Embedded Files
Schematic
Keyboard matrix
Diode arrays (8 independent) used to simplify soldering
Left and Right ESPs
USB 5V to computer (master board)
Split board communication at 3.3V
Power regulation (master board)
Layout
Assembly, Test
UART provides 3.3V but we had to flash the ESP before it could accept UART.
USB provides only 5V, so we had to use an external 9V battery and LDO to jump the 3.3V power to the ESP.
Our switches were the correct footprint but polarized which we didn't expect. We tilted them off at an angle to correct the proper pins.
Results
It types!! Lessons for next time:
tailor the board to hand sizes of users. This keyboard is a little wide for Toby.
Include LDO on second board for easy flashing.
Check parts of unexpected features (polarity)
Consider what side of the board will be down. We had to lift the board due to the USB-C socket facing the table.
Use a larger LDO than probably necessary. to prevent overheating and allow more stable power.
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