Raspberry Pi Pico W LED Matrix
Found a LED Matrix with a Max7219 in my parts bin (box of random electronics in the garage) so looked into getting it working with the Pico and MicroPython.
This is an example why I love open source. The original library I found was functional but sparse, last committed to 4 years ago. There were a few forks, most not much activity. One had been active recently and had some major improvements in functionality so switched over to that fork. https://github.com/enchant97/micropython-max7219
This is the LED Matrix test code I wrote led_matrix.py you have to upload the max7219 library to your Pico first.
It is wired up like;
These are the results,
I did find this useful resource to generate custom characters which could be displayed as a glyph in the fork of the library.