• Please note: From a software point of view ODROID C1, C1+ and C0 are (nearly) identical. For Hardware differences between C1 and C1+ and to see how to use USB OTG on the latter please see here. C0 is a stripped down and more power efficient C1+ that can be battery powered (see here how to read out battery voltage)
• Comprehensive device information and various tips&tricks can be found in Hardkernel’s wiki. Please be aware that some of the information does not apply to Armbian (eg. we use a different partition table). Schematics can be found here.
• Idle consumption of an ODROID-C1+ with Armbian defaults varies between 1800 mW (@504 MHz) and 1900 mW (@1728 MHz — temperature also differs just by 2°C — for reasons please refer to the ‘race to idle’ concept.
• By defining setenv hdmioutput "0" and setenv vpu "0" in /boot/boot.ini followed by a reboot you get true headless mode (no consumption savings but MemTotal increases from 804 MB to 941 MB — check /proc/meminfo if in doubt)
• You can save at least 170mW by cutting power to the internal USB hub (and also all USB devices connected to any of the type A receptacles) using /sys/class/gpio/gpio4 (see description here). The same way you have full control over power consumption of a connected host powered USB disk: umount /mnt/usb && echo 0 >/sys/class/gpio/gpio4/value and echo 1 >/sys/class/gpio/gpio4/value && sleep 2 && mount /mnt/usb
• Interestingly at least on C1+ consumption remains the same if you switch from Gbit to Fast Ethernet or disable Ethernet at all. It seems the GbE PHY is powered all the time (maybe related to performance/stabiity problems on ODROID-C1 in early 2015)
• Ethernet performance is ~940 Mbits/sec in TX direction and 400-500 Mbits/sec in RX direction. You might be able to tweak the latter a little, just have a look in the link one paragraph above.
• the red led is a power led while the blue led is custom. Boot stage: as soon as u-boot is loaded the blue led lights solid and when kernel starts this changes to heartbeat blinking with default settings. Check cat /sys/class/leds/*blue*/trigger for other functionality.

Preparation

Make sure you have a good & reliable SD card and a proper power supply. Archives can be uncompressed with 7-Zip on Windows, Keka on OS X and 7z on Linux (apt-get install p7zip-full). RAW images can be written with Etcher (all OS).

Boot

Insert SD card into a slot and power the board. (First) boot (with DHCP) takes up to 35 seconds with a class 10 SD Card and cheapest board.

Login

Login as root on HDMI / serial console or via SSH and use password 1234. You will be prompted to change this password at first login. Next you will be asked to create a normal user account that is sudo enabled (beware of default QWERTY keyboard settings at this stage).