ TasmotaLED     │
│                    │ │PusherSPI     │ │PusherI2S       │
├────────────────────┤ ├──────────────┤ ├────────────────┤
│ - _pin: int8_t     │ │- _pin: int8_t│ │(Future)        │
│ - _channel: handle │ │- _spi_strip  │ │                │
│ - _led_encoder     │ │- _with_dma   │ │                │
│ - _tx_config       │ │              │ │                │
├────────────────────┤ ├──────────────┤ ├────────────────┤
│ + Push(): bool     │ │+ Push(): bool│ │                │
│ + CanShow(): bool  │ │+ CanShow()   │ │                │
└────────────────────┘ └──────────────┘ └────────────────┘

LED Type Encoding System

Type Encoding Structure

The LED type is encoded in a 16-bit value with the following bit layout:

Bits 15-8: Timing Code (WS2812, SK6812, etc.)
Bit  7:    W Channel Position (0=after RGB, 1=before RGB)
Bits 6-4:  Pixel Order (GRB, RGB, RBG, BRG, BGR, GBR)
Bits 3-0:  Bytes per Pixel (3=RGB, 4=RGBW)

┌────────┬───┬───────┬──────────┐
│15    8 │ 7 │ 6   4 │ 3      0 │
├────────┼───┼───────┼──────────┤
│ Timing │ W │ Order │   Size   │
└────────┴───┴───────┴──────────┘

Pixel Size Encoding (Bits 0-3)

Value	Enum	Description	Bytes per Pixel
`0x0`	`TasmotaLed_1_Def`	Default (same as RGB)	3
`0x1`	`TasmotaLed_3_RGB`	RGB format	3
`0x2`	`TasmotaLed_4_WRGB`	RGBW format	4

Pixel Order Encoding (Bits 4-6)

Value	Enum	Description	Channel Order
`0b000`	`TasmotaLed_Def`	Default (GRB)	G, R, B
`0b001`	`TasmotaLed_GRB`	Green-Red-Blue	G, R, B
`0b010`	`TasmotaLed_RGB`	Red-Green-Blue	R, G, B
`0b011`	`TasmotaLed_RBG`	Red-Blue-Green	R, B, G
`0b100`	`TasmotaLed_BRG`	Blue-Red-Green	B, R, G
`0b101`	`TasmotaLed_BGR`	Blue-Green-Red	B, G, R
`0b110`	`TasmotaLed_GBR`	Green-Blue-Red	G, B, R

W Channel Position (Bit 7)

Value	Enum	Description	Format
`0`	`TasmotaLed_xxxW`	W after color	RGB + W
`1`	`TasmotaLed_Wxxx`	W before color	W + RGB

Timing Code (Bits 8-15)

Value	Enum	Description	T0H	T0L	T1H	T1L	Reset
`0`	`TasmotaLed_WS2812`	WS2812/WS2812B	400ns	850ns	800ns	450ns	80µs
`1`	`TasmotaLed_SK6812`	SK6812	300ns	900ns	600ns	600ns	80µs

Predefined LED Types

cpp

enum TasmotaLEDTypes : uint16_t {
  // WS2812 with GRB ordering (most common)
  ws2812_grb  = TasmotaLed_3_RGB | TasmotaLed_GRB | TasmotaLed_WS2812,
  // Value: 0x0011 (decimal 17)
  
  // SK6812 with GRBW ordering and W after RGB
  sk6812_grbw = TasmotaLed_4_WRGB | TasmotaLed_GRB | TasmotaLed_xxxW | TasmotaLed_SK6812,
  // Value: 0x0112 (decimal 274)
  
  // SK6812 with GRB ordering (no white channel)
  sk6812_grb  = TasmotaLed_3_RGB | TasmotaLed_GRB | TasmotaLed_SK6812,
  // Value: 0x0111 (decimal 273)
};

Type Encoding Examples

cpp

// WS2812 RGB strip with GRB ordering
uint16_t type1 = TasmotaLed_3_RGB | TasmotaLed_GRB | TasmotaLed_WS2812;
// Binary: 0000 0000 0001 0001 = 0x0011

// SK6812 RGBW strip with RGB ordering and W first
uint16_t type2 = TasmotaLed_4_WRGB | TasmotaLed_RGB | TasmotaLed_Wxxx | TasmotaLed_SK6812;
// Binary: 0000 0001 1010 0010 = 0x01A2

// WS2812 RGB strip with BGR ordering
uint16_t type3 = TasmotaLed_3_RGB | TasmotaLed_BGR | TasmotaLed_WS2812;
// Binary: 0000 0000 0101 0001 = 0x0051

