I just got my ATmega32u4 today and I tried to upload a simple test program with avrdude and all I’m getting is:
avrdude: ser_open(): can’t open device “/dev/ttyACM0” Input/output error
Eavrdude: butterfly_recv(): programmer in not responding
Breakout board: http://www.sparkfun.com/products/11117
Command line: sudo avrdude -p m32u4 -P /dev/ttyACM0 -c avr109 hello-avr.out
dmesg output: cdc_acm 5-2:1.0: ttyACM0: USB ACM device
OS: Linux Mint 13.0