3.h. Upgrading Firmware

The jrk has field-upgradeable firmware that can be easily updated with bug fixes or new features.

You can determine the version of your jrk’s firmware by running the configuration utility (Section 3.a), connecting to a jrk, and looking at the firmware version number which is displayed in the upper left corner below the “Connected to” dropdown box.

Version 1.4 of the firmware for the jrk 12v12 extends the “When motor is off” parameter so that it now affects the behavior of the jrk whenever the duty cycle is 0. Previously, at a duty cycle of 0, the jrk 12v12 would brake the motor in one direction but let it coast in the other direction. Now the default behavior is to brake in both directions, but you can configure it to coast instead. Firmware version 1.4 also makes the jrk 12v12 brake low (connect both A and B to GND) instead of braking high. All jrk 12v12s manufactured after August 24, 2012 ship with firmware version 1.4.

The latest version of the jrk 21v3 firmware available is Version 1.3. Do not attempt to load jrk 12v12 firmware onto a jrk 21v3, or vice-versa.

To upgrade your jrk’s firmware, follow these steps:

  1. Save the settings stored on your jrk using the “Save settings file…” option in the File menu. All of your settings will be reset to default values during the firmware upgrade.
  2. Download the latest version of the firmware for your motor controller here:
  3. Connect your jrk to a computer running Windows using a USB cable.
  4. Run the Pololu Jrk Configuration Utility. If there is only one jrk connected to your computer, the configuration utility will automatically connect to it. If there are multiple jrks connected to your computer, you will have to use the “Connected to” dropdown box to select which jrk you want to connect to.
  5. In the File menu, select “Upgrade Firmware…”. You will see a message asking you if you are sure you want to proceed: click Yes. The jrk will now disconnect itself from your computer and reappear as a new device called “Pololu umc01a Bootloader” or “Pololu umc02a Bootloader”.
    • Windows 10, Windows 8, Windows 7, and Vista: the driver for the bootloader will automatically be installed.
    • Windows XP: follow steps 6-8 from Section 3.a to get the driver working.
  6. Once the bootloader’s drivers are properly installed, the green LED should be blinking in a double heart-beat pattern, and there should be an entry for the bootloader in the “Ports (COM & LPT)” list of your computer’s Device Manager.
  7. Go to the window titled “Firmware Upgrade” that the Jrk Configuration Utility opened. Click the “Browse…” button and select the firmware file you downloaded.
  8. Select the COM port corresponding to the bootloader. If you don’t know which COM port to select, go to the Device Manager and look in the “Ports (COM & LPT)” section.
  9. Click the “Program” button. You will see a message warning you that your jrk’s firmware is about to be erased and asking you if you are sure you want to proceed: click Yes.
  10. It will take a few seconds to erase the jrk’s existing firmware and load the new firmware. Do not disconnect the jrk during the upgrade.
  11. Once the upgrade is complete, the Firmware Upgrade window will close, the jrk will disconnect from your computer once again, and it will reappear as it was before. If there is only one Jrk plugged in to your computer, the Pololu Jrk Configuration Utility will connect to it. Check the firmware version number and make sure that it now indicates the latest version of the firmware.

If you run into problems during a firmware upgrade, please contact us for assistance.

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