It seems that to activate the installed DFU bootloader, a power-on reset is required. A software generated reset or external reset won't do. I have to yank the USB cable out of the PC and plug it back in while holding down switch 0. What if I only had one hand? I would have to yank out the cable and replace it with my teeth, or press switch 0 with my nose.
Speaking of external reset, there is no reset push button on the board. Am I the only one who wants such a thing on a development board?
The JTAG 10 pin header can be used for PDI, but the PDI data signal is connected to the JTAG TDO pin. That means I either have to cut a "strap" on the board or change the JTAG enable fuse bit in order to use PDI. I wonder why the otherwise unused pin 8 of the JTAG header wasn't used for this, like was done on the 128A1 Xplain board.