How would I get more usb ports on a Raspberry Pi? 2 just isn't enough.
The obvious answer is a hub, however I have tried many and none work.
My friend said that most hubs drive power back to the pi, which it doesn't understand. He bought a hub specially designed for Raspberry Pi, and it works fine on his but not on mine.
Is this because he has a more recent OS version than I do? We both are running Raspbian, but he has a later version than me.
You should make sure that the USB hub is:
(a) a powered hub,
(b) for USB 2.0, and
(c) preferably verified on this wiki page with a list of verified powered USB hubs for the Raspberry Pi.
I also did a bit of googling and found PiHub, which is one that has been specially designed to be compatible with the Pi.
There are some hubs that are 'problem hubs' due to the fact that they leak power back to the pi. This can be fixed my modifying the cable by either shorting the +5V pin #1 or putting a piece of tape/glue over the connector. Otherwise, ysim's answer is the way to go.
