Power On/Off switch

You can control power supplying to ODROID-C2 while DC adaptor is connected with external switch, Sliding or Toggle Switch for example, if you connect such switch to J4 on the board. J4 is connected to NCP372 (Protection IC). There is an ENABLE pin on the NCP372 and it is a low-active and have an internal pull-down resistor for default on.

Switch status	Output of NCP372
ON(short)	OFF
OFF(open)	ON (+5V)

With this hacking, we strongly recommend to shutdown the O/S completely before turn-off. Otherwise the file system could be corrupted very easily. In Linux, for example, please make sure to execute shutdown -r now or poweroff.

Alternative power input

The J8 pins are added for an alternative power input (for easier wiring/soldering to power supply cable on PCB rev0.2 20160226)

Alternative heartbeat LED

If you want to remap the blue heartbeat LED to other GPIO, refer this great instruction.

paulcrawford's guide on the forum

IR Remote Controller (Android)

Manufacturer Code: 0x4DB2

Button	IR code	Scancode	Android
Power	0xDC	116	KEYCODE_POWER
Mute	0x88	113	KEYCODE_VOLUME_MUTE
Home	0x82	102	KEYCODE_HOME
OK	0xCE	97	KEYCODE_DPAD_CENTER
Up	0xCA	103	KEYCODE_DPAD_UP
Left	0x99	105	KEYCODE_DPAD_LEFT
Right	0xC1	106	KEYCODE_DPAD_RIGHT
Down	0xD2	108	KEYCODE_DPAD_DOWN
Menu	0xC5	139	KEYCODE_MENU
Back	0x9A	158	KEYCODE_BACK
Volume Down	0x81	109	KEYCODE_VOLUME_DOWN
Volume Up	0x80	104	KEYCODE_VOLUME_UP

The IR remote key map is defined in /system/etc/remote.conf file.
Default IR protocol is NEC type.

USB Hub IC reset script

If you need to do power-cycle to the USB devices on the USB host ports, run below commands.
It will reset all the USB devices connected to the USB host ports.

echo 126 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio126/direction
sleep 1
echo 0 > /sys/class/gpio/gpio126/value
sleep 1
echo 1 > /sys/class/gpio/gpio126/value
echo 126 > /sys/class/gpio/unexport
sleep 1

USB Hub IC issue

Every power cycle, the USB hub controller is disconnecting the USB devices at among 5~7 second after starting the boot process.
If you use a fast booting OS like Buildroot, Yocto and Ubuntu-Minimal, your USB devices will not work correctly.
To avoid this issue, you need to run your USB application software slightly later after complete the booting process.

Here is an example of the serious problem. Unfortunately, we couldn't find any workaround yet.
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