Pololu Jrk USB User Manual

Pololu Jrk USB Motor ControllerUser's GuidePololu Jrk USB Motor Controller User's Guide © 2001–2014 Pololu Corporationhttp://www.pololu.com/

2. Contacting PololuYou can check the Pololu Jrk 21v3 USB Motor Controller page[http://www.pololu.com/product/1392] or the Pololu Jrk 12v12 USB MotorC

3. Configuring the Motor Controller3.a. Installing Windows Drivers and the Configuration UtilityIf you use Windows XP, you will need to have Service P

7. On the second screen of the “Found New Hardware Wizard”, select “Install the software automatically” andclick “Next”.Pololu Jrk USB Motor Controlle

8. Windows XP will warn you again that the driver has not been tested by Microsoft and recommend that youstop the installation. Click “Continue Anyway

If you use Windows XP and experience problems installing or using the serial port drivers, the cause of your problemsmight be a bug in older versions

Windows 8 device manager showing the Pololu Jrk 21v3 Motor ControllerWindows XP device manager showing the Pololu Jrk 21v3 MotorControllerSome softwar

3.b. Input OptionsThe Input tab of the Jrk Configuration UtilityThe Input tab of the jrk configuration utility contains settings for how the feedback

Input scalingThe scaling options in this tab determine how the raw input values map to target values, which determine the outputof the system. The par

3.c. Feedback OptionsThe Feedback tab of the Jrk Configuration UtilityThe Feedback tab of the jrk configuration utility controls the measurements of t

the maximum and minimum possible values of the output; these will be converted to scaled feedback values of 4095and 0, respectively. If the feedback l

1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

duty cycle target =(Proportional coefficient) × error+ (Integral coefficient) × integral+ (Derivative coefficient) × derivativeThe integral is compute

3.e. Motor OptionsThe Motor tab of the Jrk Configuration UtilityThe Motor tab of the jrk configuration utility controls the PWM [http://en.wikipedia.o

However, a higher PWM frequency means greater power loss due to switching, which could make a 5 kHz PWMfrequency a better choice for certain applicati

As of firmware version 1.4, the behavior of the jrk 12v12 when the duty cycle is zero depends on the“When motor is off” configuration option. In previ

3.g. The Plots WindowThe Plots window of the configuration utility displays real-time data from the jrk, scrolling from right to left. Toaccess this w

You can determine the version of your jrk’s firmware by running the configuration utility (Section 3.a), connecting toa jrk, and looking at the firmwa

10. It will take a few seconds to erase the jrk’s existing firmware and load the new firmware. Do not disconnectthe jrk during the upgrade.11. Once th

4. Using the Serial Interface4.a. Serial ModesThe jrk has three different serial interfaces. First, it has the RX and TX lines. The jrk can send bytes

UARTThe UART serial mode.In this mode, the TX and RX lines can be used to send commands to the jrk and receive responses from it. Anybyte received on

start bit, 8 data bits, and a stop bit, each byte takes 10 bit times to transmit, so the fastest possible data rate in bytesper second is the baud rat

Pololu jrk 21v3 USB motor controller withdimensions.Bottom of the jrk 12v12 USB motor controllerwith feedback with dimensions.1. OverviewThe jrk famil

jrk on the line whose device number matches the specified device number accepts the command that follows; allother Pololu devices ignore the command.

2. Add 7 zeros to the end of your message.3. Write your CRC-7 polynomial underneath the message so that the LSB of your polynomial is directly belowth

This command will turn the motor off by setting the Awaiting Command error bit. The jrk will not restart the motoruntil it receives a Set Target comma

Set Target Low Resolution ReverseCompact protocol: 0xE0, magnitudePololu protocol: 0xAA, device number, 0x60, magnitudeIf magnitude is zero, then this

input value. The jrk can recover from the error by receiving four good pulses in a row. This error does not occurin Analog Input Mode or Serial Input

This command is equivalent to reading the “Currently stopping motor?” column in the Errors tab of the configurationutility, and then clicking the “Cle

Read Variable Command ByteVariable RangeTwo bytes Low byte High byteInput 0 to 4095 0xA1 0x81 0x82Target 0 to 4095 0xA3 0x83 0x84Feedback 0 to 4095 0x

different from the duty cycle target because it takes in to account all of the jrk’s configurable limits: maximumacceleration, maximum duty cycle, max

ConnectionsConnect the TX line of the master device to the RX lines of all of the slave devices. Commands sent by the masterwill then be received by a

#include <fcntl.h>#include <stdio.h>#include <unistd.h>#ifdef _WIN32#define O_NOCTTY 0#else#include <termios.h>#endif// Reads

• Simple configuration and calibration over USB with free configuration program (Windows 8, Windows 7,Vista, Windows XP compatible).• Configurable par

int feedback = jrkGetFeedback(fd);printf("Current Feedback is %d.\n", feedback);int target = jrkGetTarget(fd);printf("Current Target is

5. Setting Up Your SystemThe following step-by-step procedure is recommended for configuring a feedback system for use with a jrk motorcontroller.Conn

1. Turn off power.2. Connect your motor wires to the jrk’s A and B motor outputs. If possible, connect them so that positivevoltage at A causes the mo

4. Note how close your system gets to an error of zero using just theproportional term. You can use the integral term to get it much lower:with the in

Pololu Jrk USB Motor Controller User's Guide © 2001–2014 Pololu Corporation5. Setting Up Your System Page 44 of 45

6. Writing PC Software to Control the JrkThere are two ways to write PC software to control the jrk: the native USB interface and the virtual serial p

The jrk 21v3 and jrk 12v12 each ship with a straight 0.1″ breakaway male header [http://www.pololu.com/product/965]strip and two appropriately sized 2

Pololu jrk 12v12 USB motor controller with feedback, labeled top view.The Pololu jrk USB motor controller can connect to a computer’s USB port via a U

• The red error LED indicates an error. If there is an error stopping the motor (besides the Awaiting Commanderror bit), then the red LED will be on.

Under Linux, the two virtual COM ports created by the jrk should appear as devices with names like /dev/ttyACM0and /dev/ttyACM1 (the number depends on

• The feedback is measured as a value from 0 to 4095. In analog voltage feedback mode, this represents avoltage level of 0 to 5 V. In digital frequenc