https://nalar.dev/tags/firmware/ Recent content in Firmware on Nalar Hugo en-us Sun, 13 Sep 2026 00:00:00 +0700 https://nalar.dev/keyboard-debounce-filters-contact-bounce/ Sun, 13 Sep 2026 00:00:00 +0700 https://nalar.dev/keyboard-debounce-filters-contact-bounce/ <p>A single physical key press does not always create one perfectly clean electrical transition. In many mechanical switches, metal contacts meet and settle over a short interval. During that interval, the electrical state can change several times before becoming stable.</p> <p>Keyboard electronics have to separate that brief contact behavior from deliberate repeated presses. The filtering process is commonly called debounce.</p> <h2 id="a-switch-can-change-state-several-times-while-settling">A switch can change state several times while settling</h2> <p>A basic mechanical key switch acts as an electrical contact. Pressing the key moves parts of the switch until conductive surfaces meet. Releasing it separates those surfaces again.</p>