Sex, 2009-04-10 às 10:11 -0400, john cooper escreveu:
> Jorge Pinto aka Casainho wrote:
> > Hello :-)
> >
> > As I said before, we are working on Lyre project, a Free/Open hardware
> > audio player
> > (DAP) and recorder, for use with RockBox firmware.
> >
> > We will probably use an SD Card for hold the audio files and for easy
> > the life of users for sharing music (I mean music with Creative Commons
> > license and the recorded by users).
> >
> > My question is: is the USB really need if we have an SD Card? would
> > users still miss the USB?
>
> Ok, here is where the issue of 1-bit SPI mode vs. 4-bit SD
> mode may become an issue. SPI is fine for pulling data from
> the card at compressed audio stream rates. But if you are
> using it to transfer bulk data as in the case of
> down/uploading from a host PC, it could be unacceptably slow.
>
> And unless you have an SPI controller shuffling data to/from
> the card at 25Mb/s is going to be a challenge.

Ok. Well, we can have a DMA channel for transfer each sector (512
bytes), at 25MHz.

> > 2nd question: if we need to use USB, does we need to pay royalties for
> > use it?
>
> Again IANAL but have a look here:
>
> http://www.usb.org/developers/logo_license
>
> The issues are whether you want to use the USB logos
> and more importantly getting a VID. I have no idea
> what degrees of maneuvering freedom exist around not
> paying for a unique VID.

How does Rockbox do? from where come from the Rockbox firmware USB VID?
Received on 2009-04-10