ODROID

There are two ODROID U2 for development of small robots. Here are details and suggestions for their use.

Useful How-Tos

• Kernel recompiling process for the ODROID-U2; it is necessary to do this if you ever wish to install external/out-of-tree drivers, as the "official package" is missing several critical kernel headers.

Unresolved issues

Wireless Networking

Wireless communications seem to be very troublesome, as the network interfaces tend to lose or drop a lot of packages, both in RX and TX, to the point that a reliable SSH connection cannot be established. This happens at least with the "officially supported" wireless NIC (with a Realtek RTL 8191SU chipset).

 root@odroid:~# ifconfig wlan6
 wlan6     Link encap:Ethernet  HWaddr **:**:**:**:**:**
          inet addr:192.168.1.60  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: fe80::ee1a:59ff:fe0e:f122/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:453 errors:0 dropped:600 overruns:0 frame:0
          TX packets:292 errors:0 dropped:7 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:79264 (79.2 KB)  TX bytes:35116 (35.1 KB)

Realtek RTL8192CU

This chipset seems not to be even detected by the stock HK kernel, but it is possible to use it after recompiling the kernel, disabling the in-kernel module for the NIC, and integrating Realtek's official driver for this chipset inside it (instructions are included in the package).

However, you still get a huge packet loss rate, even if you disable the power saving feature of the driver by loading the kernel module with

 sudo modprobe 8192cu rtw_power_mgnt=0

Tested OS and versions

• Xubuntu 13.04 for armhf architectures, released by HardKernel with their modified Linux kernel, version 3.0.75. The kernel can be recompiled for using 3D video acceleration but this would prevent USB video cameras to work, so it's useless for robot development (even more so since OpenCL can't be even used).

Note: in this version of the OS, the lshw command seems to be partly broken, but this is resolved by calling it with

 sudo lshw -disable dmi

although this will prevent the detection of certain features of the board.

Tested I/O devices

Monitors

Monitors need a native HDMI interface to work with ODROIDs due to the strict requirements of the Exynos system-on-chip; for the same reason, external HDMI-to-DVI adapters are also not recommended, as you could result having a blank image screen (source )

This is a list of monitors and TV screens with native HDMI ports that are known to work.

• Sony KDL-32V4500
• Samsung Syncmaster XL2370 HD