I'm running 30 on a Pi.
I have 3 sabrent 13 port hubs daisy chained. CG and scripta are only seeing 12 miners.
Thoughts??
-Bobby
Pi can only see 2 levels of USB hubs. A 13-port hub has another hub inside, so that's two levels. It means you can run 26 miners by connecting a 13-port hub to each of the two USB ports on the Pi.
Then you can try connecting another hub to one of the first two hubs and gain five more ports, however you need to make sure that you connect it to the first level on the first hub (trial an error method works, or see below) and you'll only be able to see 6 of the 13 ports. Yeah, it is that confusing. Use "lsusb -t" to see how this all looks like. If you have a Windows PC you can use this: http://www.uwe-sieber.de/usbtreeview_e.html to test out how to daisy-chain the hubs and the connect them the same way to the Pi.
(edit: added link to USB Tree View).