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Running VU Server from source code on Linux

You can run VU Server from source code.

In order to do this you will need to install Python (programming language used by VU Server) and optionally Git.

To do this you can run the following command

sudo apt install git python3 python3-pip

Then you can clone the VU Server repository and install project dependencies

git clone https://github.com/SasaKaranovic/VU-Server.git
cd VU-Server
pip3 install -r requirements.txt

You will need to run the above steps only once.

After that you can start VU server by running python3 server.py

Now you can access VU server web GUI by navigating to http://localhost:5340 in your browser.

How to fix "OSError: [Errno 13] Permission denied: '/dev/ttyUSBx'" error

On some distributions you will need to explicitly allow access to /dev/ttyUSBx where x is usually a number (ie /dev/ttyUSB0).

There are multiple ways to do this.

You can temporarily grant access by running sudo chmod 666 /dev/ttyUSB0.

But you will have to run this command every time you re-plug in the hub, which is not very practical.

More permanent solution involves creating a udev rule

# navigate to rules.d directory
cd /etc/udev/rules.d
#create a new rule file
sudo touch vu-rule.rules
# open the file
sudo nano vu-rule.rules
# add the following
KERNEL=="ttyUSB0", MODE="0666"

Please note that you will have to reboot your machine in order for new udev rules to take effect.

Example command line usage

Ideally you would have an application/service/script that updates VU dials for you.

But in some instances you might want to update the VU dials from the command line.

This example shows how to do this.

Requirements

  • You have to have VU server running.
  • From the VU Server GUI; Get the UID of the dial you want to update.
  • From the VU Server GUI; Get the API key you want to use for this purpose (create a new one or use existing one).

In order to update the dial, we need to make a HTTP request to the VU server.

Let's say we want to set the dial with the UID 3E0075000650564139323920 to 50% using API key cTpAWYuRpA2zx75Yh961Cg

We can make a simple GET request using wget (or curl if you prefer):

wget -O- -q "http://localhost:5340/api/v0/dial/3E0075000650564139323920/set?value=50&key=cTpAWYuRpA2zx75Yh961C" ; echo

You can use pipe redirects in your terminal to redirect output of applications to VU dials.

Let's say we use following command to retrieve CPU usage on our Ubuntu machine

echo $[100-$(vmstat 1 2|tail -1|awk '{print $15}')]

This command will output an integer that represents CPU usage in percentage. We can then forward this information to VU server using pipe redirects

echo $[100-$(vmstat 1 2|tail -1|awk '{print $15}')] | xargs -I{} wget -O- -q "http://localhost:5340/api/v0/dial/3E0075000650564139323920/set?value={}&key=cTpAWYuRpA2zx75Yh961C"; echo

Please keep in mind that this is a very "simple" example (and yet looks somewhat complicated), but the main idea is that you can easily redirect output of any application on your system and send it to VU Server to have it displayed on your VU1 dials.

Ideally you would not run these commands manually but instead have a script/service/cron that updates your dials periodically.