another way to get a keyboard matrix to work off 1 adc pin

[wdmagic]

Personally i like to use the 74C922N IC's for interfacing keypads, it uses 1 interupt and 4 data lines for a binary input, there are normally 3 basic ways of handling keypads (there are more but they are more rare)
1.ADC Keypad IO (uses only 1 pin, Slower, More code space, must set up polling)
2.Serial Keypad (uses 1-3 pins based on IO type, fast, still need to set up polling) possible to add extra pin for firing a Interupt
Article on making a serial keypad You will have to modify this code, or look on internet on making serial keypads
3.Genuine keypad IO (5 pins, Interupt based - instant results, no polling needed)
Article where I got mine working

[tasmod]

That would be a handy way to do a keypad for radio use.

I have a project in build at the moment which strobes the keypad lines, unfortunately this generates interference in the receiver.
Using decoupler caps prevents the strobe. Using ferrite bead chokes reduces the output of each line.

I'm using a 4x3 keypad as it suits my needs.

With precision resistors this could be a good way to do it once the ADC values have beeen determined for each keypress.

Rob