Trying CGMiner now. Getting a "Failed to initiate device" error. It recognizes the devices.
Using ./cgminer -o stratum+tcp://peercoin.ecoining.com:3336/ -u blackbird.2 -p 12345 --compac-freq 150
I would like to help, but I have not seen that error specifically. Can I get a little more info about your setup? What OS, How are you powering, did you rebuild cgminer,etc? Maybe get a little more cgminer output?
I posted a question for you on another thread do you know if I can run older U2's in the same instance of cgminer or can I only stick to the compacs id like to fill the rest of the hub with my older U2's and ahve only 1 pi 2 running them all

I don't know if they will detect correctly, as the icarus driver specifically can detect anything with approximately the correct chips. You can try, you'd need top build with --enable-icarus and --enable-gekko.
Novak can you provide a diagram showing the voltage adjustment position in relation to voltage I use the flat surface as a guide and with it directly flush with USB port I have been able to get to 250 mhz or so no HW errors I dont have a volt meter handy to test what voltage that brings me up to
Here you go:

--
novak