Arduino + 4 x 4051 Multiplexer + 28 POTS = MIDI controller
Pretty straightforward build. 4 multiplexer output pins into the Analog in ports of the Arduino 1,2,3 and 4.
Pitfalls: If you have an Arduino Leonardo: use Serial1.print to write to the TX on the 2nd pin for MIDI. The normal Serial.print writes to the USB TX. (very useful for debugging)
Pitfalls: I have a significant voltage drop therefore I use the first pin on the first multiplexer to read the analog value and use it as a reference when mapping.
ex: midi_value = map(analogValue, 0, myREF, 0, 127);
myRef is read in the setup() function from 4051 chip 0, address 0.
1. Placeholder graphics and placement (Arrangement is identical to MiniMOOG 😉 )
2. Drilled holes and final placement
3. Bottom view with first ribbon cable in place
4. Remaining ribbon cables and +5V / GND connections made
5. Perfboard with BUS and sockets for the multiplexers
6. Wired together + added the MIDI connector
7. Close-up of the wiring
8. Finished product, running NI Massive
10. Close-up of finished product
And the final “product”. 🙂