8x8 LED Matrix MAX7219 with Raspberry Pi Pico Circuit & Code

Introduction

In this tutorial, we will be using an 8×8 LED matrix that is controlled by a MAX7219 chip. We will be using a Raspberry Pi Pico as our microcontroller and we will be programming it in MicroPython. This project is a great intro to using LED matrix and the MAX7219 chip.

Required Components

Raspberry Pi Pico
8×8 LED matrix
jumper wire
breadboard

MAX7219 LED Dot Matrix Display

The dot-matrix display is an electrical device that can show information on machines, clocks, and many other devices. In this project, we will use the Raspberry Pi Pico to control the 8×8 LED dot matrix to make a heart pattern.

The MAX7219 SPI interface allows you to control the module with just a few wires, making it perfect for use with Raspberry Pi Pico. Getting Started Raspberry Pi Pico – Pinout, Specs – Beginner Guide

This module can be used to control an 8×8 LED matrix or 64 individual LEDs. You can use it to create animations, games, or any other creative project. The module is easy to use and only requires a few wires to connect it to your project. The MAX7219 comes with a built-in voltage regulator so it can be powered by either a 5V or 3.3V power supply.

MAX7219 Dot Led Matrix Pinout

The LED matrix can be done through two driving modes. They are parallel (where each row or column is sent with parallel data) and serial (where the data is sent serially and an IC is operated to convert this serial data into parallel data).

Schematic Diagram – 8×8 LED Matrix MAX7219 With Raspberry Pi Pico

MAX7219	Pico Name	Pico GPIO	Pico PIN
VCC	VBUS		40
GND	GND		38
DIN	MOSI (SPI0 TX)	GP7	10
CS	SPI0 CSn	GP5	7
CLK	SCK	GP6	9

Micropython Code & Libraries

This 8×8 LED Matrix Library module will be interfaced with Raspberry Pi Pico for displaying alphabets, symbols & logos. First, we require to download a micropython library specifically designed for LED MATRIX. Getting Started With Raspberry Pi Pico With Thonny IDE

Installing MAX7219 MicroPython Library

Open a new tab in Thonny IDE. Copy the code here. Save it to Raspberry Pi Pico with the name max7219.py under the lib folder.

max7219.py

The below libraries allow you to control the max7219 LED driver with a variety of different commands.

"""
MicroPython max7219 cascadable 8x8 LED matrix driver
https://github.com/mcauser/micropython-max7219

MIT License
Copyright (c) 2017 Mike Causer

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
"""
"""
MicroPython max7219 cascadable 8x8 LED matrix driver
https://github.com/mcauser/micropython-max7219

MIT License
Copyright (c) 2017 Mike Causer

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
"""

from micropython import const
import framebuf

_NOOP = const(0)
_DIGIT0 = const(1)
_DECODEMODE = const(9)
_INTENSITY = const(10)
_SCANLIMIT = const(11)
_SHUTDOWN = const(12)
_DISPLAYTEST = const(15)

class Matrix8x8:
    def __init__(self, spi, cs, num):
        """
        Driver for cascading MAX7219 8x8 LED matrices.

        >>> import max7219
        >>> from machine import Pin, SPI
        >>> spi = SPI(1)
        >>> display = max7219.Matrix8x8(spi, Pin('X5'), 4)
        >>> display.text('1234',0,0,1)
        >>> display.show()

        """
        self.spi = spi
        self.cs = cs
        self.cs.init(cs.OUT, True)
        self.buffer = bytearray(8 * num)
        self.num = num
        fb = framebuf.FrameBuffer(self.buffer, 8 * num, 8, framebuf.MONO_HLSB)
        self.framebuf = fb
        # Provide methods for accessing FrameBuffer graphics primitives. This is a workround
        # because inheritance from a native class is currently unsupported.
        # http://docs.micropython.org/en/latest/pyboard/library/framebuf.html
        self.fill = fb.fill  # (col)
        self.pixel = fb.pixel # (x, y[, c])
        self.hline = fb.hline  # (x, y, w, col)
        self.vline = fb.vline  # (x, y, h, col)
        self.line = fb.line  # (x1, y1, x2, y2, col)
        self.rect = fb.rect  # (x, y, w, h, col)
        self.fill_rect = fb.fill_rect  # (x, y, w, h, col)
        self.text = fb.text  # (string, x, y, col=1)
        self.scroll = fb.scroll  # (dx, dy)
        self.blit = fb.blit  # (fbuf, x, y[, key])
        self.init()

    def _write(self, command, data):
        self.cs(0)
        for m in range(self.num):
            self.spi.write(bytearray([command, data]))
        self.cs(1)

    def init(self):
        for command, data in (
            (_SHUTDOWN, 0),
            (_DISPLAYTEST, 0),
            (_SCANLIMIT, 7),
            (_DECODEMODE, 0),
            (_SHUTDOWN, 1),
        ):
            self._write(command, data)

    def brightness(self, value):
        if not 0 <= value <= 15:
            raise ValueError("Brightness out of range")
        self._write(_INTENSITY, value)

    def show(self):
        for y in range(8):
            self.cs(0)
            for m in range(self.num):
                self.spi.write(bytearray([_DIGIT0 + y, self.buffer[(y * self.num) + m]]))
            self.cs(1)

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"""

MicroPython max7219 cascadable 8x8 LED matrix driver

https://github.com/mcauser/micropython-max7219

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy

of this software and associated documentation files (the "Software"), to deal

in the Software without restriction, including without limitation the rights

to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

copies of the Software, and to permit persons to whom the Software is

furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all

copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

SOFTWARE.

