LED Matrix Display

Explore an 8x8 LED matrix display system for learning, simulating, and validating 2D pixel graphics, character rendering, row-column multiplexing, and animation control.

Display LED Matrix 8x8 GPIO Multiplexing

Overview Theory Architecture Source Code Pinout Examples

Overview

Imagine a miniature, programmable digital billboard—an interactive 8x8 LED matrix boasting a compact capacity of 64 individually addressable pixels, perfectly crafted for learning, testing, and visualizing 2D graphics and control algorithms.

Even within this concise 64-pixel canvas, you can unlock incredible creativity: design custom character sets, test low-level GPIO register logic, or master the art of row-and-column multiplexing to drive the entire grid efficiently.

Using embedded C firmware, you can orchestrate high-speed scanning and smooth frame refreshes to instantly bring your patterns, icons, and animations to life.

Quick Facts

Theory

An LED matrix is a two-dimensional arrangement of LEDs controlled using row and column driver signals. Instead of controlling every LED individually, the display uses multiplexing to reduce the number of required control signals.

The LED Matrix Display uses eight row driver lines and eight column data lines. One row is enabled at a time while the required column pattern is written.

Multiplexing Method

Active Row Scanning

Enable Row 0

→

Write 8 Columns

→

Delay 1 ms

→

Next Row

Row Scanning

The firmware enables one row at a time and writes the corresponding eight-bit column data pattern. The process is repeated continuously across all eight rows.

for each row:

    enable_row(row);

    write_columns(pattern[row]);

    delay_us(1000);

    disable_row(row);

Frame Refresh

Each row is scanned for approximately 1 ms. Scanning all eight rows produces a complete frame refresh of approximately 8 ms, corresponding to a frame refresh rate of about 125 Hz.

Architecture

The LED Matrix Display system consists of the embedded firmware, two GPIO register blocks, row drivers, column drivers, and the 8x8 LED matrix.

Firmware

→

GPIO0

→

Row Drivers

Firmware

→

GPIO1

→

Column Drivers

Row Drivers

Column Drivers

→

8x8 LED Matrix

System Components

8x8 LED display matrix
8 row driver lines
8 column driver lines
GPIO0 register block
GPIO1 register block
Multiplexed frame refresh
Integrated simulator and matrix visualizer

Source Code

Example GPIO configuration for the LED Matrix Display.

GPIO0 Configuration

// GPIO0: All bits configured as outputs
// Row driver signals ROW0 - ROW7

WRITE_REGISTER(0x40000000, 0xFF);

GPIO1 Configuration

// GPIO1: All bits configured as outputs
// Column driver signals COL0 - COL7

WRITE_REGISTER(0x40000400, 0xFF);

Row Scanning

// Enable one row at a time
// Write column data
// Wait 1 ms before scanning next row

delay_us(1000);

Firmware Entrypoint

void fw_main(void)
{
    // Configure GPIO0
    WRITE_REGISTER(0x40000000, 0xFF);

    // Configure GPIO1
    WRITE_REGISTER(0x40000400, 0xFF);

    // Start matrix scanning

    while (1)
    {
        // Row scanning
        // Column pattern update

        delay_us(1000);
    }
}

Pinout

GPIO register mapping for the LED Matrix row and column driver signals.

GPIO0 - Row Drivers

Bit 0
ROW0

Bit 1
ROW1

Bit 2
ROW2

Bit 3
ROW3

Bit 4
ROW4

Bit 5
ROW5

Bit 6
ROW6

Bit 7
ROW7

GPIO1 - Column Drivers

Bit 0
COL0

Bit 1
COL1

Bit 2
COL2

Bit 3
COL3

Bit 4
COL4

Bit 5
COL5

Bit 6
COL6

Bit 7
COL7

Register Addresses

GPIO0 MODE
0x40000000

GPIO0 IN
0x40000004

GPIO0 OUT
0x40000008

GPIO1 MODE
0x40000400

GPIO1 IN
0x40000404

GPIO1 OUT
0x40000408

Examples

Example exercises for the LED Matrix Display system.

Display a single pixel
Display a complete row
Display a complete column
Create custom 8x8 pixel patterns
Render characters on the matrix
Implement row scanning multiplexing
Create LED animations
Control column data using GPIO1
Validate frame refresh behavior