MicroPython Max7219 8x8 LED Matrix

A MicroPython library for the MAX7219 8x8 LED matrix driver using the SPI interface. Supporting custom fonts and cascading matrices.

Features

• Cascading matrices together
• Custom font support
• Extends the FrameBuffer class
• Removes the need to specify offset for text method
• Extendable

Examples

Raspberry Pi Pico

from machine import Pin, SPI
from max7219 import Matrix8x8

spi = SPI(0, baudrate=10000000, polarity=1, phase=0, sck=Pin(2), mosi=Pin(3))
ss = Pin(5, Pin.OUT)

display = Matrix8x8(spi, ss, 4)

# change brightness 1-15
display.brightness(5)

# clear display
display.zero()
display.show()

# show text using FrameBuffer's font
display.text("CODE")
display.show()

Docs

• For any change to the FrameBuffer to appear, call the .show() method
• You may have to add delays when calling methods, these are documented in the datasheet
• Tested on 1.19.1

Display Text

display = Matrix8x8(...)

display.zero()
display.text("HI!")
display.show()

Custom Fonts

Custom fonts (glyphs) can be provided, each glyph must be 8x8. Missing characters will use default characters from FrameBuffer.

GLYPHS = {
    "X": [
        [0, 0, 0, 0, 0, 0, 0, 0],
        [0, 1, 0, 0, 0, 0, 1, 0],
        [0, 0, 1, 0, 0, 1, 0, 0],
        [0, 0, 0, 1, 1, 0, 0, 0],
        [0, 0, 0, 1, 1, 0, 0, 0],
        [0, 0, 1, 0, 0, 1, 0, 0],
        [0, 1, 0, 0, 0, 0, 1, 0],
        [0, 0, 0, 0, 0, 0, 0, 0],
    ],
}

display = Matrix8x8(...)
display.text_from_glyph("X", GLYPHS)

Shutdown / Wake

Shutting down and waking up the display is supported. This should allow a device to consume just 150μA when it's not needed. When the display is woken from shutdown the previous display should appear.

# shutdown display
display.shutdown()

# wake from shutdown
display.wake()

Test Mode

Test mode will enable all pixels, shutdown mode has no effect when testing mode is enabled.

# enable test mode
display.test()
# disable test mode
display.test(False)

Extending

Scrolling Text

Although not built-in you could add scrolling text like shown in the following example:

from utime import sleep_ms

from max7219 import Matrix8x8

class Matrix8x8Ext(Matrix8x8):
    def scroll_text(self, s, ms_delay=100):
        s_width = len(s) * 8
        n_pixels = self.num * 8
        while True:
            for x in range(n_pixels, -s_width, -1):
                self.zero()
                self.text(s, x)
                self.show()
                sleep_ms(ms_delay)
        return s_width

Attribution

• Original code by @mcauser
• Data-Sheet

License

Licensed under the MIT License, found in LICENSE.txt.