Pololu Jrk USB - Manual (Page 41)

5. Setting Up Your System
The following step-by-step procedure is recommended for configuring a feedback system for use with a jrk motor
controller.
Connecting power and feedback
1. Connect your jrk to a PC with a USB cable and launch the configuration utility. The red LED should be on.
2. Select the “Reset to default settings…” option from the File menu to load a safe set of settings.
3. With your power supply off, make the power connections to VIN and GND.
4. Connect your feedback sensor to the FB input. If you are using a potentiometer as a feedback sensor, use the
AUX pin to power it, and enable Detect disconnect with AUX in the Feedback tab.
5. Set the “No power”, “Motor driver error”, “Feedback disconnect”, and “Max. current exceeded” errors on
the Error tab to Enabled and latched. This should stop your system in case of any major problem.
6. Click “Apply settings to device”.
7. Turn on power.
8. On the Error tab, click “Clear Errors” to remove the errors caused by turning off the power.
The red LED should now be off, and the yellow LED should be blinking slowly, indicating that the board has power
but that no target has been set. If the red LED is on, examine the Errors tab to determine the source of the problem.
Look at the value of Scaled Feedback displayed at the top of the window, and verify that it changes if you manually
adjust the feedback sensor.
Calibrating feedback
1. Select the correct value for Feedback mode.
2. Click “Learn…” on the Feedback tab. You will be prompted to turn the output to its minimum and maximum
positions, so that readings of the feedback sensor can be determined at each extreme.
3. Examine the resulting values and adjust if desired. Your system will be safer if you set Absolute Max. and
Absolute Min. to values that the system can actually reach, so that if motion takes it past those extremes, the jrk
will automatically shut down (because of the “Feedback disconnect” error.)
4. Click “Apply settings to device”.
5. Move the system to the middle of its range.
Setting motor limits
1. Set Max. duty cycle to a safe value, like 200.
2. Set Max. current to a safe value, like 500 mA. You want values that will turn the motor but not give it enough
power to do any damage if something goes wrong.
3. Set other limits as necessary.
4. Click “Apply settings to device”.
Connecting the motor
From this point on, be prepared to shut down the system by clicking “Stop motor” or turning off your
power supply if anything goes wrong and the limits and errors set previously fail to stop the motor.
Pololu Jrk USB Motor Controller User's Guide © 2001–2014 Pololu Corporation
5. Setting Up Your System Page 41 of 45