Hi all, I'm quite new at this, so please bare with me. I have a question regarding Atmel AT89C51SND1. For my application I need 12 different keys. As i understadn the AT89C51.. has 4 interrupt driven keys. My guess is I can setup a 4 x 3 matrix keyboard? But, I need help in understanding how I would go about doing this in C. Also, more specifically I need to know, if a user presses a key then how would I know which one of the 12 keys was pressed? Thank you very much for your help.
I have a question, since the keypad is interrupt driven how would i deal with that? Since you have to debounce anyhow, it makes no sense to make the keypad routine interrupt driven by key presses. Make it run every 10ms controlled by a timer. If you insist on interrupt when key pressed, just enable all columns when you are not in the ISR> Erik