USB reference

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Revision as of 06:33, 18 March 2009 by Gruso (talk | contribs) (What does “OTG” mean?)
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Readme First!

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USB FAQ

How many USB ports does Pandora have?

Pandora has two USB ports:

  • 1x USB 2.0 host port (Standard “USB A” socket)
  • 1x USB 1.1/2.0 OTG port (“Mini AB” socket)

What does “host port” mean?

A USB host port “hosts” any device that you plug in, just like the USB ports on your computer. Pandora’s full size USB A port can host USB 2.0 devices, and provide up to 500mA (the maximum allowed according to USB standards).

What does “OTG” mean?

OTG stands for On The Go. USB OTG ports can operate in two different modes. It can connect Pandora to a computer for charging & data transfer, or with the use of an OTG adaptor, it can act as a host port for USB 1.1 and USB 2.0 devices. This port can supply a maximum of 100mA in host mode.

What’s all this stuff about USB 1.1 and USB 2.0? Isn’t USB, uh, universal?

The USB 2.0 protocol is not backwards compatible with USB 1.1. Most USB ports (eg. on your computer’s motherboard, in USB hubs) actually contain two chips to allow universal compatibility – one for USB 1.1, and one for USB 2.0.

Pandora’s USB A host port does not contain this second chip. Only USB 2.0 devices bearing the “USB HIGH SPEED” logo can be plugged directly into this port. However, USB 1.1 devices can be connected to this port through a USB hub, provided the hub bears the “USB HIGH SPEED” logo.

Pandora’s USB OTG (Mini AB) port is fully compatible with both USB 1.1 and USB 2.0, allowing it to host either type of device.

So which devices are USB 1.1, and which ones are USB 2.0?

There are no rules, and with so many manufacturers making so many different devices, it's impossible to give a definitive answer. As a general guide though:

  • Common USB 1.1 devices: Keyboards, mice, webcams, headsets, older USB devices.
  • Common USB 2.0 devices: Cameras, PMPs, HDDs, hubs, card readers, thumb drives.

Just to reiterate, this is a very general guide. It’s not based on any rules, it’s just a rough representation of what’s out there in the wild. Devices like HSDPA modems and GPS units could fall into either category. The only reliable indication of true USB 2.0 compatibility is the “USB HIGH SPEED” logo.

Ack, USB used to be simple. What can I actually connect to Pandora?

Pandora's USB ports can be used in three ways:

Pandora as USB slave

[in progress]

Hosting USB devices

[in progress]

OTG host mode

[in progress]