MAX7219 8x8 LED Matrix

Welcome to the 8×8 LED Matrix Lab

Monty waving welcome An 8×8 LED matrix is a grid of 64 tiny lights. You can draw letters, shapes, and animations — all with just 4 wires! Let's build something amazing!

What Is an 8×8 LED Matrix?

An 8×8 LED matrix is a grid of 64 Light-Emitting Diodes (LEDs) arranged in 8 rows and 8 columns. A single driver chip called the MAX7219 controls all 64 LEDs. This keeps the wiring simple — you only need 4 wires between the Pico and the display.

This low-cost ($3) device is perfect for small projects that do not need a full graphical screen. You will be surprised at how creative you can be with just 64 pixels!

eBay Search for "MAX7219 8x8 matrix"

The device has five connectors:

Power (VCC) — connects to 3.3 V or 5 V
Ground (GND) — connects to GND
Clock (SCK) — the timing signal for Serial Peripheral Interface (SPI) communication
Data (MOSI — Master Out Slave In) — carries the data signal
Chip Select (CS) — tells the chip when to listen

You communicate with the device using SPI. SPI is a way for two chips to share data using 3 or 4 wires. The Pico sends data, and the MAX7219 receives it and lights up the right LEDs.

There is also an easy-to-use driver library by Mike Causer. Download this file and copy it to your Pico before running the examples below.

Wiring Steps

Connect VCC on the matrix to 3.3 V on the Pico.
Connect GND on the matrix to any GND pin on the Pico.
Connect SCK on the matrix to GP2 on the Pico.
Connect MOSI (data) on the matrix to GP3 on the Pico.
Connect CS on the matrix to GP4 on the Pico.

Quick Start: Show a Letter

Here is how you set up the driver and display one letter:

from machine import SPI, Pin    # import SPI for communication, Pin for the CS pin
import max7219                   # import the MAX7219 driver library
from utime import sleep          # import sleep for delays

CLOCK_PIN = 2    # GP2 — SPI clock
DATA_PIN  = 3    # GP3 — SPI data (MOSI)
CS_PIN    = 4    # GP4 — Chip Select

# Set up the SPI bus using bus 0
spi0 = SPI(0, baudrate=10000000, polarity=1, phase=0,
           sck=Pin(CLOCK_PIN), mosi=Pin(DATA_PIN))

cs = Pin(CS_PIN, Pin.OUT)   # set up the Chip Select pin as an output

# Create the matrix object — the "1" means we have 1 display
matrix = max7219.Matrix8x8(spi0, cs, 1)

# Display the letter A at position x=0, y=0 with LEDs on (1)
matrix.text('A', 0, 0, 1)
matrix.show()   # send the image to the display

What Each Line Does

Line	Purpose
`SPI(0, baudrate=10000000, ...)`	Sets up the SPI bus at 10 MHz on bus 0
`Pin(CS_PIN, Pin.OUT)`	Sets the Chip Select pin as an output
`max7219.Matrix8x8(spi0, cs, 1)`	Creates a matrix object for 1 display
`matrix.text('A', 0, 0, 1)`	Draws the letter A at column 0, row 0
`matrix.show()`	Sends all the pixel data to the display

Using Multiple Displays

You can chain up to 4 displays side by side. Change the last number in Matrix8x8() to match how many displays you have:

import max7219
from machine import Pin, SPI

spi = SPI(0, baudrate=10000000, polarity=1, phase=0,
          sck=Pin(2), mosi=Pin(3))     # set up the SPI bus
cs = Pin(4, Pin.OUT)                   # set up Chip Select

# The "4" at the end tells the driver we have 4 displays chained together
matrix = max7219.Matrix8x8(spi, cs, 4)

matrix.text('1234', 0, 0, 1)   # display "1234" across all 4 displays
matrix.show()                   # send the image to the displays

Key Idea

Monty thinking When you chain displays, data flows from one display to the next like a relay race. The Pico sends data to display 1, which passes extra data to display 2, and so on. That is why 4 displays still only need 4 wires!

