Using two scope probes to simulate a diff probe can work as described, done it many a time. :-)
Problem is ground effects- if they common ground does not cause a problem and the light phase and offset differences aren't critical, then sure, this is a good alternative. But if ground references or other probe differentials could affect your results (especially when trying to find noise) a diff probe can make all the difference (pun intended). :-) On Tue, Mar 10, 2015 at 3:17 PM, Jim Larson <[email protected]> wrote: > Thanks for looking at this Nathan! You have the correct driver board. > > However, the "A0" thru "A5" on the schematic refers to the pins that set > the I2C Address for the board, not to Analog pins on the Arduino. Just a > bit confusing! The only connection to Arduino (besides power and ground) is > the I2C bus on SCA and SCL. (It is also possible to drive two servos, but > I'm not doing that.) > > > > On 3/10/2015 2:15 PM, Nathan McCorkle wrote: > >> On Mon, Mar 9, 2015 at 1:24 PM, Jim Larson <[email protected]> wrote: >> >>> Following is a description of a problem I'm having in a motor control >>> system >>> I'm working on down here in Sunny San Diego. Any thoughts or insights >>> would >>> be most appreciated. >>> >>> I have 8, 10K linear pots. The wiper of each pot is tied to an analog >>> input >>> of an Arduino Mega (Analog pins 0 to 7). >>> >> Hmm, I think I'm looking at the correct motor shield schematic here: >> https://learn.adafruit.com/assets/9536 >> >> If so, it seems that has 5 of the analog pins tied up... even if they >> aren't being used on the motor shield in your setup (I can't tell on >> cursory glance) maybe they aren't turned off (if they can even be >> disabled). >> >> If I'm right and that is the correct schematic... you could either >> destructively cut the traces coming from the analog pins, or get some >> headers between the Mega and the motor shield stack, and for the >> analog pins instead of upright headers, use 90-degree angle headers so >> the analog are completely diverted from the motor shields. >> _______________________________________________ >> dorkbotpdx-blabber mailing list >> [email protected] >> http://music.columbia.edu/mailman/listinfo/dorkbotpdx-blabber >> >> >> >> ----- >> No virus found in this message. >> Checked by AVG - www.avg.com >> Version: 2012.0.2250 / Virus Database: 4257/8766 - Release Date: 03/10/15 >> >> >> >> ----- >> No virus found in this message. >> Checked by AVG - www.avg.com >> Version: 2012.0.2250 / Virus Database: 4257/8766 - Release Date: 03/10/15 >> >> >> > > --- > This email has been checked for viruses by Avast antivirus software. > http://www.avast.com > > _______________________________________________ > dorkbotpdx-blabber mailing list > [email protected] > http://music.columbia.edu/mailman/listinfo/dorkbotpdx-blabber >
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