Resistance based keyboard key discrimination

摘要: In place of a conventional n×m sense line/drive line matrix for keyboard key detection, discrimination between keys is carried out with one or more current divider voltage circuits, the result that number necessary IC pin connections may be reduced. The switches are arranged into circuits. embodiment, each circuit in parallel other at respective points along resistive switch extending from Vcc to ground. When closed by depression, provide shortened paths ground, thus resulting division effect. A input an A/D converter micro-controller which performs discrimination. within (1) ground; and (2) micro-controller. closed, senses switch. sensed varies relation has been depressed, as division, thereby allowing out.