Sunday, October 25, 2015

Orange PI Plus Ubuntu 14.04 FAQ

The OrangePI Plus is a RaspberryPI-like piece of hardware that has awesome features at a great price point.  I bought a few of them to create a small ARM cluster.  Unfortunately the software needs some help (as is expected for a $39 board), but the open source community is delivering what is needed.

I chose to use the Ubuntu 14.04 XFCE distribution on my board because I wanted something solid with long term support.  This is what I discovered in my efforts.  Perhaps this FAQ will save you some time.

Kernel and Distribution

Use kernels provided by loboris described here:

Source code is here:

The kernels and distros provided by Xulong (OrangePI mfg) are not well supported, have no cleanly documented build procedure, etc.

Changing the display resolution in Lubuntu

Testing your monitor's capability

Boot your OPI+.  Now run:
sudo fbset -xres [horizontal resolution] -yres [vertical resolution]

for example:
sudo fbset -xres 1920 -yres 1080

(default password is orangepi)

This won't really work.  It will resize the screen without resizing the desktop so your desktop will now appear on the upper left area of the screen and a black or repeated desktop will appear on the bottom and the right.  But it proves that your hardware is capable of the resolution.

Setting the screen resolution in OrangePI Lubuntu

Your flash card is separated into two partitions "/" and "BOOT".  Guess what, the BOOT partition is NOT mounted at /boot, but a copy of the files in BOOT are there.  It is actually located at /media/boot.  You can verify this by running "df"

If you put your flash card in a DIFFERENT computer, you should see 2 volumes, one is called "BOOT".  Click on that and you will see a bunch of files like:

Rename the resolution you want to "script.bin" and reboot.


Enabling the Ethernet 

If your wired ethernet is not working (does not initialize and no blinky lights on the jack), you probably forgot to use the OPI+ kernel.  As above, put your flash card in a DIFFERENT computer and look at the BOOT partition.  Copy the uImage.OPI-PLUS file to "uImage".  This is the name of the linux kernel in machines that use u-boot (ARM machines).

You also need the proper kernel to use many of the other OPI hardware features...


Adding GPIO, LED, I2C and SPI access

sudo modprobe gpio_sunxi

To control the LEDs:

RED OFF: /bin/echo 0 > /sys/class/gpio_sw/normal_led/data
RED ON: /bin/echo 1 > /sys/class/gpio_sw/normal_led/data
GREEN OFF: /bin/echo 0 > /sys/class/gpio_sw/standby_led/data
GREEN ON: /bin/echo 1 > /sys/class/gpio_sw/standby_led/data

Add "gpio_sunxi" to /etc/modules to get it to autoload on boot.

Adding IR Remote Controls

sudo modprobe sunxi_ir_rx

Add "sunxi_ir_rx" to /etc/modules to get it to autoload on boot.

Enabling the analog audio output

sudo alsamixer
hit F6 (select soundcard)
select 0 audiocodec
Move right to "Audio Lineout"
Hit "m" to turn it on (should show 00 in the above box)
Hit ESC to exit 

Switching between analog and HDMI audio output

In XFCE choose XFCE Menu -> Sound & Video -> PulseAudio Volume Controls.  Go to the configuration tab.  Disable the one you don't want and audio will pop to the other.

Adding a SATA Hard Drive

This describes how to add a hard drive as additional data, not how to boot from it (you can boot from the 8GB EMMS).  There's nothing special; this is standard linux stuff:

Plug it in using SATA cable.  Power up board.

mkfs.ext4 -b 4096 /dev/sda
mkdir /data
mount /dev/sda data

(verify by ls /data.  You should see lost+found.  Also run "df")

nano /etc/fstab
/dev/sda /data ext4 defaults 0 0

WIFI Command Line Configuration

sudo nmcli -a d wifi connect
(will ask which SSID, etc)

kswapd process using almost 100% of cpu

This is a bug in the kernel.  The easiest solution is to make some swap space:

sudo -i
dd if=/dev/zero of=/swap bs=1M count=1024
chmod 600 /swap
mkswap /swap
swapon /swap  
You can then tell the system not to use swap unless it absolutely must:

sysctl vm.swappiness=0
The number is a percentage from 0 to 100 indicating how much Linux should preemptively move RAM into swap.

Don't forget to add the swap to /etc/fstab so swap is enabled on boot:

/swap swap swap defaults 0 0


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