debouncing

Debouncing is a technique used to ensure that only a single action is taken in response to a noisy or rapidly repeated signal. It is commonly applied to input devices whose signals can generate multiple transitions when they should be treated as one, such as mechanical switches, keyboards, mouse buttons, and sensors. When a signal changes state, contact bounce or electrical noise can cause several rapid transitions before the signal settles. Debouncing filters these glitches by delaying response until the signal has remained stable for a defined interval.

Software debouncing typically uses a timer: on the first detected edge, a delay is started; if another edge arrives before the delay expires, the timer is reset. When the delay expires without a new edge, the action is executed. Some implementations trigger on the first edge (leading edge) and then ignore subsequent edges within the interval. Hardware debouncing uses passive components such as resistors and capacitors (an RC network) or Schmitt triggers to smooth transitions before the signal reaches the processor.

Common delay values depend on hardware: keyboard or mechanical switches may use 5–20 milliseconds, while other sensors may require tens of milliseconds. Debouncing is widely used in user interfaces, embedded systems, and data acquisition to prevent duplicate events and spurious readings.

Limitations include added input latency and potential masking of legitimate rapid events. In some cases, throttling or filtering approaches are preferred, or debouncing is combined with edge-detection strategies. The concept contrasts with throttling, which restricts processing rate rather than collapsing rapid sequences into one event.