I've successfully compiled the latest Teensy 3.1 branch of Teacup_Firmware as per instructions on the Reprap wiki

I'm using Ubuntu Linux 14.10.

No more errors in compile using Paul's most recent teensyduino 1.21 I've associated it with Arduino IDE v1.0.6, but am actually compiling with Teacup_Firmware's Makefile using the ARM toolchain supplied with Teensyduino at the commandline.

As I said, It compiles fine, and the HEX file uploads to the Teensy, but I do not get /dev/ttyACM0 on Teensy reboot. If I replace the HEX with another sketch I compiled in the Arduino IDE (any thing) I get /dev/ttyACM0 to show up.

I know about the need to initialize the virtual serial over USB by sending a string out from the Teensy. I do not see this happening in Teacup_Firmware, however I know others have been able to compile and use it successfully on the Teensy. I'm at a loss as to where to start looking.

Any guidance would be appreciated.