If you want to add a keypad to your Arduino project, the options are pretty limited. There’s that red and blue 4×4 membrane we’ve all seen in password-protected door lock projects,… ...

Initially, one end of the push button was connected to pin 13 of the Arduino. However, this caused unreliable button behavior. This is because pin 13 is connected internally to the onboard LED, which ...

Each button is wired to an Arduino input pin configured with INPUT_PULLUP, meaning it reads HIGH when not pressed and LOW when pressed. When a button is pressed (detected as a falling edge), the state ...

To read each button push, the Arduino brings one keypad input line high and checks the voltage of the four output lines in order. The diodes on the PC board prevent feedback across the rows and ...