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File system on STR7 using SPI

tech9
Associate II
Posted on September 29, 2005 at 20:02

File system on STR7 using SPI

6 REPLIES 6
tech9
Associate II
Posted on September 12, 2005 at 18:14

I wonder if some code is available to build a file system on my STR7. I plan to use it on a SD card, driven by the SPI bus.

I know that connecting the SD card to the SPI bus is pretty straightforward, but I am puzzled when it comes to the FS...

Anyone has seen some software to build the FS?

Any suggestion is welcome.

Regards,

Tech

nopti_albe
Associate II
Posted on September 13, 2005 at 11:04

doesn't the sd card use 4 data pins? as far as i know only mmc is really 1 data pin serial =spi. I'm looking at this kind of things too... but there seems to be quite a lot of work 😉

tech9
Associate II
Posted on September 13, 2005 at 13:12

The SD card uses a data IN wire, a data OUT, a clock, and a chip select.

Looking carefully at the SPI, you get Master In Slave OUT (MISO), Master Out Slave IN, (MOSI), SCLK, and /SS. (slave select)

This fits perfectly with the previously enumerated signals.

MISO: IN, MOSI: OUT, clock: SCLK, and CS: /SS

The only remaining detail, and the biggest hurdle, is the File System. Where do I get that?

This is the main issue here: we should be able to get some sample code of how to proceed with the FS, but where?

I believe this could help a lot of people working with the STR7...

Regards,

Tech

nopti_albe
Associate II
Posted on September 25, 2005 at 11:10

http://www.sandisk.com/pdf/oem/SD_SDIO_specsv1.pdf

as you can see the transfer is using 4 bits. mmc is with 1 bit interface. maybe sd works with one bit too. You would first see how you make it work with sd, filesystem is a later development problem. there are a lot of pieces of code, but it won't be easy. it's not a 2 day job.

ben2
Associate II
Posted on September 26, 2005 at 04:52

the SD cards can be put into an SPI mode. I know this as a colleague has connected an SD card to the SPI bus. Cant help for the file system though as the SD card was memory addressed.

janek
Associate II
Posted on September 29, 2005 at 20:02

1) www.google.com

2) search for... (what you need)

3) RESULT:

http://www.ulrichradig.de/