Hardware Acceleration

Hardware Support Matrix

Hardware	ESP32	ESP32-S2	ESP32-S3	ESP32-C3	ESP32-C2	ESP32-C6
RMT	✅	✅	✅	✅	❌	✅
SPI	✅	✅	✅	✅	✅	✅
I2S	✅	✅	✅	❌	❌	❌

Hardware Selection

Hardware acceleration is selected using the TasmotaLEDHardware enum:

cpp

enum TasmotaLEDHardware : uint32_t {
  TasmotaLed_HW_Default = 0x000000,  // Auto-select best available
  TasmotaLed_RMT  = (1 << 0) << 16,  // 0x010000 - RMT peripheral
  TasmotaLed_SPI  = (1 << 1) << 16,  // 0x020000 - SPI peripheral
  TasmotaLed_I2S  = (1 << 2) << 16,  // 0x040000 - I2S peripheral
  TasmotaLed_HW_None = 0xFF << 16,   // 0xFF0000 - No hardware support
};

Hardware Resolution Priority

When TasmotaLed_HW_Default is specified, the library selects hardware in this order:

RMT (if available) - Preferred for precision and low CPU overhead
I2S (if available) - Good for large strips
SPI (if available) - Fallback option, works on all ESP32 variants

Compile-Time Configuration

Hardware support can be enabled/disabled at compile time:

cpp

// In your build configuration or before including TasmotaLED
#define TASMOTALED_HARDWARE_RMT 1  // Enable RMT (default: 1)
#define TASMOTALED_HARDWARE_I2S 0  // Enable I2S (default: 0)
#define TASMOTALED_HARDWARE_SPI 0  // Enable SPI (default: 0)

Note: If no hardware is explicitly enabled, SPI is automatically enabled as fallback.

RMT Implementation

Advantages:

Precise timing control (25ns resolution at 40MHz)
Low CPU overhead
Non-blocking operation with DMA
Supports up to 8 channels (ESP32) or 4 channels (ESP32-S2/S3/C3)

Technical Details:

Clock resolution: 40 MHz (25ns per tick)
Memory block: 192 symbols (768 bytes)
Transaction queue depth: 4
Encoder: Custom LED strip encoder with bit-level control

Timing Precision:

WS2812: T0H=400ns (16 ticks), T0L=850ns (34 ticks)
        T1H=800ns (32 ticks), T1L=450ns (18 ticks)
        Reset=80µs (3200 ticks)

SK6812: T0H=300ns (12 ticks), T0L=900ns (36 ticks)
        T1H=600ns (24 ticks), T1L=600ns (24 ticks)
        Reset=80µs (3200 ticks)

SPI Implementation

Advantages:

Available on all ESP32 variants
Works on ESP32-C2 (no RMT support)
Reliable fallback option

Technical Details:

Clock frequency: 2.5 MHz
Each LED bit encoded as 3 SPI bits
Bit encoding: 0 = 100, 1 = 110
DMA support: Optional (auto-selected)
Memory overhead: 3× pixel buffer size

Bit Encoding:

LED bit 0: SPI bits 100 (high for 400ns, low for 800ns at 2.5MHz)
LED bit 1: SPI bits 110 (high for 800ns, low for 400ns at 2.5MHz)

I2S Implementation

Status: Planned but not yet implemented

Advantages:

Very high throughput
Excellent for large LED installations
Parallel data transmission

API Reference

TasmotaLED Class

Constructor

cpp

TasmotaLED(uint16_t type, uint16_t num_leds)

Creates a new TasmotaLED instance.

Parameters:

type: LED type encoding (see LED Type Encoding section)
num_leds: Number of LEDs in the strip

Example:

cpp

// Create a 60-LED WS2812 strip with GRB ordering
TasmotaLED strip(ws2812_grb, 60);

// Create a 100-LED SK6812 RGBW strip
TasmotaLED strip(sk6812_grbw, 100);

Destructor

cpp

~TasmotaLED()

Cleans up resources, frees buffers, and deletes the pusher instance.

Initialization Methods

SetPusher()

cpp

void SetPusher(TasmotaLEDPusher *pusher)

Sets the hardware pusher implementation. Must be called before Begin().

Parameters:

pusher: Pointer to a TasmotaLEDPusher instance (RMT, SPI, or I2S)

Example:

cpp

TasmotaLED strip(ws2812_grb, 60);
TasmotaLEDPusher *pusher = TasmotaLEDPusher::Create(TasmotaLed_RMT, 5);
strip.SetPusher(pusher);

Begin()

cpp

bool Begin(void)

Initializes the hardware pusher and prepares the strip for operation.

