Assign symbolic link for auto-mounting USB devices by udev

Introduction

Linux kernel usually just assigns unpredictable device names. We would need udev rule to make it predictable. In technical, it can generate custom & specifiy symblic links, based on Vid, Pid, plugged-in USB port number...etc.

In this document, we will describe our rules and define the naming convensions.

The XU3/XU4 diagram and USB ports

The ODROID-XU3 USB2.0 sockets (A-D) 

The ODROID-XU4 USB3.0 sockets (A-B) 

Port Assignments

The ODROID-XU3 USB2.0 sockets (A-D)

The ODROID-XU4 USB3.0 sockets (A-B)

The Symbolic links design

#Andbot 0

10-port USB Hub

#Andbot 1.1

7-port USB Hub

USBHub-7p-black.jpg

Using 2 7-port USB Hub

USBHub-7p-A.jpg

Check out the Ardurino Mega2560 board PID/VID, and USB connect sorcket infomation (connect to socket A)

Andbot no.1

USBHub-7p-A11.jpg

#Andbot 1.2

7-port USB Hub

USBHub-7p-andbot12.jpg

#Rogby

7-port USB Hub

USBHub-7p-rugby.jpg

Check out the Ardurino Mega2560 board PID/VID, and USB connect sorcket infomation (connect to socket B)

This is the example for 10-port USB hub case

$ udevadm info -a -n ttyACM0

The follows information are we need.

  looking at device '/devices/12110000.usb/usb1/1-1/1-1.2/1-1.2:1.0/tty/ttyACM0':
    ...
    KERNEL=="ttyACM0"
    ...
    ATTRS{devpath}=="1.2"
    ATTRS{idVendor}=="2341"
    ATTRS{idProduct}=="0042"
    ...

Check out the Ardurino Mega2560 board PID/VID, and USB connect sorcket infomation (connect to port1 of the 10-port USB hub which had connected to socket A)

  looking at device '/devices/12110000.usb/usb1/1-1/1-1.2/1-1.2.4/1-1.2.4:1.0/tty/ttyACM0':
    ...
    KERNEL=="ttyACM0"
    ...
    ATTRS{devpath}=="1.2.4"
    ATTRS{idVendor}=="2341"
    ATTRS{idProduct}=="0042"

Single MEGA2560 in base (connected to port1 of the USB hub)

It will be assigned to mega_base0 udev rule will match VID=2341, PID=0042, and Port number 1.2.4

Two MEGA2560 in Left Arm

It will be assigned to mega_arm_left0 udev rule will match VID=2341, PID=0042, and Port number 1.2.3

It will be assigned to mega_arm_left1 udev rule will match VID=2341, PID=0042, and Port number 1.2.1.1

Two MEGA2560 in right Arm

It will be assigned to mega_arm_right0 udev rule will match VID=2341, PID=0042, and Port number 1.2.1.4

It will be assigned to mega_arm_right1 udev rule will match VID=2341, PID=0042, and Port number 1.2.1.3

The other ports of the USB hub (Reserved)

mega_in_hub6 udev rule will match VID=2341, PID=0042, and Port number 1.2.1.2

mega_in_hub7 udev rule will match VID=2341, PID=0042, and Port number 1.2.2.4

mega_in_hub8 udev rule will match VID=2341, PID=0042, and Port number 1.2.2.3

mega_in_hub9 udev rule will match VID=2341, PID=0042, and Port number 1.2.2.2

create a udev rule file in /etc/udev/rules.d/;

/etc/udev/rules.d/99-mega2560-usb_hub_10port.rules

KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.4", SYMLINK+="mega_base0"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.3", SYMLINK+="mega_arm_left0"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.1", SYMLINK+="mega_arm_left1"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.4", SYMLINK+="mega_arm_right0"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.3", SYMLINK+="mega_arm_right1"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.2", SYMLINK+="mega_in_hub6"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.2.4", SYMLINK+="mega_in_hub7"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.2.3", SYMLINK+="mega_in_hub8"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.2.2", SYMLINK+="mega_in_hub9"

/etc/udev/rules.d/99-mega2560-usb_hub.rules

/etc/udev/rules.d/99-mega2560-usb_hub_7port.rules

KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.4", SYMLINK+="mega_base0"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.3", SYMLINK+="mega_arm_left0"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.4", SYMLINK+="mega_arm_left1"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.3", SYMLINK+="mega_arm_right0"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.2", SYMLINK+="mega_arm_right1"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.2", SYMLINK+="mega_in_hub6"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.1, SYMLINK+="mega_in_hub7"