Basic Program

from machine import SPI, Pin    # import SPI and Pin
import max7219                   # import the MAX7219 driver
from utime import sleep          # import sleep for delays

CLOCK_PIN  = 2    # GP2 — SPI clock
DATA_PIN   = 3    # GP3 — SPI data
CS_PIN     = 4    # GP4 — Chip Select
delay_time = 1    # wait 1 second between each display step

# Set up SPI bus 0
spi0 = SPI(0, baudrate=10000000, polarity=1, phase=0,
           sck=Pin(CLOCK_PIN), mosi=Pin(DATA_PIN))

cs = Pin(CS_PIN, Pin.OUT)   # Chip Select as output

matrix = max7219.Matrix8x8(spi0, cs, 1)   # one display

matrix.text('A', 0, 0, 1)   # draw the letter A
matrix.show()                # send to the display
sleep(delay_time)            # wait 1 second

Full Demo

This program cycles through several different displays to show what the matrix can do:

from machine import SPI, Pin    # import SPI and Pin
import max7219                   # import the MAX7219 driver
from utime import sleep          # import sleep for delays

# Set up SPI bus 0 with clock on GP2 and data on GP3
spi0 = SPI(0, baudrate=10000000, polarity=1, phase=0,
           sck=Pin(2), mosi=Pin(3))

cs = Pin(4, Pin.OUT)   # Chip Select on GP4

matrix = max7219.Matrix8x8(spi0, cs, 1)   # one display

delay_time = 1   # seconds to show each image

while True:
    # --- Step 1: draw the letter A ---
    matrix.text('A', 0, 0, 1)   # place 'A' at top-left corner
    matrix.show()                # send to display
    sleep(delay_time)

    # --- Step 2: draw an X using two diagonal lines ---
    matrix.fill(0)               # clear all pixels (0 = off)
    matrix.line(0, 0, 7, 7, 1)  # draw a line from top-left to bottom-right
    matrix.show()
    sleep(delay_time)

    matrix.line(7, 0, 0, 7, 1)  # draw a line from top-right to bottom-left
    matrix.show()
    sleep(delay_time)

    # --- Step 3: add a box around the X ---
    matrix.rect(0, 0, 8, 8, 1)  # draw an 8×8 rectangle border
    matrix.show()
    sleep(delay_time)

    matrix.fill(0)   # clear all pixels

    # --- Step 4: draw a smile face using individual pixels ---
    matrix.pixel(1, 1, 1)   # left eye
    matrix.pixel(6, 1, 1)   # right eye
    matrix.pixel(0, 4, 1)   # left cheek
    matrix.pixel(7, 4, 1)   # right cheek
    matrix.pixel(1, 5, 1)   # smile left
    matrix.pixel(6, 5, 1)   # smile right
    matrix.pixel(2, 6, 1)   # smile lower-left
    matrix.pixel(5, 6, 1)   # smile lower-right
    matrix.pixel(3, 7, 1)   # smile bottom-left
    matrix.pixel(4, 7, 1)   # smile bottom-right
    matrix.show()
    sleep(delay_time)

    matrix.fill(0)   # clear all pixels
    matrix.show()    # update the display to show the blank screen
    sleep(delay_time)

What Each Line Does

Line	Purpose
`matrix.fill(0)`	Turns off all 64 pixels
`matrix.line(0, 0, 7, 7, 1)`	Draws a line from (col 0, row 0) to (col 7, row 7)
`matrix.rect(0, 0, 8, 8, 1)`	Draws a rectangle border starting at (0,0) that is 8 wide and 8 tall
`matrix.pixel(x, y, 1)`	Turns on one pixel at column x, row y
`matrix.show()`	Sends all pixel changes to the display

Monty's Tip

Monty giving a tip Try changing the numbers in matrix.pixel() to create your own face or design. The columns go from 0 (left) to 7 (right). The rows go from 0 (top) to 7 (bottom).

Great Work!

Monty celebrating You drew letters, lines, rectangles, and a smile face on an 8×8 LED matrix! Next, try the 4-Digit LED Display lab to build a working clock.