Decoding rotary switches

[timmers]

.... or use a parallel in serial out shift register. By cascading several registers you can have as many inputs/outputs as you like.

Tim.

[AndrewC]

Steve:

Figure 3 illustrates a resistor network, which changes a
4x4 keypad into a switchable resistor matrix. The
resulting resistance is read by an ADC or a capacitor
charge timer, which determines the key that is pressed.
This is practical only when one key is pressed at a time.

... so that doesn't really work in this case, but those are good links from Microchip, thanks

Al: I think the usual solution is to use diodes like you say.

Tim: I'll have to think about that

Thanks for the inputs

Andrew

[mister_e]

So I haven't explain it correctly then... and i wasn't refer to a 4x4 matrix directly but multiple switch with a single I/O and a single (or multiple) ADC channel. Food for thoughts

[AndrewC]

Actually this is really one of those situations where I'm trying to force a solution to a problem - I picked up a bag of these switches for a couple of dollars and now I'm looking for a use. The application is just to provide a knob to control the duty cycle of three different PWM module. The easiest solution is just using a pot and an ADC channel - three pins, some case commands and it's done.

Sometimes one's head gets lost in a dark place !

Andrew