Returns: true if initialization successful, false otherwise

Example:

cpp

if (strip.Begin()) {
  // Strip is ready to use
} else {
  // Initialization failed
}

Pixel Manipulation Methods

SetPixelColor()

cpp

void SetPixelColor(int32_t index, uint32_t wrgb)

Sets the color of a single pixel.

Parameters:

index: Pixel index (0-based, negative values count from end)
wrgb: Color value in 0xWWRRGGBB format (or 0xRRGGBB for RGB strips)

Example:

cpp

strip.SetPixelColor(0, 0xFF0000);      // Red
strip.SetPixelColor(1, 0x00FF00);      // Green
strip.SetPixelColor(2, 0x0000FF);      // Blue
strip.SetPixelColor(-1, 0xFFFFFF);     // Last pixel white
strip.SetPixelColor(10, 0x80FF8000);   // RGBW: W=0x80, R=0xFF, G=0x80, B=0x00

GetPixelColor()

cpp

uint32_t GetPixelColor(int32_t index)

Retrieves the color of a single pixel.

Parameters:

index: Pixel index (0-based, negative values count from end)

Returns: Color value in 0xWWRRGGBB or 0xRRGGBB format

Example:

cpp

uint32_t color = strip.GetPixelColor(5);
uint8_t red = (color >> 16) & 0xFF;
uint8_t green = (color >> 8) & 0xFF;
uint8_t blue = color & 0xFF;

ClearTo()

cpp

void ClearTo(uint32_t rgbw, int32_t first = 0, int32_t last = -1)

Sets a range of pixels to the same color.

Parameters:

rgbw: Color value in 0xWWRRGGBB or 0xRRGGBB format
first: First pixel index (default: 0)
last: Last pixel index (default: -1 = last pixel)

Example:

cpp

strip.ClearTo(0x000000);           // Clear entire strip to black
strip.ClearTo(0xFF0000, 0, 9);     // Set first 10 pixels to red
strip.ClearTo(0x00FF00, 10, 19);   // Set pixels 10-19 to green
strip.ClearTo(0x0000FF, -10, -1);  // Set last 10 pixels to blue

Show()

cpp

void Show(void)

Pushes the pixel buffer to the LED strip. Converts from WRGB/RGB format to the strip's native format and transmits via hardware.

Example:

cpp

strip.SetPixelColor(0, 0xFF0000);
strip.SetPixelColor(1, 0x00FF00);
strip.Show();  // Update the strip

CanShow()

cpp

bool CanShow(void) const

Checks if the strip is ready to accept a new Show() command.

Returns: true if ready, false if previous transmission still in progress

Example:

cpp

if (strip.CanShow()) {
  strip.Show();
}

Configuration Methods

SetPixelCount()

cpp

void SetPixelCount(uint16_t num_leds)

Changes the number of LEDs in the strip. Reallocates buffers if necessary.

Parameters:

num_leds: New number of LEDs

Example:

cpp

strip.SetPixelCount(100);  // Resize to 100 LEDs

SetPixelSubType()

cpp

void SetPixelSubType(uint8_t type)

Changes only the pixel ordering and size (lower 8 bits of type), keeping timing unchanged.

Parameters:

type: New subtype (bits 0-7 of type encoding)

Example:

cpp

// Change from GRB to RGB ordering
strip.SetPixelSubType(TasmotaLed_3_RGB | TasmotaLed_RGB);

SetRawFormat()

cpp

void SetRawFormat(bool raw_format)

Enables/disables raw format mode. When enabled, buffer is copied directly without format conversion.

Parameters:

raw_format: true for raw mode, false for automatic conversion

Example:

cpp

strip.SetRawFormat(true);  // Disable format conversion

Query Methods

PixelCount()

cpp

uint16_t PixelCount(void) const

Returns the number of LEDs in the strip.

PixelSize()

cpp

uint8_t PixelSize(void) const

Returns the number of bytes per pixel (3 for RGB, 4 for RGBW).

GetType()

cpp

uint8_t GetType(void) const

Returns the LED type encoding.

Pixels()

cpp

uint8_t * Pixels(void) const

Returns a pointer to the work buffer for direct manipulation.

Example:

cpp

uint8_t *buf = strip.Pixels();
// Direct buffer access (advanced usage)
buf[0] = 0xFF;  // Set first byte

IsDirty()

cpp

bool IsDirty(void) const

Returns the dirty flag (for NeoPixelBus compatibility, but not used internally).

Dirty()

cpp

void Dirty(void)

Sets the dirty flag to true.

TasmotaLEDPusher Class (Abstract)

Static Factory Methods

Create()

cpp

static TasmotaLEDPusher * Create(uint32_t hw, int8_t gpio)

Creates a pusher instance for the specified hardware type.

Parameters:

hw: Hardware type (TasmotaLed_RMT, TasmotaLed_SPI, TasmotaLed_I2S, or TasmotaLed_HW_Default)
gpio: GPIO pin number for LED data output

Returns: Pointer to pusher instance, or nullptr if creation failed

Example:

cpp

TasmotaLEDPusher *pusher = TasmotaLEDPusher::Create(TasmotaLed_RMT, 5);
if (pusher) {
  strip.SetPusher(pusher);
}

ResolveHardware()

cpp

static uint32_t ResolveHardware(uint32_t hw)

Resolves hardware type based on SOC capabilities.

Parameters:

hw: Requested hardware type

Returns: Resolved hardware type (removes unsupported flags)

Instance Methods

Begin()

cpp

virtual bool Begin(uint16_t pixel_count, uint16_t pixel_size, 
                   const TasmotaLED_Timing * led_timing)

Initializes the hardware pusher.

Parameters:

pixel_count: Number of LEDs
pixel_size: Bytes per pixel (3 or 4)
led_timing: Pointer to timing structure

Returns: true if successful

Push()

cpp

virtual bool Push(uint8_t *buf) = 0

Pushes pixel data to the LED strip (pure virtual).

Parameters:

buf: Pointer to pixel buffer in strip format

Returns: true if successful

CanShow()

cpp

virtual bool CanShow(void) = 0

Checks if hardware is ready for next transmission (pure virtual).

Returns: true if ready

SetPixelCount()

cpp

virtual bool SetPixelCount(uint16_t pixel_count) = 0

Updates pixel count (pure virtual).

Parameters:

pixel_count: New number of pixels

Returns: true if successful

Initialized()

cpp

bool Initialized(void) const

Returns initialization status.

Error()

cpp

esp_err_t Error(void) const

Returns last error code.

Configuration Guide

Basic Setup

Step 1: Include Headers

cpp

#include "TasmotaLED.h"
#include "TasmotaLEDPusher.h"

Step 2: Create Strip Instance

cpp

// For WS2812 RGB strip with 60 LEDs
TasmotaLED strip(ws2812_grb, 60);

// For SK6812 RGBW strip with 100 LEDs
TasmotaLED strip(sk6812_grbw, 100);

// Custom configuration
uint16_t custom_type = TasmotaLed_3_RGB | TasmotaLed_RGB | TasmotaLed_WS2812;
TasmotaLED strip(custom_type, 144);

Step 3: Create and Assign Pusher

cpp

// Auto-select best hardware for GPIO 5
TasmotaLEDPusher *pusher = TasmotaLEDPusher::Create(TasmotaLed_HW_Default, 5);
if (pusher) {
  strip.SetPusher(pusher);
} else {
  // Handle error
}

// Or explicitly request RMT
TasmotaLEDPusher *pusher = TasmotaLEDPusher::Create(TasmotaLed_RMT, 5);

Step 4: Initialize

cpp

if (!strip.Begin()) {
  // Handle initialization error
  Serial.println("Failed to initialize LED strip");
}

Step 5: Use the Strip

cpp

// Set colors
strip.ClearTo(0x000000);           // Clear to black
strip.SetPixelColor(0, 0xFF0000);  // First pixel red
strip.SetPixelColor(1, 0x00FF00);  // Second pixel green
strip.Show();                       // Update strip

Advanced Configuration

Custom LED Type

cpp

// Create custom type: RGB, BGR ordering, WS2812 timing
uint16_t custom_type = TasmotaLed_3_RGB |      // 3 bytes per pixel
                       TasmotaLed_BGR |        // BGR ordering
                       TasmotaLed_WS2812;      // WS2812 timing

TasmotaLED strip(custom_type, 60);

RGBW with W Channel First

cpp

// SK6812 RGBW with W channel before RGB
uint16_t rgbw_type = TasmotaLed_4_WRGB |       // 4 bytes per pixel
                     TasmotaLed_RGB |          // RGB ordering
                     TasmotaLed_Wxxx |         // W first
                     TasmotaLed_SK6812;        // SK6812 timing

TasmotaLED strip(rgbw_type, 100);

