Shared Projects by jepler

This PCB accompanies the Adafruit Learning System guide Desk Calculator with CircuitPython. See the guide for more details, including BOM, software, & 3D printed parts. It is designed to work with Adafruit Feather microcontrollers and 20 MX-footprint keyswitches.

Hook your Feather STM32F405 to a Protomatter RGB Matrix with a minimum of fuss. The RGB and CLK pins are configured for a minimum of memory usage. Just follow the silkscreen to get the proper RGBMatrix setup.

Note that the pinout is different than the one on the Learn guide, I (unintentionally) swapped OE and LAT.

Pinout: matrix = rgbmatrix.RGBMatrix( width=64, bit_depth=4, rgb_pins=[board.D13, board.D12, board.D11, board.A4, board.A5, board.D6], addr_pins=[board.A0, board.A1, board.A2, board.A3], clock_pin=board.D5, latch_pin=board.D10, output_enable_pin=board.D9)

Clock generator in a box, with CLKIN for a reference clock and a Trinket for runtime configuration

There is a problem with the 3v power rail on the board. To work around it, either * apply the clock in signal only after power on * cut the 3v power trace, jumper to GPIO1, and use GPIO1 to “sequence” the power on

Based on Adafruit’s brekaout for the si5351: https://learn.adafruit.com/adafruit-si5351-clock-generator-breakout/overview

Resistors: 1k 0805 Caps: 2 x .47uF, 1x10uF 0805 SI5351 Trinket M0

(Untested) FeatherWing to Commodore User Port adapter, with screw terminals

Converts SPI from Raspberry Pi-syle 40-pin connector to Mesa 7i90 26-pin connector.

You can use three 88-ohm 0805 surface mount resistors for series termination, or put big solder blobs over the pairs of resistor pads.

You have your choice of soldering male pin headers to the top, or (less common) female sockets to the bottom. Shrouded male headers, together with ribbon cables, are recommended. (sadly, the footprints do not show the correct notch position for polarized shrouded connectors)

Not a level converter, your Pi board must have Mesa-compatible voltages. (in general, the Mesa 7i90 is compatible with 3.3v and 5v on its SPI pins)

I have personally tested this with Pi3 and ODroid XU4.