This section documents how to use the BBB as an external flashrom programmer, for reading and writing an SPI flash chip.
Shopping list (pictures of this hardware is shown later):
With my PSU, first I had wire up the mains power cable. Any clover or kettle lead will do. Cut the end off (not the one that goes in the wall, but the kettle/clover connector). Strip the protection away by a decent length, then strip the wires inside so that a decent amount of copper is shown. Then wire up earth/live/neutral. This will vary according to what country you live in and/or the colour codes that your cable uses inside. Make sure to get this right, as a botched job could result in extreme damage to you and your surroundings. Here's what mine looks like after wiring up the power cable: images/x200/psu_power.jpg - also, make sure that the plug (for the wall) has the correct fuse. In my case I had a 240V wall socket, and the device says that it accepts 1.5A at that voltage, so I used the smallest fuse available (3A). For 110-120V the device says it needs 2.8A. Also, if yours looks like in the image linked above, make sure to wrap electrical tape (lots) around it for safety. (otherwise, don't touch the terminals while the PSU is plugged in).
Now take a red and black 20cm female-female jumper lead, and cut one of the ends off. Strip away the bare copper by about 1 or 1.5cm so you get this: images/x200/stripped_jumper_lead.jpg.
Black goes on 0V, red goes on +V. In my case, I removed those screws from my PSU like this: images/x200/psu_screws_removed.jpg. Then,
Then I twisted the exposed copper on the jumper leads (so that they don't fray), and wrapped each to one of the screws each, around it near the head. I then screwed them in: images/x200/psu_jumper_leads.jpg.
If you are using a different PSU, then the steps will change from those above. Anyway, once you are satisfied, continue reading...
Your BBB will have an sshd with no password on root. Find it's IP address (it will use DHCP by default) and set a root password. The steps below are done while SSH'd into a BBB.
You can also use a serial FTDI debug board, with GNU Screen (example):
# screen /dev/ttyUSB0 115200
images/x200/ftdi.jpg and
images/x200/ftdi_port.jpg
show an FTDI debug board in use. With screen you can then login as root, like you would using SSH.
Using this, you can also see text output (from kernel, etc) when booting the machine.
You can also simply connect the USB cable from the BBB to another computer and a new network interface will appear,
with it's own IP address: this is the BBB. You can SSH into that. Or, you can (example):
# screen /dev/ttyACM0 115200
These instructions may or may not work for you. They are simply the steps that this author took.
setting up SPIDEV on the BBB: http://elinux.org/BeagleBone_Black_Enable_SPIDEV#SPI0 - If you only setup SPI0, you don't have to disable the HDMI out. (you only need one). That guide is for seting up the device overlay for SPIDEV, last part is to make it persist across reboots. Needed to turn the BBB into an SPI flasher.
Don't bother modifying uEnv.txt. it won't work; use the workaround here instead: http://elinux.org/Beagleboard:BeagleBoneBlack_Debian#Loading_custom_capes.
Follow the instructions at http://elinux.org/BeagleBone_Black_Enable_SPIDEV#SPI0 up to (and excluding) the point where it tells you to modify uEnv.txt
You need to update the software on the BBB first. Before being able to use apt-get,
I had to use the workaround defined here:
- Replace the contents of /etc/init.d/led_aging.sh with:
#!/bin/sh -e
### BEGIN INIT INFO
# Provides: led_aging.sh
# Required-Start: $local_fs
# Required-Stop: $local_fs
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Start LED aging
# Description: Starts LED aging (whatever that is)
### END INIT INFO
x=$(/bin/ps -ef | /bin/grep "[l]ed_acc")
if [ ! -n "$x" -a -x /usr/bin/led_acc ]; then
/usr/bin/led_acc &
fi
Run apt-get update and apt-get upgrade then reboot the BBB, before continuing.
Run those commands:
# echo BB-SPI0-01 > /sys/devices/bone_capemgr.*/slots
Then I did:
# ls -al /dev/spidev0.*
ls: cannot access /dev/spidev0.*: No such file or directory
Then I rebooted and did:
# cat /sys/devices/bone_capemgr.*/slots
Output:
0: 54:PF--- 1: 55:PF--- 2: 56:PF--- 3: 57:PF--- 4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G 5: ff:P-O-L Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
And then:
# ls /lib/firmware/BB-SPI0-01-00A0.*
Output:
/lib/firmware/BB-SPI0-01-00A0.dtbo
Then:
# echo BB-SPI0-01 > /sys/devices/bone_capemgr.*/slots
# cat /sys/devices/bone_capemgr.*/slots
Output:
0: 54:PF--- 1: 55:PF--- 2: 56:PF--- 3: 57:PF--- 4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G 5: ff:P-O-L Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI 7: ff:P-O-L Override Board Name,00A0,Override Manuf,BB-SPI0-01
Then check if the device exists:
# ls -al /dev/spidev0.*
Output:
ls: cannot access /dev/spidev0.*: No such file or directory
It didn't exist under that name, but I then did:
# ls -al /dev/spid*
Output:
crw-rw---T 1 root spi 153, 0 Nov 19 21:07 /dev/spidev1.0
Now the BBB is ready to be used for flashing. Make this persist
across reboots:
In /etc/default/capemgr add CAPE=BB-SPI0-01 at the end
(or change the existing CAPE= entry to say that, if an
entry already exists.
Get flashrom from libreboot_util release archive, or build it from libreboot_src/git if you need to. An ARM binary (statically compiled) for flashrom exists in libreboot_util releases.
Now test flashrom:
# ./flashrom -p linux_spi:dev=/dev/spidev1.0,spispeed=512
Output:
Calibrating delay loop... OK. No EEPROM/flash device found. Note: flashrom can never write if the flash chip isn't found automatically.
This means that it's working (the clip isn't connected to any flash chip, so the error is fine).
Use this image for reference when connecting the pomona to the BBB: http://beagleboard.org/Support/bone101#headers (D0 = MISO or connects to MISO).
The following shows how to connect clip to the BBB (on the P9 header), for SOIC-16 (clip: Pomona 5252):
NC - - 21 1 - - 17 NC - - NC NC - - NC NC - - NC NC - - NC 18 - - 3.3V PSU RED 22 - - NC - this is pin 1 on the flash chip This is how you will connect. Numbers refer to pin numbers on the BBB, on the plugs near the DC jack.
The following shows how to connect clip to the BBB (on the P9 header), for SOIC-8 (clip: Pomona 5250):
18 - - 1 22 - - NC NC - - 21 3.3V PSU RED - - 17 - this is pin 1 on the flash chip This is how you will connect. Numbers refer to pin numbers on the BBB, on the plugs near the DC jack.
NC = no connection
DO NOT connect 3.3V PSU RED yet. ONLY connect this once the pomona is connected to the flash chip.
You also need to connect the BLACK wire from the 3.3V PSU to pin 2 on the BBB (P9 header). It is safe to install this now (that is, before you connect the pomona to the flash chip).
if you need to extend the 3.3v psu leads, just use the same colour M-F leads, but keep all other leads short (10cm or less)
images/x200/5252_bbb0.jpg and images/x200/5252_bbb1.jpg shows a properly wired up BBB with Pomona 5252 before being connected to the flash chip on the X200.
That's basically it. Now refer back to the installation page for how to use this on your board.
Copyright © 2014, 2015 Francis Rowe <info@gluglug.org.uk>
This document is released under the Creative Commons Attribution-ShareAlike 4.0 International Public License and all future versions.
A copy of the license can be found at ../license.txt.
This document is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See ../license.txt for more information.
