Setting up Kermit to work with the Gumstix

One of the most direct ways to talk to a Gumstix is via a serial port. Though a serial port is rather slow and is not the best for day to day operation, it comes in handy to do initial setup and repair. It’s also useful for flashing the Gumstix and installing a custom kernel and filesystem. Since I’m running a Linux host machine, I have two options for programs for connecting via serial: minicom or kermit. I started off using minicom because it was in the Arch Linux software repositories and because the configuration was very easy. However the problem is that the Gumstix cannot receive minicom file transfers, which make minicom useless for reflashing the Gumstix.

After compiling Kermit from source and starting it on the proper device, there are a number of options to be set before one can actually connect to the Gumstix. Doing this everytime is extremely tedious and error-prone so it’s easiest to create a simple script with the following:

#!/usr/bin/kermit +
kermit -l /dev/ttyUSB0
set speed 115200
set reliable
set carrier-watch off
set flow-control none
set prefixing all
set file type bin
set rec pack 4096
set send pack 4096
set window 5

I saved this script under the name konnect and placed it directly in my /bin directory. After marking it as executable with a sudo chmod +x konnect, I could execute the script and have it open up Kermit with all the required configurations in place. If you want to use this script, you should change /dev/ttyUSB0 to whatever serial device your Gumstix is actually connected. My laptop doesn’t have serial ports so I connect via a USB-serial adapter. You should also make sure that the device can be accessed by the user you run the script as or else it will keep throwing up permission denied messages. If you don’t want to mess with file permissions, you can run it as root via su or sudo.

4 thoughts on “Setting up Kermit to work with the Gumstix

  1. Thanks Shrutarshi for the kermit connection description to the Gumstix over USB-Serial dongle.

    Compile kermit on Linux
    1. download kermit linux source from:
    2. untar, build
    $ mkdir kermit_src
    $ cd kermit_src
    $ tar -zxvf cku211.tar.gz
    $ make linux
    4. Install as root
    $ sudo make install
    5. Set kermit permissions or run kermit as root (/usr/local/bin/kermit)
    $ sudo chmod +x /usr/local/bin/kermit
    $kermit -l /dev/ttyUSB0

  2. @ John: just do as Edward suggests, it’s a standard linux source install. Though make sure you have all the required build tools before.
    @Edward: No problem, I’m glad you found it useful.

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