Waveshare Zero MIDI Proto PCB Build Guide

By Kevin on March 14, 2025

Here are the build notes for my Waveshare Zero MIDI Proto PCB Design.

Warning! I strongly recommend using old or second hand equipment for your experiments. I am not responsible for any damage to expensive instruments!

Bill of Materials

Waveshare Zero MIDI Proto PCB (GitHub link below)
1x H11L1 optoisolator
1x 1N4148 or 1N914 signal diode
1x 10Ω, 1x 33Ω, 1×220Ω, 1×470Ω resistors
1x 100nF ceramic capacitor
2x 5-pin MIDI DIN sockets OR 2x TRS MIDI sockets
Optional: 1x 6-way DIP socket
Optional: 2x 9-way pin header sockets

Power supply

1x 7805 regulator (optional)
1x 100nF ceramic capacitor
2x 47uF electrolytic capacitors
1x 2.1mm barrel jack
1x SPST 3-pin, 2.54mm pitch, switch
2-way pin header

Build Steps

Taking a typical "low to high" soldering approach, this is the suggested order of assembly:

All resistors and diode.
DIP socket (if used) and TRS sockets (if used).
Disc capacitors.
Power switch.
2-way pin header.
9-way pin socket headers.
Electrolytic capacitors.
Barrel jack.
DIN sockets (if used).

Here are some build photos.

V1 Errata

Note: the first version of the board (in fact the one used in the above photos) has two errors:

The footprint of the TRS socket doesn't quite line up properly with the MIDI DIN socket. The TRS sockets can still be used, but the outer plastic alignment pins need to be removed as they don't align with the holes, as shown below.

The more serious error in the first version though is that the spacing of the headers for the Waveshare Zero is 2.54mm too wide.

Curiously, they do fit the board used in my ESP32C3 OLED Mini MIDI Montor, but RX/TX are not in the right place for this board.

If tall headers (he usual, cheaper ones) are used then they can be slightly bent enough to get a board fitted, but this isn't ideal.

Both of these issues have been fixed in the version stored on GitHub.

Testing

I recommend performing the general tests described here: PCBs.

PCB Errata

As already mentioned, there were some issues with V1 of the PCB, but at the time of writing there are no further issues with the version on GitHub.

Enhancements:

None.

Find it on GitHub here.

In Use

The board can be powered in one of four ways:

Using the USB-C connection of the Waveshare Zero.
Using 7-12V input via the barrel jack.
Using 5V directly via the 2-way pin header.
Using 5V input via the barrel jack provided: the regulator is not populated and the bypass solder bridge is connected.

The two rows of pins from the Waveshare Zero are duplicated and broken out to headers near the prototyping area as shown below. There are also rows of 5V, 3V3, and two rows of GND.