ODROID

There are two ODROID U2 and two U3 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.

Tested OS and versions

• Lubuntu 13.05 Server does not have a graphical interface. It has already installed ssh. To install ROS, please follow these instructions
• 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).
• Linaro Ubuntu 12.11 with HardKernel's Linux kernel, version 3.0.60. Grab this image dated 25-01-2013, flash it on your microSD card and then apply the latest point kernel point update (at the time of writing, it is version 3.0.63, dated 13-02-2013) following the instructions given on the thread's opening post.

All OSes have wireless networking issues, please read below for more information.

Tested I/O devices

TP-LINK WN725n v2

This device is not supported by linux, thus it should be compiled to the desire platform. To do this, it could be follow this tutorial.

Sometimes it is not enough just the tutorial, because the system does not add the wlanX to the configuration file. Thus, it is necessary to modify the following file:

sudo vim /etc/network/interfaces

In the file add the following lines:

auto wlanX
iface wlanX inet dhap

Where X is the number of the net, that could be found using the this line:

iwconfig

After saving the changes on the file, it should be restart the connection:

sudo /etc/init.d/netwroking restart

If this command does not work reboot the system:

sudo reboot now

To see the available wifii networks:

sudo iwlist wlanX scanning

If this does not work try

 sudo ifconfig wlanX up

Then, redo the above steps

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

Unresolved issues

Wireless Networking (all tested OSes)

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 RTL8191SU chipset), even if the wifi signal strength is excellent.

A curious aspect of this issue is that only incoming packets get dropped a lot, while outgoing packets are very modestly affected.

This being said, the RTL8191SU adapter loses some packets along the way also while being connected to other computers, so maybe it's really not the best USB wifi adapter ever.

 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)

 odroid@odroid:~$ iwconfig wlan6
 wlan6     IEEE 802.11bg  ESSID:"MyWirelessNet"  Nickname:"<WIFI@REALTEK>"
         Mode:Managed  Frequency:2.437 GHz  Access Point: **:**:**:**:**:**
         Bit Rate:54 Mb/s   Sensitivity:0/0  
         Retry:off   RTS thr:off   Fragment thr:off
         Encryption key:****-****-****-****-****-****-****-****   Security mode:open
         Power Management:off
         Link Quality=100/100  Signal level=100/100  Noise level=0/100
         Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
         Tx excessive retries:0  Invalid misc:0   Missed beacon:0

Realtek RTL8192CU

This chipset seems not to be even detected by the stock HK kernel (all versions of it), 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

Solved issues

lshw glitches (all tested OSes)

With the stock kernel 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. Another way of fixing this issue is to recompile the kernel by hand (see the how-to linked above).