RPi Easy SD Card Setup - eLinux.org

Lapdock uses the HDMI plug to tell if a phone is plugged in by seeing if the HDMI
DDC/CEC ground pin is pulled low. If it's not, Lapdock is powered off. As soon as you
plug in a phone or RasPi, all the grounds short together and Lapdock powers itself on.
However, it only does this if the HDMI cable actually connects the DDC/CEC ground
line. Many cheap HDMI cables do not include the individual ground lines, and rely on a
foil shield connected to the outer shells on both ends. Such a cable will not work with an
unmodified Lapdock. There is a detailed 'blog entry on the subject at element14:
Raspberry Pi Lapdock HDMI cable work-around (http://www.element14.com/
community/groups/raspberry-pi/blog/2012/09/27/raspberry-pi-lapdock-hdmi-cable-workaround)
. The 'blog describes a side-benefit of this feature: you can add a small power
switch to Lapdock so you can leave RasPi attached all the time without draining the
battery.
The Lapdock Micro USB plug is the upstream port of Lapdock's internal USB hub, and
connects to one of RasPi's full-size USB ports. Lapdock is not USB compliant since it
provides upstream power on its Vbus pin. Lapdock uses this to charge the Atrix phone.
You can use this feature to power RasPi if you have a newer RasPi. The original RasPi
rev 1 has 140 mA polyfuses F1 and F2 to protect the USB ports, which are too small for
powering RasPi using upstream power. Newer RasPis replace F1 and F2 with zero Ohm
jumpers or eliminate them entirely, which allows Lapdock to provide power. If you don't
mind modifying your original RasPi, you can add shorting jumpers over F1 and F2 or
replace them with higher-current fuses.
What gets powered on depends on whether Lapdock is open or closed. If it's open, the
screen and all Lapdock USB ports are powered. If you close Lapdock, the screen and
full-size USB ports are powered down, but the Micro USB still provides upstream power.
This is for charging an Atrix phone. When you open or close Lapdock, the Micro USB
power switches off for about a second so if your RasPi is connected it will reboot and you
may have a corrupted file system. There's discussion about this at the RasPi forum link,
and someone has used a supercapacitor to work around the problem: Raspberry Pi
lapdock tricks (http://www.element14.com/community/groups/raspberry-pi/blog/2012/09/
11/raspberry-pi-lapdock-tricks) .
DVI
With an inexpensive passive HDMI to DVI-D cable or converter.
Composite video
Composite video (NTSC and PAL) via an RCA plug, directly from the board. You can
change between PAL and NTSC output by editing config.txt in the boot SD card.
Uncommenting: sdtv_mode=2 sets output to PAL (see RPi_config.txt).