will need:
* 2 Arduino Pro Micro's. You can find theses on aliexpress for ≈3.50USD each.
-* 2 TRRS sockets
-* 1 TRRS cable.
+* 2 TRRS sockets and 1 TRRS cable, or 2 TRS sockets and 1 TRS cable
Alternatively, you can use any sort of cable and socket that has at least 3
wires. If you want to use I2C to communicate between halves, you will need a
Wiring
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-The 3 wires of the TRRS cable need to connect GND, VCC, and digital pin 3 (i.e.
+The 3 wires of the TRS/TRRS cable need to connect GND, VCC, and digital pin 3 (i.e.
PD0 on the ATmega32u4) between the two Pro Micros.
Then wire your key matrix to any of the remaining 17 IO pins of the pro micro