Pololu Jrk USB - Manual (Page 19)

the maximum and minimum possible values of the output; these will be converted to scaled feedback values of 4095
and 0, respectively. If the feedback leaves the range specified by the Absolute Max and Absolute Min parameters, a
Feedback disconnect error will occur. For convenience, the Invert feedback direction option is provided. Select this
option if the direction of motion that you would like to call positive actually results in a decreasing feedback value.
Clicking the button labeled “Learn…” allows scaling values to be determined automatically: with the motor off,
the program will request that the output be moved to its minimum and maximum, and the resulting values will be
recorded.
Input analog to digital conversion
In analog mode, the analog to digital conversion panel lets you specify the number of analog samples to average
together each PID cycle, which determines the precision and speed of the analog to digital conversions. The indicator
labeled “PID period exceeded” at the top of the window is provided as a warning for when the analog sampling takes
more time than the specified PID period.
Selecting the Detect disconnect with AUX option activates an extra feature that allows the jrk to detect if the FB pin
becomes disconnected from the analog voltage input device or shorted to 5 V. This option is intended for use in analog
voltage feedback mode with a potentiometer connected between AUX and ground. When the option is selected, the
jrk will periodically drive the AUX pin low, verifying that this results in a 0 V signal at FB. If the line does not
respond as expected the Feedback disconnect error will occur.
3.d. PID Options
The PID tab of the Jrk Configuration Utility
The PID tab of the jrk configuration utility controls the central calculation performed by the jrk:
Pololu Jrk USB Motor Controller User's Guide © 2001–2014 Pololu Corporation
3. Configuring the Motor Controller Page 19 of 45