Friday, January 18, 2013

Resolving Raspberry Pi USB power problems

With only 120mW per USB port, the Raspberry Pi is woefully inadequate for most USB items, and almost inpossible to use with an unpowered Hub.

I traced the incoming +5v from the mini-usb power plug and found that the outside of the polyfuses for power are directly connected, making it pretty easy to solder some extra wiring to power the ports:

Was able to run a 4 port unpowered hub (off a 1500mW Power input) with the following:

  • 200mW USB 802.11n Wi-Fi Dongle
  • Linksys Class1 bluetooth adapter
  • Neotel Zyxel 3G/HSPA USB adapter
  • USB 100Mbps RJ45 Network Adapter
as well as a USB keyboard.

No problems whatsoever and unplugging/replugging devices off the hub as well as the keyboard did not force the unit to reset.

I also added a nifty Heatsink to the CPU/Ram BGA with some sticky thermal tape - made 1Ghz on the CPU finally possible and stable.