Flashing a new BeagleBone Black from Linux (Shallow Thoughts)

Akkana's Musings on Open Source Computing and Technology, Science, and Nature.

Sat, 13 Jul 2013

Flashing a new BeagleBone Black from Linux

I finally got a shiny new BeagleBone Black! This little board looks like it should be just the ticket for robotics, a small, cheap, low-power Linux device that can also talk to hardware like an Arduino, with plenty of GPIO pins, analog, PWM, serial, I2C and all.

I plugged in the BeagleBone Black via the mini USB cable, and it powered up and booted. It comes with a Linux distro, Angstrom, already installed on its built-in flash memory. I had already known that it would show up as a USB storage device -- you can mount it like a disk, and read the documentation (already there on the filesystem) that way. Quite a nice feature.

What I didn't know until I read the Getting Started guide was that it had an even slicker feature: it also shows up as a USB network device. All I had to do was run a script, mkudevrule.sh, to set up some udev rules, and then ifconfig -a on my desktop showed a new device named eth1.

The Beagle is already configured as 192.168.7.2, so I configured eth1 to be on the same network:

ifconfig eth1 192.168.7.1
and I was able to point my browser directly at a mini http server running on the device, which gives links to all the built-in documentation. Very slick and well thought out!

But of course, what I really wanted was to log in to the machine itself. So I tried ssh 192.168.7.2 and ... nothing. It turns out that the Angstrom that ships on current BBBs has a bug, and ssh often doesn't work. The cure is to download a new Angstrom image and re-flash the machine.

It was getting late in the evening, so I postponed that until the following day. And a good thing I did: the flashing process turned out to be very time consuming and poorly documented, at least for Linux users. So here's how to do it.

Step 1: Use a separate power supply

Most of the Beaglebone guides recommend just powering the BBB through its provided mini USB cable. Don't believe it. At least, my first attempt at flashing failed, while repeating exactly the same steps with the addition of an external power supply worked just fine, and I've heard from other people who have had similar problems trying to power the BBB through cable USB cable.

Fortunately, when I ordered the BBB I ordered a 2A power supply with it. It's hard to believe that it ever really draws 2 amps, but that's what Adafruit recommended, so that's what I ordered.

One caution: the BBB will start booting as soon as you apply any power, whether from an external supply or the USB cable. So it might be best to leave the USB cable disconnected during the flashing process.

Get the eMMC-flasher image and copy it to the SD card

Download the image for the BeagleBone Black eMMC flasher from Beagleboard Latest Images. They don't tell you the size of the image, but it's 369M.

The uncompress it. It's a .xz file, which I wasn't previously familiar with, but I already had an uncompressor for it, unxz:

unxz BBB-eMMC-flasher-2013.06.20.img.xz
After uncompressing, it was 583M.

You'll need a microSD card to copy the image to. The Beagleboard folks don't say how much space you need, but I found a few pages talking about needing a 4G card. I'm not clear why you'd need that for an image barely over half a gig, but 4G is what I happened to have handy, so that's what I used.

Put the card in whatever adapter you need, plug it in to your Linux box, and unmount it if got mounted automatically. Then copy the image to the card -- just the base card device, not the first partition. Replace X with the appropriate drive name (b in my case):

dd bs=1M if=BBB-eMMC-flasher-2013.06.20.img of=/dev/sdX
The copy will take quite a while.

Boot off the card

With the BBB powered off, insert the microSD card. Find the "user boot" button. It's a tiny button right on top of the microSD card reader. While holding it down, plug in your power supply to power the BBB on. Keep holding the button down until you see all four of the bright blue LEDs come on, then release the button.

Then wait. A long time. A really long time. The LEDs should flash erratically during this period. Most estimates I found on the web estimated 30-45 minutes to flash a new version of Angstrom, but for me it took an hour and six minutes.

You'll know when it's done when the LEDs stop blinking erratically. Either they'll all turn on steady (success) or they'll all go off (failure).

Over an hour? Why so long?

I wondered that, of course, so in my second attempt at flashing, once I had the serial cable plugged in, I ran ps periodically to see what it was doing.

And for nearly half that time -- over 25 minutes -- what it was doing was configuring Gnome.

Seriously. This Angstrom distribution for a tiny board half the size of your hand runs a Gnome desktop -- and when it flashes its OS, it doesn't just copy files, it runs Gnome configuration scripts for every damn program on the system.

Okay. I'm a little less impressed with the Beagle's Angstrom setup now. Though I still think this USB-ethernet thing is totally slick.

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[ 14:30 Jul 13, 2013    More hardware | permalink to this entry | comments ]
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