Ok maybe i''m going about this all wrong but here's my issue.
I have a 12 button keypad where the outputs are in an array. I'm trying to sense each individual button by hooking up a series of resistors and reading the voltage on an analog in (pic18f4550). The problem i'm running into is that the +5v varies and this affects the final out voltage.
is there a way to sense the input voltage with out using another analog pin? i'm using all the remaining pins for data logging.
any help or insight would be greatly appreciated.
thanks
I have a 12 button keypad where the outputs are in an array. I'm trying to sense each individual button by hooking up a series of resistors and reading the voltage on an analog in (pic18f4550). The problem i'm running into is that the +5v varies and this affects the final out voltage.
is there a way to sense the input voltage with out using another analog pin? i'm using all the remaining pins for data logging.
any help or insight would be greatly appreciated.
thanks