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Version 2 is easy to build with simple tools, because there are no SMD parts.
Please find a shared list on DigiKey with the exact parts the design was tested with DigiKey might not be the cheapest supplier and not much time was spend search for the cheapest possible parts.
The design is very modular, you can just build the MIDI part of the pedal or just the audio part. In addition, the power supply is also optional. The parts on the shared DigiKey list are tagged with the module (MIDI,AUDIO,PSU) to filter the list.
Since the Power Supply uses a fully isolated DC-DC converter (which is pretty expensive). The DC-DC converter supports a wide range of input voltages between 9 and 36V.
Using cheap USB power supplies can be problematic, they might introduce some noise to the audio signal path, which we want to avoid. With the power supply on the PCB you can get most of the audio quality of the HiFi Berry DAC/ADC+.
IMPORTANT: The system can also be powered from a USB power supply. Be careful not to use both together. When you want to connect the USB port, the Jumper J14 must be removed! Otherwise it might damage either of the power supplies or your computer! Please be careful!
In addition to the parts mentioned on the shared DigiKey list you will need:
- Raspberry Pi Compute Module 4
- Waveshare CM4 Nano A
- HiFiBerry DAC+ ADC PRO
You have to decide for a variant for MIDI connectivity:
- On-board DIN-5 connectors J1, J2
- On-board 3.5mm jack connectors J16, J17
- Off-board midi plugs of your choice wired to J15
The build is pretty simple, since the design is using only through hole parts (by intention no SMD parts).
The only tricky parts to solder are the RGB LEDs, because their footprint is pretty dense. Be careful not to apply too much solder to avoid bridges between the pins
The other (a bit unconventional) design is the USB connection between the Pico and the CM4 carrier board:
- On the Pico side spring loaded pins are connecting to the test contact pads on the bottom side of the Pico board
- On the CM4 carrier board soldering a USB plug to standard pin headers.
I have also desoldered the additional connectors on the HiFi Berry Board to save some space. This however voids the guarantee of the HiFi berry board.