I haven't done this yet, but am in the midst of a multimeter type project
just like yours.  I planned to simply setup trigger thresholds such that in
any given range, if the target threshold is exceeded for XXmS, then I switch
ranges.  Let the value settle, then try again.  I strongly suggest that you
look at the ceramic resistor elements available from Caddock.  I used one of
those and an Analog Devices analog mux part.  When I change ranges, I select
a different mux channel and run a different tap from the resistor element to
my ADC.  Wish I could tell you that it works, but I'm not there yet.  The
LCD display and '924 code displays bogus numbers, though!

Chris Eddy

Justin Grimm wrote:

> Hi all
> Im trying to build an autoranging circuit for a digital multimeter,
> I was thinking of a pic controlling a voltage divider circuit, any ideas
> on
> how this can be done?
>
> Thanks
> Justin Grimm