AVR-Chat

Thanks Michael, I have often wanted to try using these cards myself,
but could never find any useful information. Cheers Hein B



--- In AVR-Chat@yahoogroups.com, Michael De Nil <michael@...> wrote:
>
> mohsen_zamani1364 wrote:
> 
> >i have problem with mini sd card. The problem is that i dont know how 
> >can we send command to sd card  please guide me .
> >
> hi mohsen,
> 
> you can communicate in two ways with a (mini) sd-card:
> - through spi
> - through the sd-protocol
> 
> although the sd-protocol is faster (it uses 4 wires to communicate
> instead of 1), the spi-interface will be preferable in case you will be
> working on an avr uc. an spi-interface is available on (all?) atmega's
> and can run on half of the clock rate. when you want the use the
> sd-protocol, you will need to toggle all lines manually, which will
> probably be slower than when using the built-in spi functionality.
> 
> for more information, i would like you to refer to:
> - wikipedia (http://en.wikipedia.org/wiki/Secure_Digital)
> - sandisk sd card product manual
> (http://www.cs.ucr.edu/~amitra/sdcard/ProdManualSDCardv1.9.pdf)
> - efsl, an embedded file system library which supports fat12/16/32 and
> has a hardware layer for sd/mmc - spi for avr. it also contains a manual
> containing a "how to get started"-section for avr which will explain you
> step by step how to connect an sd-card to you avr and how to use the
> library. (http://www.sf.net/projects/efsl)
> 
> 
> good luck!
> 
> michael
>