Updating Celestron Telescope Firmware

Here’s how I update the firmware in my Celestron 6SE telescope from my Ubuntu Linux system. There’s another nice guide here, but it didn’t work on my computer until I figured out the trick below of changing the port name.

Kudos to Celestron for writing the software in Java so it can run on any computer, Windows, Mac or Linux!

My scope has a phone-type connector to the handset and came with a cable that is a 9-pin serial on the other end. Plug this cable into your computer’s serial port and into the bottom of the handset. While the scope is off, hold down the handset Celestron & Menu buttons while turning it on. The handset will say Boot Loader Serial or something like that to indicate it’s in firmware update mode.

Now, find the Linux device file for your serial port by entering this command: dmesg | grep tty

My output looks like this; yours may be different:

[    0.000000] console [tty0] enabled
[    0.671956] 00:06: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A

On my computer, the serial port is /dev/ttyS0

Check this device file’s permissions and ensure you can read & write it. Typically you need to be in the dialout group, or just chmod the device file to 666 to open it to anyone.

Follow Celestron’s instructions to download the CFM software from their web site. Once installed, go to its directory and run it with Java: java -jar CFM.jar

When it starts it will tell you it can’t find the serial port. Select Options|Connections from the menu. In the dialog that appears, you’ll notice it says COM4 (or something similar) as the serial port name. Replace this with ttyS0 (or whatever your port’s name is).

Now click Seek Devices from the app main screen and it will find your telescope. Click the main screen Update button and CFM will find and download the latest firmware for your scope and install it.