SparkFun Forums

[dak246]

Does anyone have a link to a simple project like this, or at least an interface component of a more complex project? I'm programming in ASM but any (almost) standard language would do as a reference. I can do it from the ground up using the protocol and datasheet but I don't really wanna reinvent the wheel if i don't have to and generic parts of a project go a lot faster IMO with a sort of "outline" to follow. Thanks in advance guys.

[rod_vdb]

I assume that microSD is just the SD communication spec in a different package? If so you will have to communicate with the memory using SPI. To communicate using paralell you have to pay lots of $$ to the SIG to get the specifications.

try microchip forums http://forum.microchip.com

[upand_at_them]

Google "pic mmc" and you'll find a few helpful links.

Mike

[Kuroi Kenjin]

Microchip has an appnote on this, but it's using USB as an interface, implementing a simple Mass Storage Device. This is really useful, but you have to dig through a lot of C code (and I mean about a good 10+ source files). The application note also has a self install to setup the workspace and such.

[dak246]

All I seem to be finding is mmc. This isn't the same format as SD is it? And is SD a general format that includes transflash or are they different?

[SOI_Sentinel]

SD should be close to MMC for the SPI interface (it's supposed to be backwards compatible). I don't know about transflash. One of the biggest problems you're running into is proprietary/copyrighted/patented information that you'd need to spend several thousand dollars to access. That's one reason why you don't see many xD or full speed SD card interfaces on hobby projects, they're liabilities.

[dak246]

I assumed getting info would be a problem but I also assumed I'd just use a serial interface to avoid that very problem. Basically I wanted a convientent source of flash memory, and being removeable gives it that much more flexibility.

[dak246]

I found one promising reference here http://www.k9spud.com/sdcard/ but it seems to only read/write a single block. Also I found somthing here www.edwaugh.co.uk (thats where it should have originated from anyway)for mmc, which should be relatively the same, but I'm not sure. The topic on the microchip forums is all over the place and the most recent posts seem to still be grappling with initialization. Anyway I'm gunna go through this code and the manual and see if I can come up with somthing that specifically works for the microSD while I keep trying to look and see if it already exists somewhere else in the public domain.

[Kuroi Kenjin]

Odd, one site doesn't seem to exist and the other seems to have nothing about SD/MMC.

I have a few sites that have code and I'm still looking for one with the SPI spec for SD/MMC. It also contains a bit of the 4 wire bus, but the 4 wire bus looks like more trouble than it's worth... such as one bit between open-collector input to some other type (push-pull?). I may just upload the pdf's to my website and link off them for download. I'll probably do this tonight.

(forgot to link the one website I found)
http://www.captain.at/electronics/

and found another
http://www.microchipc.com/sourcecode/#mmcint

[dak246]

and found another
http://www.microchipc.com/sourcecode/#mmcint

This is the code that my second link is referring to...it should be the link in the code header. However now it just seems to be the personal page of the person who wrote it. The first link should work, and should bring up code specifically about SD, but its basic and rough. I'll have to take a look at the first site you linked and see what I can find.

[Kuroi Kenjin]

Odd, that one site you mentioned started to work finally.

Found the technical specs... They'll be on my website under the projects catagory... probably labeled "SD/MMC info". (link to my site in my signature) (This will be up momentarily.)

anyways, here is another site I stumbled upon when I was searching for the PDFs... there are a few links on the bottom which may be helpful too.

http://www.freelabs.com/~whitis/sd_card/