[time-nuts] LTE-Lite

[Hal Murray]

kb8tq at n1k.org said:
> The “new chip ID, new com port” thing is pretty typical for the FTDI
> drivers. If you plug the old LTE back in there’s a good chance it will come
> back up as COMM 5. Usually they are pretty good about only adding ports for
> devices they have not seen before. 

Most/some of the FTDI usb to serial chips have a serial number.  I don't know 
how it works on Windows, but on Linux, you can use the udev rules to make an 
alias so your software can refer to something with a filename like /dev/LITE 
rather than /dev/ttyUSB2.  It works no matter which slot you plug it into 
and/or still works after it gets unplugged and reconnected.

lsusb -v will show things like:
  idVendor           0x0403 Future Technology Devices International, Ltd
  idProduct          0x6001 FT232 USB-Serial (UART) IC
  bcdDevice            6.00
  iManufacturer           1 FTDI
  iProduct                2 FT232R USB UART
  iSerial                 3 A102GX1N

/var/log/messages or /var/log/syslog will contain something like:
Nov 28 15:12:00 deb kernel: [1392082.791230] usb 3-3: Product: FT232R USB UART
Nov 28 15:12:00 deb kernel: [1392082.791235] usb 3-3: Manufacturer: FTDI
Nov 28 15:12:00 deb kernel: [1392082.791240] usb 3-3: SerialNumber: A102GX1N
Nov 28 15:12:00 deb kernel: [1392082.799337] ftdi_sio 3-3:1.0: FTDI USB 
Serial Device converter detected
Nov 28 15:12:00 deb kernel: [1392082.799447] usb 3-3: Detected FT232RL
...
Nov 28 15:12:00 deb kernel: [1392082.805436] usb 3-3: FTDI USB Serial Device 
converter now attached to ttyUSB3


This is what I put in /etc/udev/rules.d/35-hgm.rules

# LTE LITE Eval Board
KERNEL=="ttyUSB*", ATTRS{serial}=="A102GX1N", MODE="0666", SYMLINK+="LITE"


I use the same approach with my Rigol scope and Prologic USB-GPIB.


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