##Andbot #1## /etc/udev/rules.d/99-mega2560-usb_hub_7port-a.rules

KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.4", SYMLINK+="mega_base"
KERNEL=="ttyUSB*", ATTRS{idProduct}=="2303", ATTRS{idVendor}=="067b", ATTRS{devpath}=="1.2.1.3", SYMLINK+="xv11"
KERNEL=="ttyUSB*", ATTRS{idProduct}=="2303", ATTRS{idVendor}=="067b", ATTRS{devpath}=="1.2.4", SYMLINK+="gyro"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.2", SYMLINK+="mega_head"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.2.1.4", SYMLINK+="mega_arm_left0"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.2.1.3", SYMLINK+="mega_arm_left1"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.2.4", SYMLINK+="mega_arm_right0"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.2.3", SYMLINK+="mega_arm_right1"

The udev rule makes those Symbolic links (mega_)to ttyACM which corresponding to each mounted Mega2560 boards in USB hub. The udev rule makes those Symbolic links (xv11)to ttyUSB* which corresponding to USB hub port 1.2.1.3 The udev rule makes those Symbolic links (gryo)to ttyUSB* which corresponding to USB hub port 1.2.4

##Andbot #1.1 Machine-No1## /etc/udev/rules.d/99-mega2560-usb_hub_7port-a11.rules

KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.4", SYMLINK+="mega_base"
KERNEL=="ttyUSB*", ATTRS{idProduct}=="ea60", ATTRS{idVendor}=="10c4", ATTRS{devpath}=="1.2.1.3", SYMLINK+="rplidar"
# for XV11 (blue dongle) KERNEL=="ttyUSB*", ATTRS{idProduct}=="2303", ATTRS{idVendor}=="067b", ATTRS{devpath}=="1.2.4", SYMLINK+="gyro"
KERNEL=="ttyUSB*", ATTRS{idProduct}=="6001", ATTRS{idVendor}=="0403", ATTRS{devpath}=="1.2.4", SYMLINK+="gyro"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.2", SYMLINK+="mega_head"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.2", SYMLINK+="mega_arm"

##Andbot #1.2## /etc/udev/rules.d/99-mega2560-usb_hub_7port-a12.rules

KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.4", SYMLINK+="mega_arm"
KERNEL=="ttyUSB*", ATTRS{idProduct}=="6001", ATTRS{idVendor}=="0403", ATTRS{devpath}=="1.2.1.3", SYMLINK+="xv11"
KERNEL=="ttyUSB*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.4", SYMLINK+="mega_base"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.2.1.2", SYMLINK+="mega_head"
KERNEL=="ttyACM*", ATTRS{idProduct}=="2303", ATTRS{idVendor}=="067b", ATTRS{devpath}=="1.2.1.1", SYMLINK+="gyro"

##Rugby## /etc/udev/rules.d/99-rugby.rules

KERNEL=="ttyACM*", ATTRS{idProduct}=="0042", ATTRS{idVendor}=="2341", ATTRS{devpath}=="1.1.1.4", SYMLINK+="mega_base"
KERNEL=="ttyACM*", ATTRS{idProduct}=="0608", ATTRS{idVendor}=="05e3", ATTRS{devpath}=="1.1.1", SYMLINK+="tablet"

KERNEL=="ttyUSB*", ATTRS{idProduct}=="ea60", ATTRS{idVendor}=="10c4", ATTRS{devpath}=="1.1.1.2", SYMLINK+="rplidar"
KERNEL=="ttyUSB*", ATTRS{idProduct}=="6001", ATTRS{idVendor}=="0403", ATTRS{devpath}=="1.1.1.3", SYMLINK+="gyro"

Please reference picture of the Rogby's USB hub connecting design.(USBHub-7p-rugby.jpg)

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References

ODROID-XU3 EVM board (http://www.hardkernel.com/main/products/prdt_info.php?g_code=G140448267127)

Adurino Mega2560 boards (https://www.arduino.cc/en/Main/ArduinoBoardMega2560)

udev (https://www.kernel.org/pub/linux/utils/kernel/hotplug/udev/udev.html)