i have two interrupt service routines and i am sure they both work as i've test them individually along with the main program.
However when i want to implement both of them together, my atmega48 doesn't even response to any of my button pushes.
the interrupt service routines are for the USART and the debouncing algorithm by the "Debouncing Bible" by Jack G.Ganssle.
I used a timer overflow to implement the ISR for my debounccing algo.
Is it possible that one of the ISR is causing the problem ? but i suspect it might be the timer overflow used in the debouncing algo might be probing my input buttons too often.
Please advise .. Thanks !!