Quote:
|
Originally Posted by Mike Bortfeldt
Don,
One thing you may want to try is to use a 1k or 2k potentiometer for your position measurement rather than the 100k. From Section 19.1 A/D Acquisition Requirements - of the PIC datasheet: "The maximum recommended impedance for analog sources is 2.5 k ohms." When we've used higher resistance potentiometers, we've seen a noticeable lag in the A/D value from the actual position. However, other than the slight time delay in acquiring an accurate position measurement, I've used inexpensive Radio Shack pots as well as some Bourns precision potentiometers with good results. (Note that this is only for the RC, not the OI where 100k pots are required.)
Mike
|
Mike,
Thanks for the comments. I can see how a high impedance (100k) would contribute to noise, and we also noticed some lag buy (incorrectly, it seems) assumed it was related to the controller. As well as some better pots, I will also try some smaller ones and see what happens. I believe this may be the key to success, and for that I thank you.
Regarding the OI, the limiting factor there is the current the port can supply, and I agree, 100k is a great choice, but have heard of success with slightly lower values. I don't need to try that, however, because our controller works great with the cheap 100k pots.
Don