thanks for the post.. i'm using an avr32 bit chip with USB embedded in it. When i connect to linux (ubuntu 12.10 64bit), the device shows up as ttyACM0 and the PC tries sending AT+ commands for about a minute after my device connects. quite annoying because i'm doing development work and the device is unavailable during this routine. do you know if it is possible to disable this mount routine from the PC? or better yet is it possible to change my device configuration so it shows up as ttyUSB?

The article explains precisely why this would not be possible for it to show as ttyUSB. Check the Ubuntu help center and forums if Ubuntu insists on talking to your device.

I'm not sure why you are saying that it is not possible for the device to announce itself as ttyUSB? I can set how the usb announces itself using various registers on the device. there is example code that changes my microcontroller from cdc to HID or mass storage etc.. Unfortunately nothing that seems to conform to the ttyUSB spec. When i force this driver my device enumerates successfully as ttyUSB one time, but not again until i reboot. i get the following error message:

[878887.203226] usbserial_generic 5-2:1.0: Generic device with no bulk out, not allowed.

i'm going to spend some more time looking for usbserial documentation but any constructive advice would be welcome! thanks again