Was Chopper circuit - Now ver 3.2, G298

>
> No question, I quite often use an R-2R resistor divider instead of
> buying a "real" DAC.
>

In this application, a guy doesn't even need an R2R. By carefully
picking the resistor values for use in a simple divider, all that's
needed for an 1/8 step controller is 8 resistors per axis. A little
less real estate, a little less cost and perhaps most importantly, fewer
uC pins.

The values are not unusual .. a stack of 5% resistors, and a good meter
to measure them with, will easily yield the exact values required to
within 1% of the "correct" reference voltage.

And if a guy was REALLY tight on uC pins and was willing to devote a bit
more PCB real estate to the problem, both channels could be done using only
6 pins.

Alan

--

Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta