A simple board to convert matrix keypad with 8 pins to use only one ADC pin and VCC-GND.
I built the circuit on a prefboard. Works nicely. Keys in bottom row don't work. All print 'D' when pressed. Need to see what's wrong.
Still using old resistor values. Ill change resistors when order reaches me. Photos of build posted. Other side of board will be posted when it arrives on my OneDrive.
Tested with 5.1K row resistor and 1K column resistor
keys 1 to 9 work. As we move to down right corner, the stability decreases. May need to tweak resistor values.