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?
