Has anyone done this before?
If it was a 10 turn precision pot, that was linear throughout it's range, I'm wondering if that would make a variable electronically controlled potentiometer with 512000 positions using the microstepper CWD860?
So, because the poteniometer is electronically controlled, the position would be known and could be converted to logic inputs of 7 segment readout.
A quick check on digikey shows their "best" digital pot have only about 1000 positions, and you would have to deal with the coding with a uC.
I'm guessing that the number of digits would be 5 1/2 ? (512000/10/10/10/10/10/5)
Edit: So, if a 10V reference was used, it would be about 51200 steps per volt, the output would need to be calculated for the correct voltage.
If the micro-stepper controller had more positions than the digit readout could be increased if this is correct.
So a 5 1/2 digit read out of a compared voltage to a known reference would give a pretty accurate DC voltage measurement which is the goal here...This would involve 6x 74192 up/down counters, 2 OR gates and an inverter, so that the up/down can be switched, and a clock for the counters (any VCO or 555 type will do) would also be be the stepping clock.
If the ref was 10V and the input was lets say 50V, then the input voltage would of course have to be divided down before the "measurement" but this could be done with relatively cheap precision fixed resistors.
If the ref was 10V and the measured signal was divided down to 5V, the stepper would start the "measurement" by turning the pot connected to 10Vref and 0V while the wiper output is used with a comparitor against the 5V signal. So the microstepping would give 512000 position, and can be precisely controlled. When the comparitor goes high, then the stepper changes directions. This starts the pot to go in the opposite direction, and when the comparitor goes low, the stepper changes direction, and this happens over and over again while centering on the position that has equaled the input voltage.
6 linked up down counters would be counting the whole time and now bouncing between a range of voltage points that the motor is controlling. The BCD counters could directly output to my 7 segment output displays (I've got alot of TIL311 which have a 4 bit latch, decoder and driver built in them).
Do you think the 10 turn precision pot would be linear?
Is it really 5 1/2 digits?
If the pot was calibrated, with regression test points to verify the resistance points the output could be adjusted by having stop points on the pot.
Well, what do you guys think?
EDITED: due to fast typing and poor grammar.