LED Matrix

I2C

output

Medium RAM

2.4.0

#Description

A small display consisting of LEDs. It is great for pixelated images and data.

#Links

Open Wiki for Grove ComponentGet the Grove Component

#Aliases

• MY9221

#Functions

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#JavaScript / Node.js

@blokdots/components on npm ↗

ClassLEDMatrixextends I2cComponentBase

LEDMatrix component for controlling Grove RGB LED Matrix w/Driver (8x8 RGB matrix). Uses I2C communication (address 0x65) with built-in STM32F031 controller.

#Value type

TypeScript

interface LEDMatrixValue {
  power: boolean;
  type: "bitmap" | "full-color" | "text" | "animation";
  color: string;
  text: string;
  bitmap: number[];
  displayDuration: number;
  animation: number;
}

#Constructor options

Option	Type	Required	Description	Inherited from
orientation	number	optional	—
pin	I2CPinID	required	—	I2cComponentBase

#Events

Event	Parameters	Description
change	value: LEDMatrixValue	—

#Methods

setColor(color: string)

Set entire matrix to a single RGB color.

displayText(text: string, durationMs: number, colorName: string)

Display scrolling text with specified color name and duration.

displayNumber(num: number, durationMs: number, colorName: string)

Display a number with specified color name and duration.

displayAnimation(animationId: number, durationMs: number)

Play a built-in color animation.

displayColorWave(colorName: string, durationMs: number)

Display color wave animation.

displayColorBar(percent: number)

Display color bar at specified percentage.

displayEmoji(emojiIndex: number)

Display built-in emoji by index.

drawBitmap(bitmap: number[])

Draw a custom 8x8 bitmap.

clear()

Turn off all LEDs (clear display).

powerOff()

Power off the matrix (alias for clear).

get i2cId→ I2CPinIDfrom I2cComponentBase

The resolved I2C pin ID (e.g. "i2c-0"). Useful for logging or passing back to the Arduino sketch.

#Example

JavaScript

import { Board, LEDMatrix } from "@blokdots/components";

const board = new Board("/dev/ttyACM0");
await board.open();

const lEDMatrix = new LEDMatrix({ board, pin: "example" });

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#C++ (Arduino)

ClassLEDMatrixextends ComponentBase

Direct I2C implementation for the Grove RGB LED Matrix (STM32F031 + MY9221). 8x8 RGB LED Matrix with built-in MCU controller. This class communicates directly via I2C without requiring external libraries. Based on the Seeed Studio protocol: https://github.com/Seeed-Studio/Seeed_RGB_LED_Matrix Supported operations: - setFullColor(r, g, b) - Set entire matrix to single RGB color - setFullColor(Color) - Set entire matrix using blokdots::Color - displayText(text, duration, color) - Display scrolling text with color name - displayNumber(num, duration, color)- Display a number with color name - displayAnimation(id, duration) - Play built-in color animation by ID - clear() - Turn off all LEDs - powerOff() - Alias for clear() Animation IDs: - 0: big square - 1: small square - 2: rainbow cycle - 3: fire - 4: walking child - 5: broken heart Text colors: - "red", "orange", "yellow", "green", "cyan", "blue", "purple", "pink", "white", "black" Note: This component uses I2C communication (default address 0x65).

#Required libraries

• #include <Wire.h> — Wire

#Setup

C++

#include "blokdots.h"

LEDMatrix myComponent();

#Constructor

LEDMatrix(orientation, wire)

Basic constructor (no EventBus)

Parameter	Type	Default
orientation	uint8_t	3
wire	TwoWire	Wire

LEDMatrix(bus, orientation, evtChange, wire)

Constructor with EventBus for trigger support

Parameter	Type	Default
bus	EventBus	required
orientation	uint8_t	required
evtChange	uint8_t	required
wire	TwoWire	Wire

#Methods

setFullColor(r, g, b)

Set entire matrix to a single RGB color

Parameter	Type	Default
r	uint8_t	required
g	uint8_t	required
b	uint8_t	required

setFullColor(c)

blokdots::Color overload

Parameter	Type	Default
c	blokdots::Color	required

setFullColor(hex)

Hex color support

Parameter	Type	Default
hex	const char	required

displayText(text, durationMs, colorName)

Display scrolling text with specified color name and duration (in milliseconds)

Parameter	Type	Default
text	const char	required
durationMs	uint32_t	required
colorName	const char	required

displayNumber(num, durationMs, colorName)

Display a number with specified color name and duration (in milliseconds)

Parameter	Type	Default
num	int16_t	required
durationMs	uint32_t	required
colorName	const char	required

displayEmoji(emojiIndex)

Display built-in emoji by index

Parameter	Type	Default
emojiIndex	uint8_t	required

displayAnimation(animationId, durationMs)

3 = fire, 4 = walking child, 5 = broken heart

Parameter	Type	Default
animationId	uint8_t	required
durationMs	uint32_t	required

displayColorWave(colorName, durationMs)

Display color wave animation with specified color name and duration

Parameter	Type	Default
colorName	const char	required
durationMs	uint32_t	required

displayColorBar(percent)

Display color bar at specified percentage (0-100)

Parameter	Type	Default
percent	uint8_t	required

writePixel(index, value)

Stage a single pixel value into the bitmap buffer (index 0-63, row by row)

Parameter	Type	Default
index	uint8_t	required
value	uint8_t	required

commitBitmap()

1ms delay between each write (required by the controller).

clear()

powerOff()

isOn()→ bool

emittedValue()→ int

For triggers: returns 1 when powered on, 0 when off