i got same trouble cannot found a AUC2 controller for my avalon 6 =( ive try to contact canaan they asnwer me whit a auto-reply we are out of stock of everything lol i just order on ebay this :http://www.ebay.com/itm/USB-to-I2C-IIC-TWI-SMBUS-master-Converter-4pin-ADC-Decoder-Program-24xx-EEPROM/281920556383?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649 it looking good but if i check the IIC on the main board on avalon 6 it like that :

https://en.bitcoin.it/w/images/en/b/b8/IIC_Link_Avalon6.png


why 2 Ground?? on the Usb to I2C ive oder it ground,VCC,SDA and SCL maybe it the diffence between AUC2 and AUC3 will see when i receive it and try to make it work something like jumping the second ground!