> >I wondered if it was possible to create a DAC with just 1 ADC pin.
> >The reason is that I have just a few pins and pwm is too slow.
>
> Robert Rolf suggested a method to me many, many years ago: 100R from pin
to
> 1u0 cap +.  Other side of cap is Gnd.  Output voltage comes from cap
> +.  This is a high impedance output - buffer as required.
>
> Read the voltage on the pin and compare to the desired value, then set the
> pin as output (either HI or LO, as required) for a very short period to
> 'nudge' the voltage in right direction.  The voltage on the cap will track
> the desired value.

How utterly obvious.
How utterly brilliant !!!
The ATtiny26 that I happen to be using, which has zillions of A2D inputs,
suddenly acquires new capabilities.
Some playing with time constants would be needed to optimise results.
Now we need an 8 channel analog buffer :-)


        Russell McMahon

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