B. supported operating systems – Pololu Jrk USB User Manual
Page 7
• The
red
error LED indicates an error. If there is an error stopping the motor (besides the Awaiting Command
error bit), then the red LED will be on. The red LED is tied to the active-high output ERR, so when there is an
error, ERR will be driven high, and otherwise it will be pulled low through the LED.
• The
yellow
output status LED indicates the status of the motor. If the yellow LED is off, then an error (other
than the Awaiting Command error bit) is stopping the motor. If the yellow LED is flashing slowly (once per
second), then either the motor is off (the Awaiting Command Error bit is set) or the jrk is in speed control mode
and the duty cycle is zero. If the yellow LED is on solid, then the motor is on and the motor has reached the
desired state. For analog and pulse width feedback modes, this means that the target is within 20 of the scaled
feedback. For speed control mode, this means that the duty cycle equals the duty cycle target. If the yellow LED
is flashing quickly (16 times per second), then the motor is on and the motor has not reached its desired state.
The ERR line is an optional output that is tied to the red error LED described above. It is driven high when the
red LED is on, and it is a pulled low through the red LED when the red LED is off. Since the ERR line is never
driven low, it is safe to connect the ERR line of multiple jrks together. Please note, however, that doing this will cause
the error LEDs of all connected jrks to turn on whenever one jrk experiences an error; the ERR output of the jrk
experiencing the error will drive the LEDs of any other jrks it is connected to, even though they are not experiencing
error conditions themselves. For more information on the possible error conditions and response options, please see
The TX line transmits non-inverted, TTL (0 – 5 V) serial bytes. These bytes can either be responses to serial
commands sent to the jrk, or arbitrary bytes sent from the computer via the USB connection. For more information
about the jrk’s serial interface, see
.
The RX line is the jrk’s control input. In serial input mode, the RX line is used to receive non-inverted, TTL (0 –
5 V) serial bytes. These bytes can either be serial commands for the jrk, arbitrary bytes to send back to the computer
via the USB connection, or both. For more information about the jrk’s serial interface, see
. In analog input
mode, RX is the analog input line used to determine the system’s target output. In pulse width input mode, the jrk
measures the duration of pulses on the RX line to determine the system’s target output. Please see
for
more information on control input signals.
The FB line is the jrk’s feedback input. In analog feedback mode, the voltage on the FB line is used as a measurement
of the output of the system. In frequency feedback mode, the frequency of low-to-high transitions on the FB line is
used as a measurement of the output of the system. Please see
for more information on feedback signals.
The AUX line is an output that is generally high whenever the jrk has power. The line will only go low for two
reasons:
1. If the jrk’s microcontroller goes to sleep (because there is no VIN supply and the device has entered USB
suspend mode), the pin is tri-stated and pulled low through a resistor.
2. If the Detect disconnect with AUX option is enabled for either the feedback or the input, then the jrk will
drive AUX low for about 150 μs each PID period to check if the feedback and/or analog inputs are disconnected.
The RST pin can be driven low to perform a hard reset of the jrk’s microcontroller, but this should generally not be
necessary for typical applications. The line is internally pulled high, so it is safe to leave this pin unconnected.
1.b. Supported Operating Systems
The jrk works under Microsoft Windows 8, Windows 7, Windows Vista, Windows XP, Linux, and Max OS X 10.7 or
later.
The configuration utility works only in Windows, so the jrk must be initially configured from a Windows computer,
but after that it can be controlled from a Linux or Mac computer.
Pololu Jrk USB Motor Controller User's Guide
© 2001–2014 Pololu Corporation
1. Overview
Page 7 of 45