Multiple Strips

cpp

// Strip 1 on GPIO 5
TasmotaLED strip1(ws2812_grb, 60);
TasmotaLEDPusher *pusher1 = TasmotaLEDPusher::Create(TasmotaLed_RMT, 5);
strip1.SetPusher(pusher1);
strip1.Begin();

// Strip 2 on GPIO 18
TasmotaLED strip2(sk6812_grbw, 100);
TasmotaLEDPusher *pusher2 = TasmotaLEDPusher::Create(TasmotaLed_RMT, 18);
strip2.SetPusher(pusher2);
strip2.Begin();

Raw Format Mode

cpp

strip.SetRawFormat(true);  // Disable automatic format conversion

// Now buffer must be in strip's native format (e.g., GRB for WS2812)
uint8_t *buf = strip.Pixels();
buf[0] = 0xFF;  // Green
buf[1] = 0x00;  // Red
buf[2] = 0x00;  // Blue
strip.Show();

Compile-Time Configuration

Enable/Disable Hardware Support

In your platformio.ini or build flags:

ini

build_flags = 
  -DTASMOTALED_HARDWARE_RMT=1
  -DTASMOTALED_HARDWARE_SPI=1
  -DTASMOTALED_HARDWARE_I2S=0

Or in your code before including TasmotaLED:

cpp

#define TASMOTALED_HARDWARE_RMT 1
#define TASMOTALED_HARDWARE_SPI 0
#define TASMOTALED_HARDWARE_I2S 0

#include "TasmotaLED.h"

Performance Characteristics

Memory Usage

Per-Strip Overhead

Component	Size	Description
TasmotaLED object	~60 bytes	Class instance
Work buffer	`pixels × size`	Editable buffer (RGB or RGBW)
Show buffer	`pixels × size`	Internal transmission buffer
Pusher object	~40-80 bytes	Hardware implementation
Total	~100 + (2 × pixels × size)

Examples

Configuration	Memory Usage
60 RGB pixels	~460 bytes
144 RGB pixels	~964 bytes
300 RGB pixels	~1,900 bytes
512 RGB pixels	~3,172 bytes
60 RGBW pixels	~580 bytes
144 RGBW pixels	~1,252 bytes

SPI Additional Overhead

SPI requires 3× buffer for encoding:

Configuration	Additional Memory
60 RGB pixels	+540 bytes
144 RGB pixels	+1,296 bytes
300 RGB pixels	+2,700 bytes

Timing Performance

Buffer Operations (512 RGB pixels)

Operation	Time	Notes
`ClearTo(0x000000)`	~15 µs	Optimized memset
`ClearTo(0xFF0000)`	~124 µs	Per-pixel write
`SetPixelColor()`	~0.2 µs	Single pixel
Format conversion	~124 µs	RGB→GRB conversion
`Show()` (RMT)	~16.2 ms	Actual transmission
`Show()` (SPI)	~16.6 ms	Transmission + encoding

Transmission Times

Transmission time depends on pixel count and timing:

WS2812 (30 µs per pixel):

60 pixels: ~1.8 ms
144 pixels: ~4.3 ms
300 pixels: ~9.0 ms
512 pixels: ~15.4 ms

SK6812 (30 µs per pixel):

Similar to WS2812

Maximum Refresh Rate:

60 pixels: ~555 Hz
144 pixels: ~232 Hz
300 pixels: ~111 Hz
512 pixels: ~65 Hz

CPU Overhead

RMT Implementation

Setup: ~100 µs (one-time)
Per Show(): ~150 µs (format conversion + DMA setup)
During transmission: Near zero (DMA handles transfer)
CPU usage: <1% during transmission

SPI Implementation

Setup: ~200 µs (one-time)
Per Show(): ~550 µs (encoding + format conversion)
During transmission: Near zero (DMA handles transfer)
CPU usage: <2% during transmission

Optimization Tips

Minimize Show() Calls

cpp

// Bad: Multiple Show() calls
for (int i = 0; i < 60; i++) {
  strip.SetPixelColor(i, color);
  strip.Show();  // 60 transmissions!
}

// Good: Single Show() call
for (int i = 0; i < 60; i++) {
  strip.SetPixelColor(i, color);
}
strip.Show();  // 1 transmission

Use ClearTo() for Bulk Operations

cpp

// Faster than loop with SetPixelColor()
strip.ClearTo(0xFF0000, 0, 29);  // First 30 pixels red

