Rockbox General > Rockbox General Discussion

Can rockbox play from an external hard disk?

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manub686:
Hi,

It just appears natural for the firmware to be able to play from an external usb hard drive plugged into the PMP, but I'm not able to find any COTS player that would do this. All it should require is a filesystem and a USB driver on the firmware. Sandisk players do allow memory cards but not full external hdds.

The practicality can be of question, since the disk will consume a lot of power, but there are a quite a few scenario's wherever this will be very useful, for example, anywhere you would want to dock your PMP. Does rockbox have any support for this or have it in the future feature list?

GodEater:
It does not support it currently, no.

People have talked about providing USB host mode for a long time - but no-one's actually written anything to do it yet.

bluebrother:

--- Quote from: manub686 on August 28, 2009, 04:48:57 PM ---All it should require is a filesystem and a USB driver on the firmware. Sandisk players do allow memory cards but not full external hdds.
--- End quote ---

This is somewhat wrong. There's a major difference between accessing a memory card and a USB drive.

For accessing a memory card you have an internal interface to use. In case of the SD card this is usually SPI. The card itself uses a rather simple protocol. On top of that gets the filesystem. For accessing any USB device, however, you don't simply access the device via its interface (like ATA for hard disks) but need to go through the complete USB protocol, which is notably more complex than the SPI interface of an SD card. This means you need to speak the appropriate USB class, in this case USB UMS. This protocol then needs to utilize the USB hardware to talk to the device. Also, in case of USB the bus needs a master. This role is usually taken by the PC. Mobile devices like a USB drive can't take the master role. Now there are devices that can support playing the master role. This is known as USB OTG. For supporting OTG you need a chip that is capable of doing so, and you need to implement the OTG specification. This, unfortunately, is different than the "normal" USB mode Rockbox supports. Which in turn means it's lots of work. Nobody did this work yet, and judging by the time it took for getting USB slave actually work I don't think such a feature will get implemented soon, if at all.

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