Nov 072013

Tonight we recovered a beagleboard! Many months ago we tried to install Debian and lost video and network access to the device. Obviously, U-Boot wasn’t able to boot the broken Debian install attempt.

beaglebone-black-serialWe attempted to re-flash using the SD card and that didn’t work. So, we thought it was broken at a deeper level and thought serial access would be helpful. A few meetings ago we attempted to build a serial cable that would interface with the BBB. We tried a standard rs232 serial cable and matched the pinout to the BBB board serial pins. Much continuity testing with a multimeter was required to match up pins. Yet, nothing we did worked. Then we realized that its not rs232 and is in fact TTL Serial (a description of the difference). Sam bought a TTL to USB controller and we used a ribbon cable and a breadboard to hook them up.
Once we successfully connected to the BBB over serial we saw the BBB was outputting the character “C”. CCCCCCCCCCCCCCCCCC…..
We asked on #beagle and the user magyarm told us that the C output means that the BBB can’t boot and all we need to do is re-flash the eMMC from a SD card. We previously had tried this and it didn’t work so the consensus was that we did it wrong. We retried the flashing of eMMC using the SD and we are happy to report a success!

We downloaded Robert Nelson’s Debian install image at


unxz BBB-eMMC-flasher-debian-7.2-2013-10-25.img.xz

dd if=BBB-eMMC-flasher-debian-7.2-2013-10-25.img of=/dev/sd[x] bs=1M

Then place the microSD in the BBB, hold down the boot button, apply power (use the power cord, because when flashing, the BBB consumes more power than the usb cable can provide), hold the boot button until the first LED comes on (this will boot from the microSD card). Wait for the bank of 4 LEDs to stop flashing and go solidly lit, it takes many minutes depending on the speed of your SD card. Once those 4 LEDs are solidly lit, the eMMC is flashed. Remove power, remove SD card and re-power on. It should now boot from internal eMMC!

Instead of blindly trying to flash, we had the serial output of the BBB and knew exactly what was going on the entire time! YAY! Instead of guessing whats going on.

Hardware options:


  3 Responses to “beaglebone black recovery”

  1. I have a question:
    How do you find different blogs on Blogger with keyword or search?


    Blog Administrator Edit: It is a worthy question, Q, but probably not one you should ask of a website running WordPress, Blogger’s dreaded arch-rival (joke).

    Additionally, I can find no evidence (given only a few minutes of looking, that is) that Blogger is free software (to be clear, I mean libre, not gratis) or open-source software. What Blogger


    is ‘Software-As-A-Service’, which at least one leading personality in the field of free software decries as being antithetical to the philosophy of software freedom: namely, Richard Stallman.
    Therefore, it kind of lies outside our expertise.
    In contrast, WordPress is open source, free, and available either ‘as a service’ (hosted on

    for convenience), but also as a software package installable to any server you own (or have install access to; many website hosting companies offer a preinstalled version of WordPress).

    However, in the interests of helpfulness, try Example: A screenshot of Google Blog Search with the query 'crunchly', limited to homepages.?

    If you ever have a corporeal form, feel free to stop by the Santa Fe Baking Company on alternate Thursdays; we would love to have you for some conversation and free pastries. If not, you might want to choose a different website to spam.


  2. Man, underline really messed up there, not sure why. I do not think I will even try to fix it (guessing comments are not really meant to have rich formatting, judging by the badly-resized image).
    Also I find it interesting that, despite having an apparently what-you-see-is-what-you-mean(t) interface, WordPress turns a double dash/hyphen into an em dash, and turned the first three dots (periods, full stops, yadayadayada) in your description of the ‘C’ output into an ellipsis.

    But anyway, editing that spam comment gave me a chance to read the blog post itself. Fun times! Why did the original Debian install not work?