Check CanShow() Before Show()

cpp

if (strip.CanShow()) {
  strip.Show();
}

Direct Buffer Access for Complex Patterns

cpp

uint8_t *buf = strip.Pixels();
// Direct manipulation (advanced)
for (int i = 0; i < strip.PixelCount() * strip.PixelSize(); i++) {
  buf[i] = pattern[i];
}
strip.Show();

Usage Examples

Basic Initialization

cpp

#include "TasmotaLED.h"
#include "TasmotaLEDPusher.h"

// Create strip instance
TasmotaLED strip(ws2812_grb, 60);

void setup() {
  // Create pusher with auto hardware selection
  TasmotaLEDPusher *pusher = TasmotaLEDPusher::Create(TasmotaLed_HW_Default, 5);
  if (pusher) {
    strip.SetPusher(pusher);
    if (strip.Begin()) {
      // Strip ready
      strip.ClearTo(0x000000);  // Clear to black
      strip.Show();
    }
  }
}

Setting Pixels

cpp

// Set individual pixels
strip.SetPixelColor(0, 0xFF0000);   // Red
strip.SetPixelColor(1, 0x00FF00);   // Green
strip.SetPixelColor(2, 0x0000FF);   // Blue

// Set range of pixels
strip.ClearTo(0xFF0000, 0, 9);      // First 10 pixels red

// Update strip
strip.Show();

RGBW Control

cpp

TasmotaLED strip(sk6812_grbw, 60);

// Pure white using W channel
strip.ClearTo(0xFF000000);  // W=0xFF, RGB=0

// Warm white (W + Red)
strip.ClearTo(0x80FF0000);  // W=0x80, R=0xFF, G=0, B=0

// RGB color (no W)
strip.ClearTo(0x00FF00FF);  // W=0, R=0xFF, G=0, B=0xFF (Magenta)

strip.Show();

Non-Blocking Updates

cpp

void loop() {
  // Check if strip is ready before updating
  if (strip.CanShow()) {
    // Update pixels
    for (int i = 0; i < strip.PixelCount(); i++) {
      strip.SetPixelColor(i, colors[i]);
    }
    strip.Show();
  }
  
  // Other code continues without blocking
}

Integration with Tasmota

Tasmota Light Driver Integration

TasmotaLED is designed to integrate seamlessly with Tasmota's light driver system. Here's how it fits into the Tasmota architecture:

Integration Points

Driver Initialization (FUNC_INIT)

cpp

void TasmotaLEDInit(void) {
  // Create strip based on Settings
  uint16_t led_type = Settings->light_type;
  uint16_t led_count = Settings->light_pixels;
  int8_t gpio = Pin(GPIO_LED);
  
  strip = new TasmotaLED(led_type, led_count);
  
  // Create pusher with hardware auto-selection
  TasmotaLEDPusher *pusher = TasmotaLEDPusher::Create(
    TasmotaLed_HW_Default, gpio);
  
  if (pusher) {
    strip->SetPusher(pusher);
    if (strip->Begin()) {
      AddLog(LOG_LEVEL_INFO, "LED: Initialized %d pixels on GPIO %d", 
             led_count, gpio);
    }
  }
}

Pixel Updates (FUNC_SET_CHANNELS)

cpp

void TasmotaLEDUpdate(void) {
  // Get color data from Tasmota light engine
  for (int i = 0; i < strip->PixelCount(); i++) {
    uint32_t color = GetPixelColorFromLightEngine(i);
    strip->SetPixelColor(i, color);
  }
  
  // Push to hardware
  if (strip->CanShow()) {
    strip->Show();
  }
}

Configuration Changes

cpp

void TasmotaLEDReconfigure(void) {
  // Handle pixel count changes
  if (new_pixel_count != strip->PixelCount()) {
    strip->SetPixelCount(new_pixel_count);
  }
  
  // Handle type changes
  if (new_led_type != strip->GetType()) {
    strip->SetPixelSubType(new_led_type & 0xFF);
  }
}

Tasmota Commands

When integrated with Tasmota, these commands control the LED strip:

Command	Description	Example
`Pixels`	Set number of LEDs	`Pixels 60`
`Scheme`	Set color scheme	`Scheme 2`
`Speed`	Set animation speed	`Speed 10`
`Width`	Set effect width	`Width 1`
`Color`	Set RGB color	`Color #FF0000`
`White`	Set white channel	`White 50`
`Dimmer`	Set brightness	`Dimmer 75`
`Fade`	Enable fade	`Fade 1`

Settings Storage

Tasmota stores LED configuration in Settings structure:

cpp

struct SETTINGS {
  // ...
  uint16_t light_pixels;        // Number of LEDs
  uint8_t  light_type;          // LED type encoding
  uint8_t  light_scheme;        // Animation scheme
  uint8_t  light_speed;         // Animation speed
  uint8_t  light_width;         // Effect width
  // ...
};

