Problem phenomenon
| module | lsusb results | dev |
|---|---|---|
| IMU USB Serial Port Module | 10c4:ea60 Silicon Labs CP210x UART Bridge | /dev/ttyUSB0 |
| Chassis USB Serial Port Module | 10c4:ea60 Silicon Labs CP210x UART Bridge | /dev/ttyUSB1 |
1. When the device is restarted, there is a low probability that the ttyUSB{0,1} serial numbers of the two modules are exchanged, causing the program to fail to run after the system is restarted.
2. Think of distinguishing modules by USB pid:vid, but the two modules have the same uid:pid
Think of it
Distinguishing modules through finer-grained udev ATTRS attributes
Debugging and verification
Query imu usb module properties
1. Insert the IMU usb serial port module, add /sys/bus/usb/drivers/usb/7-1.1
2. Query usb ATTR attribute
udevadm info -a -p /sys/bus/usb/drivers/usb/7-1.1/
looking at device '/devices/platform/usbdrd3_0/fc000000.usb/xhci-hcd.9.auto/usb7/7-1/7-1.1':
KERNEL=="7-1.1"
SUBSYSTEM=="usb"
DRIVER=="usb"
ATTR{devspec}=="(null)"
ATTR{authorized}=="1"
ATTR{speed}=="12"
ATTR{quirks}=="0x0"
ATTR{configuration}==""
ATTR{devpath}=="1.1"
ATTR{bNumConfigurations}=="1"
ATTR{ltm_capable}=="no"
ATTR{bMaxPower}=="100mA"
ATTR{bDeviceSubClass}=="00"
ATTR{rx_lanes}=="1"
ATTR{idVendor}=="10c4"
ATTR{bmAttributes}=="80"
ATTR{maxchild}=="0"
ATTR{bNumInterfaces}==" 1"
ATTR{manufacturer}=="Silicon Labs"
ATTR{busnum}=="7"
ATTR{idProduct}=="ea60"
ATTR{bMaxPacketSize0}=="64"
ATTR{removable}=="unknown"
ATTR{product}=="CP2102 USB to UART Bridge Controller"
ATTR{urbnum}=="307803"
ATTR{bDeviceProtocol}=="00"
ATTR{bConfigurationValue}=="1"
ATTR{bDeviceClass}=="00"
ATTR{avoid_reset_quirk}=="0"
ATTR{tx_lanes}=="1"
ATTR{bcdDevice}=="0100"
ATTR{devnum}=="40"
ATTR{version}=="1.10"
ATTR{serial}=="0001"
Query chassis usb module properties
1. Insert the IMU usb serial port module, add /sys/bus/usb/drivers/usb/7-1.2
2. Query usb ATTR attribute
udevadm info -a -p /sys/bus/usb/drivers/usb/7-1.2/
looking at device '/devices/platform/usbdrd3_0/fc000000.usb/xhci-hcd.9.auto/usb7/7-1/7-1.2':
KERNEL=="7-1.2"
SUBSYSTEM=="usb"
DRIVER=="usb"
ATTR{urbnum}=="127201"
ATTR{maxchild}=="0"
ATTR{authorized}=="1"
ATTR{bDeviceSubClass}=="00"
ATTR{manufacturer}=="Silicon Labs"
ATTR{bDeviceClass}=="00"
ATTR{busnum}=="7"
ATTR{bDeviceProtocol}=="00"
ATTR{bConfigurationValue}=="1"
ATTR{bmAttributes}=="80"
ATTR{quirks}=="0x0"
ATTR{ltm_capable}=="no"
ATTR{version}==" 2.00"
ATTR{bMaxPower}=="100mA"
ATTR{removable}=="unknown"
ATTR{rx_lanes}=="1"
ATTR{tx_lanes}=="1"
ATTR{devnum}=="38"
ATTR{idVendor}=="10c4"
ATTR{serial}=="6275b2d5040dec11ab81dccebd930c07"
ATTR{product}=="CP2102N USB to UART Bridge Controller"
ATTR{avoid_reset_quirk}=="0"
ATTR{bNumInterfaces}==" 1"
ATTR{bMaxPacketSize0}=="64"
ATTR{configuration}==""
ATTR{bcdDevice}=="0100"
ATTR{speed}=="12"
ATTR{devspec}=="(null)"
ATTR{idProduct}=="ea60"
ATTR{devpath}=="1.2"
ATTR{bNumConfigurations}=="1"
Compare attribute differences
#chassis
-- ATTR{product}=="CP2102 USB to UART Bridge Controller"
