Ubuntu-RT-UP-Board

An UP board Ubuntu real-time patched kernel (4.4.86).

Grab & Go!

Here's a compiled image for UP Board. Copy and paste following in your terminal:

wget -c "https://github.com/QiayuanLiao/Ubuntu-RT-UP-Board/releases/download/UP-board-4.4.86-rt99/UP-board-4.4.86-rt99.tar.xz" && tar -xvzf UP-board-4.4.86-rt99.tar.xz

You are all set now! For the next step:

If you need help to replace the kernel or install Ubuntu, please follow the link and read on.
To test this kernel please refer to Configuration and Test
Also if you want to build from source, here is the tutorial.
Finally, here's a step by step tutorial to build from generic kernel

Features

The UP board patches is modify from this repo to work with kernel version 4.4.86
Supported Buses:
- GPIO
- UART
- SPI
- I2C
- LEDs
Unsupported:
- HDMI Audio
- PWM(frequency error)

Help Desk

Replace the kernel

Copy the Debian packages to UP board

Remove all the generic installed kernel

sudo apt-get autoremove --purge 'linux-.*generic'

Go to the file of debian packages and install the kernel:
```
sudo dpkg -i linux-*.deb
```
Reboot
```
sudo reboot
```
Verify that the kernel is indeed installed by typing
```
uname -v
```
you should get
```
#1 SMP PREEMPT RT xxxxxxxx
```

Install Ubuntu

Download Ubuntu 16.04.6 ISO from the Ubuntu download page (works with desktop and server edition)

http://releases.ubuntu.com/16.04/ubuntu-16.04.6-desktop-amd64.iso http://releases.ubuntu.com/16.04/ubuntu-16.04.6-server-amd64.iso
Burn the downloaded image on a USB stick. We suggest to use etcher for doing that. You can download it from:

https://etcher.io
Insert the USB thumb drive in a empty USB port and proceed with a normal Ubuntu installation.

Build from source

Get the source:

git clone git@github.com:QiayuanLiao/Ubuntu-RT-UP-Board.git
cd Ubuntu-RT-UP-Board

Config the kernel:

cp .config kernel
cd kernel
make menuconfig

selet save and exit

Make the kernel

make -j`nproc` && make -j`nproc` bindeb-pk

Then you will get:

linux-firmware-image-4.4.86-rt99_4.4.86-rt99-1_amd64.deb
linux-headers-4.4.86-rt99_4.4.86-rt99-1_amd64.deb
linux-image-4.4.86-rt99_4.4.86-rt99-1_amd64.deb
linux-libc-dev_4.4.86-rt99-1_amd64.deb

Build from generic kernel step by step

Get kernel from:

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/snapshot/linux-4.4.86.tar.gz

and decompress.

Get RT_PREEMPT patch from:

https://mirrors.edge.kernel.org/pub/linux/kernel/projects/rt/4.4/older/patches-4.4.86-rt99.tar.xz
Get UP board patches from release

https://github.com/QiayuanLiao/Ubuntu-RT-UP-Board/releases/download/UP-board-4.4.86-rt99/UP-borad-patches.tar.xz
Copy patches-4.4.86-rt99.tar.xz to linux-4.4.86, then patch:
```
unxz -cd patches-4.4.86-rt99.tar.xz | patch -p1
```
Copy UP-borad-patches.tar.xz to linux-4.4.86, then patch:
```
unxz -cd UP-borad-patches.tar.xz | patch -p1
```
Config and make

Configuration and Test

Config and test HAT device

Check if there are two SPI device

ls /dev/spidev*

you should get:

/dev/spidev2.0  /dev/spidev2.1

Enable the HAT functionality from userspace

sudo add-apt-repository ppa:ubilinux/up
sudo apt install upboard-extras
sudo usermod -a -G gpio ${USER}
sudo usermod -a -G leds ${USER}
sudo usermod -a -G spi ${USER}
sudo usermod -a -G i2c ${USER}
sudo usermod -a -G dialout ${USER}
sudo reboot

Go to the /test file run the ./blink.sh
```
cd test
sh ./blink.sh
```
then the green led of UP board will blink
For HAT test, check

https://wiki.up-community.org/Pinou

Real time test using latency plot under the stress

Install requirement

sudo apt install rt-tests stress gnuplot

Go to the /test file and Run the RT test
```
cd test
sudo sh  ./rt-test.sh
```
The latency plot look like this:
Analysis:
- More sample on the left means lower latency in general
- More clustered samples indicate less flutter
- The max latency should not deviate far from mean value (typically under 100us)

Credits

@dicarlo236 helped a lot through out patching work.

qiayuanl/Ubuntu-RT-UP-Board