2.7 KiB
Enable Hardware Features
Some boards require some manual configuration to turn on/off certain features
In some cases, the procedure is "less than obvious", so we document some basic examples here.
Generic howto for Allwinner devices
Legacy or Vanilla kernel ?
Many Armbian images come in two flavours : Legacy (using an older kernel version) and Vanilla (up-to-date kernel). Depending on kernel version, the procedure to enable/disable features is not the same :
- Legacy kernel : FEX
- Vanilla kernel : DT (Device Tree)
What flavour am I using ?
Best way to know is by checking your kernel version :
root@bananapipro:~# uname -a
Linux bananapipro 4.5.2-sunxi #11 SMP Thu Apr 28 21:53:25 CEST 2016 armv7l GNU/Linux
In this example the kernel version is 4.5.2 so you can use DT to tweak some settings. If you get a kernel version 3.X then you'll be certainly using FEX like on an Orange Pi Plus 2E :
root@orangepiplus2e:~# uname -a
Linux orangepiplus2e 3.4.112-sun8i #10 SMP PREEMPT Wed Jun 1 19:43:08 CEST 2016 armv7l GNU/Linux
FEX
Which file should I edit
Armbian embed a lot of BIN files, but a symlink point to the one in use :
root@orangepiplus2e:~# ls -la /boot/script.bin
lrwxrwxrwx 1 root root 22 Jun 1 20:30 /boot/script.bin -> bin/orangepiplus2e.bin
Updating a FEX
You may need to use sudo with all the following commands.
The whole process won't overwrite any of your files. If you're paranoid, you can make a proper backup of your BIN file :
cp /boot/script.bin /boot/bin/script.bin.backup
Then you can decompile your BIN into a FEX :
bin2fex /boot/script.bin /tmp/custom.fex
Finally you can edit your FEX file with your favorite text editor and compile it back to a BIN :
fex2bin /tmp/custom.fex /boot/bin/custom.bin
The last step is to change the symlink to use your custom BIN :
ln -sf /boot/bin/custom.bin /boot/script.bin
Device Tree
Which file should I edit
I use the following command and try to guess which file to use in /boot/dtb/ :
cat /proc/device-tree/model
H3 based Orange Pi, legacy kernel
Enable serial /dev/ttyS3 on pins 8 and 10 of the 40 pin header
Update the FEX configuration (which is compiled into a .bin) located at /boot/script.bin
Decompile .bin to .fex
cd /boot
bin2fex script.bin > custom.fex
rm script.bin # only removes symbolic link
Edit .fex file
[uart3]
uart_used = 1 ; Change from 0 to 1
uart_port = 3
uart_type = 2 ; In this case we have a 2 pin UART
uart_tx = port:PA13<3><1><default><default>
uart_rx = port:PA14<3><1><default><default>
Compile .fex to .bin
fex2bin custom.fex > script.bin
Reboot
Notice that /dev/ttyS3 appears. That is your new UART device.