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How to Upgrade Motor Control Firmware
NexStar GPS, CPC HD Deluxe, CPC, LCM, SE, SLT, CGE, CGE Pro, CGEM and AS-GT

Celestron provides motor control firmware updates for the NexStar GPS, CPC HD Deluxe, CPC, LCM, SE, SLT, CGE, CGE Pro, CGEM and AS-GT telescopes/mounts.  (For newer mounts, read this article.)  It is recommended that you ensure your scope is running the latest version of firmware.  See Firmware Versions on this web site for a list of the current versions and how to check versions on your scope.  If the MC version is 2 or lower on the NexStar 8/9.25/11 GPS, read this to learn how to replace your motor control board as boards version 2 or lower are not upgradeable.

To update the MC firmware, first download the MCupdate program from Celestron's web site:

https://www.celestron.com/pages/drivers-and-software
search for "motor control firmware updates" or "MCupdate"

OR

https://software.celestron.com/public_release/
and download "MCupdateInstall.exe"

After downloading and installing MCupdate from the Celestron Support Downloads web site, start MCupdate and read through the Help information.  If you have problems installing MCupdate on Windows 8 or higher, right-click the downloaded file and select Troubleshoot compatibility - select the options to inform the installer it last worked correctly on Windows 7.  Note that MCupdate only runs on Windows.

There are four potential methods for connecting your PC to the scope:

WARNING - as of late 2019, the current version of firmware for the NexStar+ hand controls is NOT compatible with MCupdate.  If you attempt to update the MC firmware when connected through the NexStar+ hand control it will render the MC board inoperable and MCupdate will not be able to fix it.  In that case, downgrade the firmware on the NexStar+ hand control using these instructions, run MCupdate again to reload the firmware on your MC board, and then upgrade your NexStar+ hand control to the current firmware.

  1. For scopes with hand control version 4 (insure the hand control firmware is version 4.13 or higher) or the NexStar+/StarSense hand control with an RS-232 port (small telephone jack on the bottom), connect the serial port on your PC to the RS-232 Port on the bottom of the hand control using a Hand Control RS-232 Port Cable.  For details on this cable and sources to purchase one, read this.  If your PC does not have a serial port, you will need a USB-to-serial adapter available at most computer stores - see PC Control on this web site for more information and options regarding computers without a serial port.
  2. For scopes with a NexStar+ or StarSense hand control with a USB port on the bottom, connect your PC to the USB port.  If you have never done this before, see PC Control on this web site for more information on the cable and drivers required.
  3. When possible, use option 1 or 2, but if you have an older hand control and your scopes has a PC Port on the mount (NexStar GPS, CPC and CGE), connect the serial port on your PC to the PC Port on the mount using the PC Port Cable.  For details on this cable and sources to purchase one, read this.  Note that use of the PC Port is a potential source of difficulty - the PC port has generally been sitting exposed to the elements and may need cleaning.  If you have electronic contact cleaner, use a swab and clean the pins in the PC port jack.  If you cannot get contact cleaner, slide the plug in and out of the jack several times to wipe off any contaminants. 
  4. When possible, use option 1 or 2.  If that isn't possible and your scope does not have a PC Port on the mount, use Celestron's Auxiliary Port Accessory Kit (part number 93965 - now discontinued) which provides the required PC Port.  Connect the serial port on your PC to the PC Port on the Auxiliary Port Accessory just as described in option 3.  As another option, Ken Hutchinson has created a document describing how to build a PC Port adapter for the AS-GT, SE and SLT mounts - click here for details.  Matthias Bopp has created a document describing how to build a PC Port adapter for the NexStar "i" Series mount - click here for details.  If you do not already have one of these adapters, I would recommend you purchase the new version 4 or NexStar+ hand control and refer to option 1 or 2 above.

Important note for AS-GT mount owners:  it is not possible to update the MC firmware on the AS-GT mount through a connection to the NexStar+ or StarSense hand controls.  You must connect via the PC Port on the Auxiliary Port Accessory Kit or a version 4 hand control.

