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Explore Stack Internalyou can use a so called multiplexershift register. One very common one is a 74HC165 shift register (https://playground.arduino.cc/Code/ShiftRegSN74HC165N/).
With one of such IC you can connect 8 buttons, however you can daisy chain max 4 to get 4 * 8 = 32 button inputs, only using 4 digital pins of the Arduino. In your case you would need 3 ICs to get 24 (thus 20) button inputs.
you can use a so called multiplexer. One very common one is a 74HC165 shift register (https://playground.arduino.cc/Code/ShiftRegSN74HC165N/).
With one of such IC you can connect 8 buttons, however you can daisy chain max 4 to get 4 * 8 = 32 button inputs, only using 4 digital pins of the Arduino. In your case you would need 3 ICs to get 24 (thus 20) button inputs.
you can use a so called shift register. One very common one is a 74HC165 shift register (https://playground.arduino.cc/Code/ShiftRegSN74HC165N/).
With one of such IC you can connect 8 buttons, however you can daisy chain max 4 to get 4 * 8 = 32 button inputs, only using 4 digital pins of the Arduino. In your case you would need 3 ICs to get 24 (thus 20) button inputs.
you can use a so called multiplexer. One very common one is a 74HC165 shift register (https://playground.arduino.cc/Code/ShiftRegSN74HC165N/).
With one of such IC you can connect 8 buttons, however you can daisy chain max 4 to get 4 * 8 = 32 button inputs, only using 4 digital pins of the Arduino. In your case you would need 3 ICs to get 24 (thus 20) button inputs.
