Hi all. I am trying to build a keypad using the AD converter on a ATMega48. I've been doing some research on google and found out that is best achieved using a resistor matrix.
I also found an example of such a matrix and some code examples to help me on my way. I think I understand how it all works, but I am struggling with a very basic question. Why these values?
I can understand that you have different resistance on each key, and that leads to different voltages to be read by the ADC. But why should it be 3K3 ohm and not 3k, why 15K and not 10K. Is there a reason for this, are there best practices for this? Is there a formula or proccess for creating these?