After making the connection, start MCupdate.  Here is an overview of the upgrade process:

  • First, insure you are using the latest version of MCupdate.  If you are not using the latest version of MCupdate then the following instructions may not work and the motor upgrade may fail.  Connect to the Internet and start MCupdate.  Select None for the COM port and click the Next button.  Click Download via the Web button.  If a newer version of MCupdate is available, you will be prompted to install it and MCupdate will restart.  You are now ready to update the MC firmware in your scope.
  • Connect your PC to the scope using one of the three methods discussed above.  If you are connecting to the mount via the PC Port, remove the hand control from the mount prior to powering your telescope.  If you are using hand control 4.13 or higher and connecting via the port on the bottom of the hand control do not use the INFO/UNDO button sequence to put the hand control in the programming state - this is only used when updating the hand control firmware, not the motor control.
  • Start MCupdate from the Programs section of the Windows Start menu.  If you have problems getting MCupdate to start, right-click the MCupdate icon and select Troubleshoot compatibility - then select the options to inform the installer it last worked correctly on Windows 7.
  • Insure Motor Control Board is selected as the device and click the Next button.
  • Select the correct COM Port for your connection to the scope and click the Next button.  Note that if you do not have Internet connectivity at location of your scope, you can use None for the COM Port to first download the correct firmware before disconnecting from the Internet, traveling to your scope and connecting your PC to the scope.
  • If you selected a COM Port and MCupdate cannot communicate with the scope, an error message will appear.  If you are certain your cable is good, try selecting all the other available COM Port available in MCupdate.  If that still doesn't work, you should check whether another program has the serial port open - for example, the hot sync program for a palmtop computer.  Either temporarily disable the serial port selection in the hot sync program or uninstall it altogether (if you no longer use it).  If you are still having problems, clean the PC port as described above and check to be sure that none of the pins in the port are bent.  Additional suggestions are found in the Serial Overview section of the help information in MCupdate.
  • The next screen lists all the firmware you currently have downloaded to your PC.  Click the Download via the Web button to connect to Celestron's web site and see if newer firmware is available.  This does of course require that you are currently connected to the Internet, so as mentioned before, if necessary, use COM Port "none" if you are not at your scope when downloading new firmware.  Once you have the downloaded the firmware you wish to use, be sure it is highlighted in the list and click the Next button.  Note that it is not necessary to install each version in succession until you reach the newest version - each version is a complete firmware load and stands on its own.
  • Normally you should then click the Begin Programming button with All Devices selected in the list.  Some owners have experienced difficulty in completing the upgrade in this manner.  In this case they were able to successfully upgrade by programming the azimuth and altitude separately.
  • The programmer will then proceed and should complete successfully.  If it doesn't, don't panic, just try again a few times - upgrading the azimuth and altitude separately.  If it still doesn't complete, now you can panic and call Celestron :-)

If the update is interrupted in the middle, (for example, the PC locks up or the mount is accidentally powered off) you should power off and power on the mount.  If you are updating via a PC Port on the mount or Auxiliary Port Adapter, simply repeat the update process.  If you are updating via the port on the bottom of the hand control, when you switch the power back on the hand control may display a No Response error.  If so, simply press the UNDO button on the hand control several times until the No Response message is cleared.  The hand control should then display the locked message and you will be able to continue with the update as described above.

If you were updating via the hand control and now the hand control displays Initializing and then goes blank, try resetting the hand control by powering off, holding down the 0 button and powering back up.  You may then need to attempt to reload the MC firmware.  If this doesn't work, read this for one last possible solution.

If MCupdate displays an error during programming, close MCupdate, right-click the MCupdate icon and select Troubleshoot compatibility - then select the options to inform the installer it last worked correctly on Windows 7.

Note:  The Verify Firmware option in MCupdate does not work on some of the newest Celestron mounts.  Verification does automatically occur after any new firmware is loaded.

Updating MC firmware may reset the following to default values, so it is best to make a note of the current settings prior to the upgrade:

  • anti-backlash settings
  • GoTo approach
  • autoguide rates
  • PEC recording (GPS, CPC, CGEM, CGE, CGE Pro mounts only) - use PECTool to save your current recording before the upgrade and restore the recording after the upgrade

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