B4R Library rArduinoLEDMatrix

rwblinn · Aug 27, 2026

B4R Library rArduinoLEDMatrix

Brief
rArduinoLEDMatrix is an open-source library wrapper for the built-in 12x8 LED Matrix on the Arduino UNO R4 WiFi board, specifically optimized for high-performance 2D rendering, native text scrolling, and vector geometric shapes.

Purpose

Provides a high-level B4R abstraction layer for the native Renesas RA4M1 hardware matrix.
Integrates seamless vector line, rectangle, and circle drawing loops with automatic canvas clearing.
Exposes built-in factory flash memory icons using professional uppercase constant syntax.
Enables smooth, speed-regulated horizontal text scrolling via the ArduinoGraphics core framework.

Development Info
This B4R library is:

An Arduino_LED_Matrix and ArduinoGraphics library wrapper.
Written in C++ using Arduino IDE 2.3.10 and the B4Rh2xml / XMLTool parsing pipeline.
Depends on (minimum version) the platform Arduino UNO R4 Boards (1.6.0) and native libraries Arduino_LED_Matrix (2.3.8+) and ArduinoGraphics (1.1.5+).
Tested with Arduino UNO R4 WiFi (32-bit Renesas RA4M1 architecture, 5V logic).
Tested with B4R 4.00 (64-bit).
Not supported: Animations.

Screenshots
Arduino UNO R4 WiFi onboard 12x8 LED Matrix display, powered directly via the USB-C interface.

Compatibility

Supports boards based on the Arduino UNO R4 architecture featuring the 12x8 Charlieplexed LED matrix array.

Files
The rArduinoLEDMatrix.zip archive contains the compiled library assets (.h, .cpp, .xml) and multiple usage examples.

Install
Copy the rArduinoLEDMatrix library folder from the ZIP into your B4R Additional Libraries folder, keeping the directory structure intact.
Ensure the core underlying ArduinoGraphics library is installed using your Arduino IDE libraries manager first.
Several examples can be found in the folder examples.

Functions

Initialize
Initializes the LED matrix peripheral and fires up the background multiplexing hardware driver.
SetPixel (X As Byte, Y As Byte, TurnOn As Byte)
Toggles a single isolated pixel coordinate. X ranges from 0 to 11 (left to right), Y ranges from 0 to 7 (top to bottom). Set TurnOn to 1 to illuminate, 0 to turn off.
Clear
Wipes the internal frame representation buffer instantly, turning off all matrix lines.
DrawFrame (FrameData() As Byte)
Draws a full custom frame on the screen using a flattened 1D B4R byte array containing exactly 96 elements (8 rows * 12 columns).
PrintText (Text As String, X As Int, Y As Int, Direction As Byte, ScrollSpeedMS As ULong)
Renders strings using the native vector-graphics engine.
- X, Y: Starting coordinate anchors (use 0, 1 for centered scrolling text).
- Direction: 0 = Static Text, 1 = Scroll Left, 2 = Scroll Right.
- ScrollSpeedMS: Scrolling pacing animation delay in milliseconds (e.g., 50 to 100).
DrawLine (X1 As Int, Y1 As Int, X2 As Int, Y2 As Int, TurnOn As Byte)
Draws a sharp vector line between two coordinates. Wipes previous canvas elements before drawing.
DrawRect (X As Int, Y As Int, Width As Int, Height As Int, TurnOn As Byte)
Draws an empty bounding rectangle layout framework on the display grid.
DrawCircle (X As Int, Y As Int, Radius As Int, TurnOn As Byte)
Draws an empty geometric circle perimeter centered around focal location coordinate (X, Y).
LoadFrame (FrameAddress As ULong)
Loads an official, factory pre-defined stock icon asset from flash memory into the background rendering register via its direct memory address pointer mapping.
ScrollText (Text As String, SpeedMS As ULong)
A custom software text scrolling implementation that shifts an uppercase text string from right to left using local bit-shifting logic frames synchronously.

Constants (Property Getters)
The following read-only public property methods provide clean autocomplete matching the factory image tokens inside the core gallery.h firmware:

ICON_BLUETOOTH As ULong - Bluetooth logo
ICON_BOOTLOADER_ON As ULong - Bootloader active symbol
ICON_CHIP As ULong - Integrated circuit microchip icon
ICON_CLOUD_WIFI As ULong - Wi-Fi cloud networking symbol
ICON_DANGER As ULong - Warning/Alert triangular exclamation mark
ICON_EMOJI_BASIC As ULong - Standard smiley face
ICON_EMOJI_HAPPY As ULong - Large smiling grin emoji
ICON_EMOJI_SAD As ULong - Frowned sad face emoji
ICON_HEART_BIG As ULong - Large heart symbol
ICON_HEART_SMALL As ULong - Smaller localized heart layout
ICON_LIKE As ULong - Thumbs-up review confirmation icon
ICON_MUSIC_NOTE As ULong - Musical eighth-note icon

Example

Code:

Sub Process_Globals
    Private VERSION As String = "rArduinoLEDMatrix Basic v20260827"
    ' Communication
    Public Serial1 As Serial
    ' Matrix
    Private Matrix As ArduinoLEDMatrix
End Sub

Private Sub AppStart
    Serial1.Initialize(115200)
    Log(CRLF, "[AppStart] ", VERSION)
    ' Matrix init and clear
    Matrix.Initialize
    Matrix.Clear
  
    ' Display a native stock emoji constant frame
    Log("Loading stock emoji icon...")
    Matrix.LoadFrame(Matrix.ICON_EMOJI_HAPPY)
    Delay(2000)
  
    ' Clear canvas and draw a vector geometric circle
    Log("Drawing vector circle shape...")
    Matrix.Clear
    Matrix.DrawCircle(5, 3, 3, 1) ' Centered at X=5, Y=3 with 3px Radius
    Delay(2000)
  
    ' Trigger a hardware-accelerated text scroll loop
    Log("Streaming vector text scroll sequence...")
    Matrix.Clear
    Matrix.PrintText(" B4R UNO R4 WI-FI ", 0, 1, Matrix.TEXT_SCROLL_LEFT, 500)
End Sub

Troubleshooting

Text Artifacts ("|"): Ensure you pass Direction = 0 only when intending to print static text frames. The internal engine auto-appends newline structural padding to drop border errors cleanly.
ArduinoGraphics Include Order: If manually editing source architectures, ArduinoGraphics.h must always be declared before Arduino_LED_Matrix.h or compilation throws a token error.
Memory Clear: Geometric objects automatically wipe out previous frames using a structural context layout refresh. Call Matrix.Clear manually if transitioning between custom flat arrays or vector loops.

License
MIT License - see LICENSE file.

Credits

Developers & maintainers of the official Arduino UNO R4 Core Architecture Framework and native vector display libraries.

Disclaimer

All product names, logos, and brands are property of their respective owners.

B4R Library rArduinoLEDMatrix

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