"""

MicroPython max7219 cascadable 8x8 LED matrix driver

https://github.com/mcauser/micropython-max7219

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy

of this software and associated documentation files (the "Software"), to deal

in the Software without restriction, including without limitation the rights

to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

copies of the Software, and to permit persons to whom the Software is

furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all

copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

SOFTWARE.

"""

from micropython import const

import framebuf

_NOOP = const(0)

_DIGIT0 = const(1)

_DECODEMODE = const(9)

_INTENSITY = const(10)

_SCANLIMIT = const(11)

_SHUTDOWN = const(12)

_DISPLAYTEST = const(15)

class Matrix8x8:

def __init__(self, spi, cs, num):

"""

Driver for cascading MAX7219 8x8 LED matrices.

>>> import max7219

>>> from machine import Pin, SPI

>>> spi = SPI(1)

>>> display = max7219.Matrix8x8(spi, Pin('X5'), 4)

>>> display.text('1234',0,0,1)

>>> display.show()

"""

self.spi = spi

self.cs = cs

self.cs.init(cs.OUT, True)

self.buffer = bytearray(8 * num)

self.num = num

fb = framebuf.FrameBuffer(self.buffer, 8 * num, 8, framebuf.MONO_HLSB)

self.framebuf = fb

# Provide methods for accessing FrameBuffer graphics primitives. This is a workround

# because inheritance from a native class is currently unsupported.

# http://docs.micropython.org/en/latest/pyboard/library/framebuf.html

self.fill = fb.fill # (col)

self.pixel = fb.pixel # (x, y[, c])

self.hline = fb.hline # (x, y, w, col)

self.vline = fb.vline # (x, y, h, col)

self.line = fb.line # (x1, y1, x2, y2, col)

self.rect = fb.rect # (x, y, w, h, col)

self.fill_rect = fb.fill_rect # (x, y, w, h, col)

self.text = fb.text # (string, x, y, col=1)

self.scroll = fb.scroll # (dx, dy)

self.blit = fb.blit # (fbuf, x, y[, key])

self.init()

def _write(self, command, data):

self.cs(0)

for m in range(self.num):

self.spi.write(bytearray([command, data]))

self.cs(1)

def init(self):

for command, data in (

(_SHUTDOWN, 0),

(_DISPLAYTEST, 0),

(_SCANLIMIT, 7),

(_DECODEMODE, 0),

(_SHUTDOWN, 1),

self._write(command, data)

def brightness(self, value):

if not 0 <= value <= 15:

raise ValueError("Brightness out of range")

self._write(_INTENSITY, value)

def show(self):

for y in range(8):

self.cs(0)

for m in range(self.num):

self.spi.write(bytearray([_DIGIT0 + y, self.buffer[(y * self.num) + m]]))

self.cs(1)

main.py

copy the below code and Save it in Pico.

import max7219
from machine import Pin, SPI
from time import sleep

class matrix():
    def __init__(self):
        self.MAX7219_NUM = 4
        self.MAX7219_INVERT = False
        self.MAX7219_SCROLL_DELAY = 0.03
        cs_pin = 5

        spi = SPI(0)
        self.display = max7219.Matrix8x8(spi=spi, cs=Pin(cs_pin), num=self.MAX7219_NUM)
        self.display.brightness(2)
    
    def text_scroll(self, text, scroll_delay=None):
        if scroll_delay != None:
            self.MAX7219_SCROLL_DELAY = scroll_delay
        
        p = self.MAX7219_NUM * 8
        for p in range(self.MAX7219_NUM * 8, len(text) * -8 - 1, -1):
            self.display.fill(self.MAX7219_INVERT)
            self.display.text(text, p, 1, not self.MAX7219_INVERT)
            self.display.show()
            sleep(self.MAX7219_SCROLL_DELAY)

led = matrix()
text = "ABC"
led.text_scroll(text)

import max7219

from machine import Pin, SPI

from time import sleep

class matrix():

def __init__(self):

self.MAX7219_NUM = 4

self.MAX7219_INVERT = False

self.MAX7219_SCROLL_DELAY = 0.03

cs_pin = 5

spi = SPI(0)

self.display = max7219.Matrix8x8(spi=spi, cs=Pin(cs_pin), num=self.MAX7219_NUM)

self.display.brightness(2)

def text_scroll(self, text, scroll_delay=None):

if scroll_delay != None:

self.MAX7219_SCROLL_DELAY = scroll_delay

p = self.MAX7219_NUM * 8

for p in range(self.MAX7219_NUM * 8, len(text) * -8 - 1, -1):

self.display.fill(self.MAX7219_INVERT)

self.display.text(text, p, 1, not self.MAX7219_INVERT)

self.display.show()

sleep(self.MAX7219_SCROLL_DELAY)

led = matrix()

text = "ABC"

led.text_scroll(text)

Conclusion

In ending, the 8×8 LED matrix MAX7219 with raspberry pi pico is a perfect project for anyone interested in electronics and coding. This project is simple With a little bit of creativity, you can create a unique display that is sure to impress your friends.