> that subject isn't very informative!  My problem is that I'm using the
> PWM output to control the rate of charge of some batteries and I'm
> monitoring the current into the batteries by measuring the voltage
> across a 1/2 Ohm resistor is series with the batts, the problem is the
> PWM output is controlling the current by high speed switching and is
> interfering greatly with the numbers on the A2D input, I've tried
> basically filtering it out using diodes and caps but it doesn't work
> well and I have to use a long median average routine from many samples
> to get half decent numbers for the current flow.

Don't try to smooth the voltage on the resistor, filter it after it's gone
thru a buffer or something.  Since you want the average, the right low
pass filter should work fine.  Additional filtering in software is still a
good idea anyway, but you have to get rid of the high frequencies
externally.


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