There have been some problems trying to use the ButterFly serial port as described in the Atmel documentation if using USB to Serial Adapter.
One problem is that these drivers often install their "virtual" serial ports above COM4 and the "AVR Prog" utility in the Studio-4 software will only recognize COM1 to COM4. The solution is to manually reconfigure your Windoze so that the "fake" serial port is in the range of COM1 to COM4.
The second problem usually occurs with USB converters that do not have a separate power-supply. The Butterfly does not use an RS232 level conversion chip, but instead "borrows" power from the incoming singnals to achieve the higher RS232 levels going out. Some of the USB-to-RS232 converteres do not provide enough power for the ButterFly circuitry to do this. The fix here is to add a power-supply if possible, to the USB Converter.
One problem is that these drivers often install their "virtual" serial ports above COM4 and the "AVR Prog" utility in the Studio-4 software will only recognize COM1 to COM4. The solution is to manually reconfigure your Windoze so that the "fake" serial port is in the range of COM1 to COM4.
The second problem usually occurs with USB converters that do not have a separate power-supply. The Butterfly does not use an RS232 level conversion chip, but instead "borrows" power from the incoming singnals to achieve the higher RS232 levels going out. Some of the USB-to-RS232 converteres do not provide enough power for the ButterFly circuitry to do this. The fix here is to add a power-supply if possible, to the USB Converter.