AVR-Chat

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