Patent ID: 8884791

Claim:
A keyscan apparatus comprising: a keyscan controller coupled to receive a periodic signal that is provided to a communications device to establish operation of the communications device, the keyscan controller having an output to provide a scan signal to couple to a keypad interface device to cause a keypad to be scanned; a counter having a first output and a second output; a keypad activation logic; wherein in the absence of the periodic signal, the counter operates in response to the output of the keypad activation logic to provide a signal at the counter first output that causes the keyscan controller to provide the scan signal; wherein in the absence of the periodic signal, the counter operates to provide a signal at the second counter output that causes the output of the keypad interface device to assume a predetermined condition; and wherein the keyscan controller is operative to interrupt a system processor if in the course of a debounce procedure subsequent to the provision of the scan signal, and in response a key is determined to be activated.