Acer Chromebook Spin 714 (KANO)

CCD with Suzyq cable

With Chromebooks there is an option called “Closed Case Debugging”. A special usb cable called a SuzyQ cable is required. A good guide on using the SuzyQ cable is MrChromebox.

Disable Hardware Write Protection

The first thing you need to do is remove the battery of the laptop to disable hardware write protection (but then we disable hardware write protection with the echo commands to /dev/ttyUSB0?)

TODO: insert images from https://github.com/linuxboot/heads/pull/2133

Connect the USB-C end of the Suzy-Q cable to the CCD port on your ChromeOS device (usually left USB-C port) and the USB-A end to your Linux device Verify the cable is properly connected:

$ ls /dev/ttyUSB*
/dev/ttyUSB0  /dev/ttyUSB1  /dev/ttyUSB2

This command should return 3 items: ttyUSB0, ttyUSB1, and ttyUSB2. If not, then your cable is connected to the wrong port or is upside down. Adjust and repeat command until output is as expected.

TODO: Do we need to run gsctool from ChromeOS? I did not have to but maybe the previous owner of my Kano device did it? source

Now we disable software write protection:

sudo -s
echo "wp false" > /dev/ttyUSB0
echo "wp false atboot" > /dev/ttyUSB0
echo "ccd reset factory" > /dev/ttyUSB0

Extra step (What is this really doing?)

KANO requires an extra step before we flash with flashrom:

# Get the baud rate
$ sudo stty -F /dev/ttyUSB2
speed 9600 baud; line = 0;

sudo minicom -D /dev/ttyUSB2

run: apshutdown
wait 5s
run: gpioset en_S5_rails 1

source

Backup

TODO: add section about backing up rom first.

Flash heads

sudo flashrom --programmer raiden_debug_spi:target=AP,custom_rst=True \
  --chip "W25Q256JV_M" \
  --write heads-kano-202607081551-v0.2.1-3112-gb9dfd39.rom