> The problem here as you note is the 8 bit AD, which isn't enough for my
>application.

If you have time during operation, you can increase the significant bits by
multiple samples, with a known noise factor added in.  256 samples will
yield 12 bits resolution easily.

                 R1
PORTx.y -----/\/\/\/\--o---Analog signal
                       |
PORTA.b ---------------o
                       |
                       -
                       -C1
                       |
                      GND

By toggling PORTx.y pin high/low every n samples (I used 16 in my project)
and selecting the right values for R1 and C1 (C1 may not be necessary), it
works.

Somebody else can explain how/why - I'm busy!  Wagner would be a good
candidate...

Andy

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