that was exactly how my h/w engineer designed the circuit and it is just wonderful. The only alteration I see is instead of 18k, he used 4k7 and the value of the capacitor is 0.1µF.

Sriharsha,

have you read my last reply? I have spent much time and energy to write it and would have been happy about some reaction from you.

Anyway, if you would have read it, you would know now, that 4k7 resistor in combination with 100nF capacitor yields a much, much, much to little value of T, namely only 0.2msec. I don't know about any key having a bounce duration of less than 0.2msec. So, circuit consisting of 4k7 resistor and 100nF capacitor is totally unsuited for debouncing purpose!!

Kai