Muncy, Geissler, Olds & Lowe, P.C.
Key press detecting circuit and method for detecting the status of multiple keys through a single pin
A key press detecting circuit and method detect the status of multiple keys through a single pin. In an embodiment, a constant current is provided to apply to a key module through a single pin, to generate a voltage at the single pin that is related to the equivalent resistance of the key module observed from the single pin, and the voltage of the single pin is compared with a set of reference values to identify the status of the plurality of keys. In another embodiment, a variable current is provided to apply to a key module through a single pin in such a way that the variable current is adjusted to maintain a constant voltage at the single pin, and the variable current is compared with a set of reference values to identify the status of the plurality of keys.
Pixart Imaging Inc.
H H
H01H H03K
inventional inventional
Yung-Hung
Chen