Hardware Selection in Tasmota

Tasmota automatically selects the best hardware based on:

SOC Capabilities: Checks what hardware is available
GPIO Availability: Ensures GPIO is not in use
Performance Requirements: Selects RMT for best performance
Fallback: Uses SPI if RMT unavailable

cpp

uint32_t TasmotaSelectHardware(void) {
  uint32_t hw = TasmotaLed_HW_Default;
  
  // Force SPI on ESP32-C2 (no RMT)
  #ifdef CONFIG_IDF_TARGET_ESP32C2
    hw = TasmotaLed_SPI;
  #endif
  
  // User override via SetOption
  if (Settings->flag5.led_use_spi) {
    hw = TasmotaLed_SPI;
  }
  
  return hw;
}

Troubleshooting

Common Issues

1. Strip Not Lighting Up

Symptoms: No LEDs light up after calling Show()

Possible Causes:

Pusher not initialized
Wrong GPIO pin
Incorrect LED type
Power supply issues

Solutions:

cpp

// Check initialization
if (!strip.Begin()) {
  Serial.println("Failed to initialize");
  // Check pusher creation
  if (pusher == nullptr) {
    Serial.println("Pusher creation failed");
  }
}

// Verify GPIO
Serial.printf("Using GPIO %d\n", gpio_pin);

// Test with simple pattern
strip.ClearTo(0xFF0000);  // All red
strip.Show();

2. Wrong Colors

Symptoms: Colors appear incorrect (e.g., red shows as green)

Possible Causes:

Incorrect pixel ordering
Wrong LED type

Solutions:

cpp

// Try different orderings
strip.SetPixelSubType(TasmotaLed_3_RGB | TasmotaLed_RGB);  // RGB
strip.SetPixelSubType(TasmotaLed_3_RGB | TasmotaLed_GRB);  // GRB
strip.SetPixelSubType(TasmotaLed_3_RGB | TasmotaLed_BGR);  // BGR

// Test each ordering
strip.ClearTo(0xFF0000);  // Should be red
strip.Show();

3. Flickering or Glitches

Symptoms: Random flickering, incorrect colors, or partial updates

Possible Causes:

Timing issues
Insufficient power
Long cable runs
Electromagnetic interference

Solutions:

cpp

// Try different timing
uint16_t type_ws2812 = TasmotaLed_3_RGB | TasmotaLed_GRB | TasmotaLed_WS2812;
uint16_t type_sk6812 = TasmotaLed_3_RGB | TasmotaLed_GRB | TasmotaLed_SK6812;

// Check power supply (5V, sufficient amperage)
// Add capacitor (1000µF) across power supply
// Keep data cable short (<1m) or use level shifter

4. Memory Allocation Failures

Symptoms: Begin() returns false, crashes, or resets

Possible Causes:

Too many LEDs for available memory
Memory fragmentation

Solutions:

cpp

// Check available heap
Serial.printf("Free heap: %d bytes\n", ESP.getFreeHeap());

// Calculate required memory
uint32_t required = strip.PixelCount() * strip.PixelSize() * 2;
Serial.printf("Required: %d bytes\n", required);

// Reduce pixel count if necessary
if (required > ESP.getFreeHeap() / 2) {
  strip.SetPixelCount(smaller_count);
}

5. Performance Issues

Symptoms: Slow updates, low frame rate

Possible Causes:

Too many Show() calls
Inefficient pixel updates
Wrong hardware selection

Solutions:

cpp

// Batch updates
for (int i = 0; i < strip.PixelCount(); i++) {
  strip.SetPixelColor(i, colors[i]);
}
strip.Show();  // Single show call

// Use ClearTo() for bulk operations
strip.ClearTo(0xFF0000, 0, 29);  // Faster than loop

// Check hardware
Serial.printf("Using hardware: 0x%08X\n", hw_type);

// Verify CanShow() before Show()
if (strip.CanShow()) {
  strip.Show();
}

Debug Logging

Enable debug logging to diagnose issues:

cpp

// In Tasmota, set log level
SerialLog 4  // Debug level

// Look for these messages:
// LED: RMT gpio 5
// LED: SPI gpio 5
// LED: Error create RMT bus failed 5 err=XXX

