Neotrellis Grid Code for Adafruit M0 and M4 controllers.
This code should work with any of the various Adafruit SAMD21/51 M0/M4 controllers such as Feather, ItsyBitsy, etc.
NOTE - You will need to recompile the code for the specific board you are using. Compiled firmwares such as neotrellis_m4_8x8_featherM4.UF2 will ONLY work on that specific board type.
Step 1: Be sure update to the most recent TinyUSB library version. If you're using Arduino, it's best to use Manage Libraries in Arduino to install/update TinyUSB.
Step 2: Be sure you check the board addresses for your build and adjust the code as needed if you do something different than the default described here.
Adafruit 8x8 NeoTrellis Feather M4 Kit Pack
If you have this (or have built an 8x8 grid with Feather M4) you can use the enclosed compiled firmware neotrellis_m4_8x8_featherM4.UF2 assuming your setup uses the following addresses
{ Adafruit_NeoTrellis(0x2E), Adafruit_NeoTrellis(0x30) },
{ Adafruit_NeoTrellis(0x32), Adafruit_NeoTrellis(0x36) }