Friday, July 31, 2015

Carputer 2015 - ODROID-XU4 SBC

The carputer project is still ongoing, just vanished down a rabbit hole for a few weeks. As it turns out, the Android OS environment is simply more compatible, stable, and easier to manage on ARM platforms than x86 PC platforms. Duh, right?

The Carputer is Dead, Long Live The Carputer!

The Carputer 2015 frontend is now powered by a US$74.00 ODROID-XU4. This capable little board contains, at its heart, the same Exynos 5422 SoC as the international variant of the Samsung Galaxy S5 smartphone. This places it a notch below 2015's flagship devices, but in a completely different class than low-cost boards like the Raspberry Pi 2 and BeagleBone Black.


Ordering the Odroid and accessories from ameriDroid went flawlessly. The order arrived quickly, well-packaged, and complete. There was even a little handwritten "thank you" note. Other Asian manufacturers would do well to emulate Hardkernel's American distribution channel.

What's on (the) Board?

It should be evident from the picture that there's a lot of I/O on this little board. So here's what we have:
  • Samsung Exynos 5422 SoC, 8 cores, 2 GB, graphics
    AnandTech provides some quick analysis and comparison.
  • Heat sink and fan
    The PWM-controlled fan kicks in as needed. I have yet to see it move.
  • Power switch
    Pulls the board out of sleep state. The board powers on automatically.
  • 2x USB 3.0 host ports
    These share an internal 2 port hub.
  • 1x GigE Ethernet port
    A wonderful and rare feature for ARM SBCs! Internally, this runs off a dedicated USB 3.0 channel.
  • 1x USB 2.0 host port
    Is this connected via an internal hub? Directly connected, no hub.
  • Full-size HDMI connector
    Nicely enough, this supports digital audio output and CEC.
  • DC power jack
    Input is specified as 5V at up to 4A. 4 amps is a lot for a small board.
  • Standard microSD card slot
  • Connector for eMMC module (underside of board)
    This supports fast 5.0 modules!
  • Boot selector switch (microSD or eMMC)
  • Serial console connector (requires cable)
  • Connector for RTC battery
    Nicely done to leave the battery off the board but easy to add!
  • Headers for digital, analog, and bus I/O
Hardkernel did a great job with the design of this board. Pretty much everything is there, and in a form that doesn't require adapters. It does bear mentioning the few features that are missing:
  • No analog audio in/out
    Digital audio is supported via HDMI, USB, and I2S headers.
  • No wireless anything
    You'll need to add WiFi, Bluetooth, GPS, etc. if you want them.
  • No USB client port
  • No power monitoring or battery management
    Some other models of Odroid have power monitoring.
Again, it was a logical choice to leave out noisy radios and audio conversion.

What about Android?

Hardkernel sells eMMC modules and microSD cards preloaded with Android or Linux. Currently shipped versions appear to be Android 4.4 KitKat and Ubuntu 15.04. Disclaimer: I have not yet tried Linux on Odroid. Android images appear to be customized versions of CyanogenMod. After playing around a bit with 4.4, I soon upgraded to the community supported 5.1 and installed the Google Apps.

The carputer plan is to use HDMI audio output and a USB microphone. Digital audio was one of those things that just didn't want to work on Android-x86. I have a Blue Tiki USB microphone that is quite good at filtering noise from voice input. This mic also provides a (semi-useless?) output channel that confuses the Android audio subsystem. This results in USB audio in or HDMI audio out, pick one. Thankfully this has a quick solution under Android 5.x. Editing the audio_policy.conf file to comment out the USB audio output section gave the desired result. Multiple audio device support remains problematic in Android.

The long-promised in-car demo shouldn't have to wait much longer!