Hardware-Specific Issues

ESP32-C2

Only SPI supported (no RMT)
Ensure TASMOTALED_HARDWARE_SPI is enabled

ESP32-S2/S3

RMT channels limited to 4
Check channel availability if using multiple strips

ESP32 Classic

RMT channels limited to 8
Most flexible hardware support

Timing Verification

Verify timing with oscilloscope or logic analyzer:

WS2812 Expected:

T0H: 400ns ±150ns
T0L: 850ns ±150ns
T1H: 800ns ±150ns
T1L: 450ns ±150ns
Reset: >50µs

SK6812 Expected:

T0H: 300ns ±150ns
T0L: 900ns ±150ns
T1H: 600ns ±150ns
T1L: 600ns ±150ns
Reset: >80µs

Appendix

Pixel Order Matrix

The library uses a lookup table for pixel ordering:

cpp

static const uint8_t TASMOTALED_CHANNEL_ORDERS[8][3] = {
  {1, 0, 2},  // Def=GRB (0)
  {1, 0, 2},  // GRB (1)
  {0, 1, 2},  // RGB (2)
  {0, 2, 1},  // RBG (3)
  {2, 1, 0},  // BRG (4)
  {1, 2, 0},  // BGR (5)
  {2, 0, 1},  // GBR (6)
  {1, 0, 2}   // GRB (7) - fallback
};

Interpretation:

Index 0: Position of Red channel
Index 1: Position of Green channel
Index 2: Position of Blue channel

Example: GRB ordering {1, 0, 2} means:

Red goes to position 1
Green goes to position 0
Blue goes to position 2
Result: G(0) R(1) B(2)

Timing Structure

cpp

typedef struct TasmotaLED_Timing {
  uint16_t T0H;    // Bit 0 high time (nanoseconds)
  uint16_t T0L;    // Bit 0 low time (nanoseconds)
  uint16_t T1H;    // Bit 1 high time (nanoseconds)
  uint16_t T1L;    // Bit 1 low time (nanoseconds)
  uint32_t Reset;  // Reset time (nanoseconds)
} TasmotaLED_Timing;

Comparison with NeoPixelBus

Feature	TasmotaLED	NeoPixelBus
Memory	Lower (2 buffers)	Higher (3+ buffers)
Code Size	~15 KB	~40 KB
Hardware	RMT, SPI, I2S	RMT, I2S, UART, BitBang
ESP8266	❌ No	✅ Yes
ESP32	✅ Yes	✅ Yes
Buffer Swap	No (copy on Show)	Yes (double buffering)
Dirty Flag	Ignored	Used
API	Similar	Full-featured
Performance	Optimized	Feature-rich

License

TasmotaLED - Lightweight implementation for addressable LEDs
Copyright (C) 2024 Stephan Hadinger

This library is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

Revision History

Version	Date	Changes
1.0	2024	Initial release with RMT and SPI support

End of Documentation

TasmotaLED Library Documentation

TasmotaLED Library Documentation

Executive Summary

Table of Contents

Architecture Overview

Design Philosophy

System Architecture

Memory Management

Class Hierarchy

Class Diagram

LED Type Encoding System

Type Encoding Structure

Pixel Size Encoding (Bits 0-3)

Pixel Order Encoding (Bits 4-6)

W Channel Position (Bit 7)

Timing Code (Bits 8-15)

Predefined LED Types

Type Encoding Examples

Hardware Acceleration

Hardware Support Matrix

Hardware Selection

Hardware Resolution Priority

Compile-Time Configuration

RMT Implementation

SPI Implementation

I2S Implementation

API Reference

TasmotaLED Class

Constructor

Destructor

Initialization Methods

SetPusher()

Begin()

Pixel Manipulation Methods

SetPixelColor()

GetPixelColor()

ClearTo()

Show()

CanShow()

Configuration Methods

SetPixelCount()

SetPixelSubType()

SetRawFormat()

Query Methods

PixelCount()

PixelSize()

GetType()

Pixels()

IsDirty()

Dirty()

TasmotaLEDPusher Class (Abstract)

Static Factory Methods

Create()

ResolveHardware()

Instance Methods

Begin()

Push()

CanShow()

SetPixelCount()

Initialized()

Error()

Configuration Guide

Basic Setup

Step 1: Include Headers

Step 2: Create Strip Instance

Step 3: Create and Assign Pusher

Step 4: Initialize

Step 5: Use the Strip

Advanced Configuration

Custom LED Type

RGBW with W Channel First

Multiple Strips

Raw Format Mode

Compile-Time Configuration

Enable/Disable Hardware Support

Performance Characteristics

Memory Usage

Per-Strip Overhead

Examples

SPI Additional Overhead