David J Binnington wrote:

> As I am already going to need I2C I thought about using it for the keys but
> I am not sure of the best way i.e. No parts and cheap!  I am likely to have
> at least 2 PCF8574 hanging on the I2C bus together with 2 other micros in
> the system.  I suppose I could add something like a 16F628 just to do the
> key scanning.  Any thoughts?

If you are going to add another PIC, then I would rather do the encoders
on that PIC as scanning the encoders is timing critical, so the PIC then
runs free to do it's own thing (and also freeing up the master a bit
more, code and pin wise). This PIC then sends the three count values to
the master PIC when asked.

Other than that, go tell whoever suggested the rotary approach to go fly
a kite.

:)
Quentin

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