Udev-Rules

How to identify the device (Arduino)

• Unplug all other USB devices that are similar to the arduino or that are not in use.

• You can leave your Keyboard and mouse plugged in.

Make sure you are not using a USB hub to connect the Arduino or device.

Run the command:

ls -l /dev/tty*

The result should look like this:

crw-rw---- 1 root dialout   4, 69 Feb 19 08:07 /dev/ttyS5
crw-rw---- 1 root dialout   4, 70 Feb 19 08:07 /dev/ttyS6
crw-rw---- 1 root dialout   4, 71 Feb 19 08:07 /dev/ttyS7
crw-rw---- 1 root dialout   4, 72 Feb 19 08:07 /dev/ttyS8
crw-rw---- 1 root dialout   4, 73 Feb 19 08:07 /dev/ttyS9
crw-rw---- 1 root plugdev 188,  0 Feb 20 19:02 /dev/ttyUSB0 

• If you see a /dev/ttyUSB followed by a number or a /dev/ttyACM followed by a number, that is your device. In this case my was /dev/ttyUSB0

How to identify the Vendor & Product ID

Run the command:

lsusb

The result should look like this:

Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub 
Bus 001 Device 027: ID 1a86:7523 QinHeng Electronics HL-340 USB-Serial adapter 
Bus 001 Device 003: ID 062a:5918 Creative Labs 
Bus 001 Device 006: ID 8087:0aaa Intel Corp. 
Bus 001 Device 022: ID 413c:2113 Dell Computer Corp. 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

This process is the hardest part as you have to identify which of the items on the list are your device.

• If you are using a genuine Arduino it will be listed as such but if you have a clone or cheapy version you will see a 340 series usb serial adapter(CH340, HL340) or you may see nothing listed after the numbers.

• If you still cant tell then just unplug the device, run the command, replug and run again and you will identify the missing device that way.

• In my case it was Bus 001 Device 027: ID 1a86:7523 QinHeng Electronics HL-340 USB-Serial adapter

• Now from this output we know we locate the vendor & product ID.

• For the device listed above the vendor ID is 1a86 and the product ID is 7523.

• Save those two numbers somewhere.

Creating the rule

Run the command:

cd /etc/udev/rules.d && ls

• This will take you to the rules directory and list all the available files.

The output should look something like this:

70-snap.arduino.rules               70-snap.qalculate.rules
70-snap.flameshot.rules             70-snap.snapd.rules
70-snap.gnome-characters.rules      70-snap.spotify.rules
70-snap.gnome-logs.rules            70-snap.vlc.rules

Now follow the naming convention of the files in this case(70-XXXXX.rules).

Run the command:

sudo gedit 70-new-arduino.rules

• Put in your password and a new file will appear.

In the new file place the following contents and replace the vendor and product ID's:

SUBSYSTEM=="tty", GROUP="plugdev". MODE="0660"

SUBSYSTEMS=="usb", ATTRS{idProduct}=="7523", ATTRS{idVendor}=="1a86", SYMLINK+="arduino"

You can add as many devices as you like, then save & exit the file.

Run the command:

sudo udevadm control --reload-rules && sudo service udev restart && sudo udevadm trigger

Once this is completed we have the symlink and better permissions for the arduino or device.

Restart the computer and proceed to the final steps.

Run the command:

ls -l /dev/arduino /dev/ttyUSB0

The result should look like this:

lrwxrwxrwx 1 root root        15 Feb 20 19:02 /dev/arduino -> bus/usb/001/027
crw-rw---- 1 root plugdev 188, 0 Feb 20 19:02 /dev/ttyUSB0

Finally unplug and replug the device and run the command again and the device should come up.

You can now use dev/ttyUSB0 for whatever your want without worrying about the device flip flopping.