-- ATTR{devpath}==" 1.2"
#imu
+ + ATTR{version}==" 2.00"
+ + ATTR{product}=="CP2102N USB to UART Bridge Controller"
Writing rules
/etc/udev/rules.d/900-myself-dev.rules
KERNEL=="ttyUSB*", ACTION=="add", ATTRS{idVendor}=="10c4", ATTRS{idProduct}=="ea60", ATTRS{version} ==" 2.00",ATTRS{product}=="CP2102N USB to UART Bridge Controller", MODE:="0666", SYMLINK + ="ttyImu"
KERNEL=="ttyUSB*", ACTION=="add", ATTRS{idVendor}=="10c4", ATTRS{idProduct}=="ea60", ATTRS{version}==\ " 1.10",ATTRS{product}=="CP2102 USB to UART Bridge Controller", MODE:="0666", SYMLINK + ="ttyChaisses"
Verify Verification:
Plugging and unplugging the USB does not take effect
Debug udev method
Method 1: Unplug the USB, open udev log
udevadm control --log-priority=debug #Set log level journalctl -f #Query udev service log
May 15 15:56:15 orangepi5 systemd-udevd[21823]: ttyUSB0: Processing device (SEQNUM=5744, ACTION=bind)
May 15 15:56:15 orangepi5 systemd-udevd[21823]: ttyUSB0: /etc/udev/rules.d/900-myself-dev.rules:3 MODE 0666
May 15 15:56:15 orangepi5 systemd-udevd[21823]: ttyUSB0: /etc/udev/rules.d/900-myself-dev.rules:3 RUN ‘/etc/ruichi/udev-test.sh’
May 15 15:56:15 orangepi5 systemd-udevd[21823]: ttyUSB0: Running command “/etc/myself/udev-test.sh”
May 15 15:56:15 orangepi5 systemd-udevd[21823]: ttyUSB0: Starting ‘/etc/myself/udev-test.sh’
It can be seen from the udev log that the 900-myself-dev.rules rule is triggered and the corresponding /dev/ttyImu device is enumerated
Method 2: udevadm test simulation
udevadm test /sys/bus/usb/drivers/usb/7-1.2/
Reading rules file: /etc/udev/rules.d/900-ruichi-dev.rules
Invalid inotify descriptor.
DEVPATH=/devices/platform/usbdrd3_0/fc000000.usb/xhci-hcd.9.auto/usb7/7-1/7-1.2
DEVNAME=/dev/bus/usb/007/038
DEVTYPE=usb_device
DRIVER=usb
PRODUCT=10c4/ea60/100
TYPE=0/0/0
BUSNUM=007
DEVNUM=038
MAJOR=189
MINOR=805
ACTION=add
SUBSYSTEM=usb
ID_VENDOR=Silicon_Labs
ID_VENDOR_ENC=Silicon\x20Labs
ID_VENDOR_ID=10c4
ID_MODEL=CP2102N_USB_to_UART_Bridge_Controller
ID_MODEL_ENC=CP2102N\x20USB\x20to\x20UART\x20Bridge\x20Controller
ID_MODEL_ID=ea60
ID_REVISION=0100
ID_SERIAL=Silicon_Labs_CP2102N_USB_to_UART_Bridge_Controller_6275b2d5040dec11ab81dccebd930c07
ID_SERIAL_SHORT=6275b2d5040dec11ab81dccebd930c07
ID_BUS=usb
ID_USB_INTERFACES=:ff0000:
ID_VENDOR_FROM_DATABASE=Silicon Labs
ID_MODEL_FROM_DATABASE=CP210x UART Bridge
REALTEK_NIC_MODE=1
USEC_INITIALIZED=9888901551
Unload module index
Unloaded link configuration context.
Result:
It doesn’t take effect, I don’t know if it is a path, and there is a problem with the command usage.
Solution for rules not taking effect: restart udev
udevadm control --reload-rules #Reload rules systemctl restart udev.service #restart udev service
result:
Enumeration succeeded
/dev/ttyUSB0 /dev/ttyChaisses
/dev/ttyUSB1 /dev/ttyImu
Update record
1. Update the rules rules
1.1 ACTION==“bind” – ACTION==“add”
1.2 Remove ACTION==”bind”, and the actual measurement will also take effect