SD/MMC interface

Questions on control of serial busses
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YahooArchive
Posts: 1462
Joined: Fri Oct 19, 2012 5:11 am

SD/MMC interface

Post by YahooArchive »

Hi All.

I am trying to complete an interface to SD/MMC using the C code.
But I am having a terrible time with the SPI. I started with some
PIC/AVR code to drive the configuration. This has worked in the past
with faster PICs, but I can never get the ARM to initialize properly.

I have posted my code here:
http://gpscruise.wikispaces.com/space/s ... c_demo.zip

Its very small, and modular.

I am using the Coridium arm7 board with a Sparkfun microSd/mmc card.
I have checked the voltages, 3v on all. The SF card is like a raw
interface to a micro card.

Perhaps my timing is off, or maybe microSd's are just different.

Anyone who is interested in this, if you could look over the code,
maybe something just pops out. I fear I have looked at all this so
long that I am just missing the easy stuff.

I have in reserve code that provides FAT access, so I want to layer
that in afterwards. This should give us a nice MMC module to use.

Thanks all.
Joe



YahooArchive
Posts: 1462
Joined: Fri Oct 19, 2012 5:11 am

Re: SD/MMC interface

Post by YahooArchive »

Sad to reply to myself, but here it is.

Soon after posting this, I poked around and found a different example
of doing MMC. Using that and simplifying what I was doing I think I
got it working. Its better anyway. It seems to respond to to MMC
commands properly.

I haven't validated the data yet, but there it is.
The zip is updated in the previous reference.

I want to layer some FAT code I found on top and see if we can
read/write files and see them on a pc.

Thanks,
Joe

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