I mentioned in Raspberry Pi Pico Multi MIDI Router – Revisited that I have several dual-MIDI interfaces for a Raspberry Pi Pico designed by @VE7FIM from Twitter. In that post I built a simple proto-board carrier for the Pico. In this post I have a pcb design for something to do the same. This is definitely going to a post of very limited usefulness to anyone but me, so I’m recording it here as “notes to self” once again.
Update:
- Find the Build Guide here: Raspberry Pi Pico Dual MIDI Carrier – Part 2
Tutorials used in this project:
- Raspberry Pi Pico MIDI Channel Router
- Raspberry Pi Pico Multi MIDI Router – Part 4
- Notes on KiCad for PCB design: Arduino Uno Dual Merge MIDI “Shield” – Part 2
If you are new to microcontrollers, see the Getting Started pages.
The Circuit
The key reason for this design is structural support for the Raspberry Pi Pico when used with the dual-MIDI interfaces, but more on that in a moment.
In terms of the circuit, I want to be able to use the Pico’s two UARTs and eight PIO channels to support the full six MIDI IN/OUT ports enabled by the provided boards. Consequently, this carrier has to provide three sets of headers, one for each of the three dual-MIDI boards I want to use.
Building on the updates to the router, I’m also looking to provide connections for a SSD1306 OLED display and a rotary encoder, but would like each to be an option for either pcb mounting or breaking out onto some kind of front panel should I so desire.
PCB Design
So given all the details mentioned above, this is the design I’ve come up with. The original dual MIDI boards are just over 100mm long, but I decided to limit the pcb design to 100mm to keep it in the “cheap to manufacture” category. A challenge was getting the positioning of the mounting holes just right, especially as the board isn’t quite the same size as the MIDI modules!
Another choice was the width – I wondered about limiting it to fit “just behind” the MIDI sockets, but in the end went for full-width. The idea will be that I’ll use mounting pillars that raise it to the same distance as between multiple boards.
I’ve positioned a set of header pins for the rotary encoder such that if used with a front panel, the encoder can sit to the right of the display. But when used pcb-mounted, the encoder will sit just below the display. The header pins support the very common KY040 rotary encoder module, with five connections.
It will not support the use of the header connections and pcb-mounted encoder at the same time.
Closing Thoughts
As I say, this one will be very specific to me, but I’ve listed it anyway. I have plans for these MIDI interfaces and this will (I hope) allow me to start experimenting properly.
This is the fifth, and final, PCB in this round of manufacturing made possible with some discount vouchers from the Seeed Fusion PCB service.
Kevin
Simple DIY Electronic Music Projects 