Debounced Pushbuttons

This PCB debounces four pushbuttons using a passive low-pass RC filter and Schmitt-trigger inverter. Each pushbutton outputs an active-HIGH signal. There are four pushbuttons on the board.

R = 1~\textrm{k}\Omega, C = 10~\mu\textrm{F}, \tau = 0.01~\textrm{s}

Pinout

Hardware

This PCB uses a 220 ohm pull-up resistor, pushbutton, and low-pass RC filter (1 kohm resistor and 10 ufarad capacitor: tau = 0.01 seconds) to debounce the pushbutton. The output of the low-pass filter is connected to the 7414 Schmitt-trigger inverter to generate an active-HIGH pushbutton output.

Schematic

This schematic shows how each of the four pushbuttons is wired on the board.

Schematic of a single debounced pushbutton. An active-LOW SPST switch is connected via a 220 ohm pull-up resistor. The output of the switch connects to an RC low-pass filter with 1k resistor and 10u capacitor to the input of a Schmitt inverter. The inverter's output represents the active-HIGH debounced signal.