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ID-s for USB-serial adapters

Unique semi-human-friendly IDs for USB-UART adapters (e.g. FTDI, CP) generated from serial numbers

This repository holds scripts to generate unique serial numbers for dual-port FTDI chips commonly used as JTAG programmers and TTL level UART adapters. The serial numbers are stored in the EEPROM of each device and they show up as a symlinks in the /dev directory. No more detective work to figure out which /dev/ttyUSB? device belongs to your USB-serial adapter!

Example: if your ESP Prog board has been flashed with serial EP012 then its two ports would always show up as symlinks /dev/EP012_uart and /dev/EP012_jtag regardless of the order in which USB serial devices were plugged into the computer.

Install prerequisites

Most devices have factory-issued serial numbers, e.g. "FTYI1XTW". To use those, you don't need anything extra - just follow the instructions in next section.

To program FTDI devices which don't have factory-issued serial numbers, you need the ftdi_eeprom utility:

$ sudo apt install ftdi-eeprom

To see the serial number and other attributes of the device, plug it in and query using lsusb, e.g.:

lsusb -d 0403:6015 -v

Install the udev rules for device names

To install udev rules which create the symlink with device name, link the following files to /etc/udev/rules.d and restart udev:

$ cd unique_udev_symlinks
$ sudo find "$(pwd)" -name "*.rules" -exec ln -s "{}" /etc/udev/rules.d/ \;
$ sudo systemctl restart udev

Now plug in your USB-serial adapter (which has a unique serial number assigned to it) and see nice names like /dev/EP001_uart or /dev/EWK001_jtag show up as symlinks to the correct /dev/ttyUSB? devices.

Flash a new FTDI device with a unique serial number

Before the names appear, the FTDI device must have a unique serial number programmed into it (the factory default for some ESP devices is a blank EEPROM, which we need to program ourselves). This is easy enough.

  • Open the file ESP-Prog/eeprom_ft2232h_ESP-Prog.conf (if using an ESP Prog board) or ESP-WROVER-KIT/eeprom_ft2232h_ESP-WROVER-KIT.conf (if using an ESP WROVER Kit board)
  • Increment the number in field serial by one. Save and close, commit the file to git and push.
  • Follow instructions in the header of same file to flash the EEPROM
  • Reconnect the board, watch the new symlink appear in /dev
  • Did you remember to commit the file to git and push?