Keypad de-bouncing apparatus and method

Details Keypad de-bouncing apparatus and method Keypad de-bouncing apparatus and method

2007-11-14

2010-10-05

Tsai, Henry W. H. (Department: 2184)

Electrical computers and digital data processing systems: input/

Input/output data processing

Peripheral adapting

C341S024000

Reexamination Certificate

active

07809867

ABSTRACT:
An apparatus and method for de-bouncing keypad inputs is disclosed including interrupting a processor upon detecting a key press, reading input signals from the key pad to determine an initial port value and starting a timer. A keypad interrupt is disabled and processing resumes until expiration of the timer. The timer interrupts the processor and the input signals are read a second time and combined with the initial port value to determine a key identifier. The timer is started again and processing resumes. Upon expiration of the timer the processor checks for key release. If release is not detected, the timer is again started. If release occurs, the timer is disabled and the keypad interrupt is enabled.

REFERENCES:
patent: 5760714 (1998-06-01), Zimmerman
patent: 2006/0049965 (2006-03-01), Laliberte et al.
patent: 2007/0159363 (2007-07-01), Suen et al.
patent: 0580347 (1994-01-01), None
Definition of ‘reference voltage’, 1996, Academic Press.

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