first thing are you using the correct miner cgminer 4.9.0? command line should be like this cgminer.exe -o http://127.0.0.1:8332 -u fred -p password --au3-freq 225 --au3-volt 800 --btc-address
I'm using the last cgminer with minera. I don't really know where to check those command lines, I'm not really familiar with console commands and Pi stuff, just getting started here
I'm not using a USB hub, my U3 is directly plugged into the Pi. Is it a problem? Not enough amps?