The C2 was the model of XO-4 Touch put into production. The XO-4 C2 production ramp happened at the end of Feb., 2013. Most C2 units are XO-4 Touch, having multi-touch touchscreens using touchscreen technology from Neonode, while some are simply XO-4, a slightly lower cost alternative.
Identification
Four bumps (arranged in a diamond shape) on the Hinge CoverXO-4 Hinge Cover.
Rev. E motherboard
Touchscreen units have a slightly recessed screen, with a narrow (1 mm) black stripe between the gray bezel and the display.
C2 laptops will be produced with a variety of keyboard, memory, eMMC storage, language, and other options. A SKU is assigned to a particular set of options, and identified in the battery compartment.
Photographs:
Actually an A2 motherboard. Changes are minor, however. To be updated when new motherboards become available.
This will not work on an XO-1, XO-1.5, or XO-1.75. As with XO-1.75, Open Firmware and the EC firmware are separate --- Open Firmware contains a recent version of the EC firmware and will automatically update an older version given two sources of power, but a more recent version may actually be programmed into the EC.
It is strongly recommended that you have two sources of power (a charged battery and an external power source) when you upgrade your EC or Open Firmware. Failure to do so may require the use of an SPI programmer to recover your laptop.
Upgrading the EC code
Using Open Firmware and WiFi
requires Q7B01 or later
ok wifi name
ok flash-ec http:\\dev.laptop.org\pub\ec\cl4-7_0_4_11.img
Reading http:\\dev.laptop.org\pub\ec\cl4-7_0_4_11.img
Scan for: name found
Associate with: name
DHCP got 10.0.0.170
EC firmware verison: XO-EC 7 0.4.11
Erasing ...
Writing ...
fff0
Verifying ...
fff0
Board powers down at this point due to EC restart. Power up manually.
To install an image onto the external SD card, you need to type:
devalias fsdisk ext:0
fs-update u:\os1.zd
... and then power down, remove the SD card, and insert it in the XO-4.
Setting the Date
The simplest way to set the date after replacing/changing the RTC battery is boot into Open Firmware and type:
wifi <your_essid>
ntp-set-clock
Restrictions
There are no known hardware problems with the C2 model of XO-4.
Spanish Mechanical Keyboard
The XO-4 Touch SKU 301 laptops were built using an incorrect value for the KA manufacturing tag. As a result, some of the keys (such as \) aren't properly mapped when using Open Firmware (<trac>12645</trac>). While there are workarounds (e.g. \ may be found as ALT-GR 7), this problem is easy to correct:
As with XO-1.75, there is a second serial port provided for deep debugging of kernel issues. Unlike XO-1.75, this serial port is not populated by default. If you need to use this serial port, you will have to populate CN23, Q38, Q44, R408, R373, and R98. Like the main serial port, this one operates at +3.3V (using a voltage translator on the motherboard, as the actual SoC pins only tolerate +1.8V).
