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SD Memory Card - Microcontroller Interface

Hello,

I don't have a particular project in mind, but it seems like having

512+MB of memory at my disposal for microcontroller projects would be quite amazing. From a few of the posts I've read, and the limited specs I could find, it seems like Secure Digital (SD) memory cards allow for an SPI interface (serial) and run anywhere from 0-25Mhz. (I've interfaced to CompactFlash cards and Cardbus, and SPI seems much easier, in concept)

But a few of the articles I found about SD cards briefly talked about their security features and the need to pay the "Secure Digital People" for specs on the device and perhaps even some proprietary information on how to talk to the chip such that it will actually store and retrieve data. Is this correct?!

If there is any known work around, I would love to hear it. I guess that brings me to my two questions, shown below:

  1. What is the pinout for the SD card?
  2. What are the protocol specs to address the SD card, put it in read/write mode, and then access data? (a PDF datasheet would be helpful here)

I'm sure if there was a simple way to tap into the SD card, only requiring the small number of standard SPI pins, microcontroller projects with high storage capabilities would spring up everywhere since the pin count is so small and the memory sizes keep getting larger by the day. :) Thanks for your help!

Best Regards, Adam Kumpf

Reply to
akumpf
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Yeah, you gotta pay. Skip SD. Go with MMC. Same benefits, and you can still use SPI. The only down side is that MMC is less plentiful these days.

Reply to
Brett Foster

| snipped-for-privacy@gmail.com wrote: | || Hello, || || I don't have a particular project in mind, but it seems like having || 512+MB of memory at my disposal for microcontroller projects would be || quite amazing. From a few of the posts I've read, and the limited || specs I could find, it seems like Secure Digital (SD) memory cards || allow for an SPI interface (serial) and run anywhere from 0-25Mhz. || (I've interfaced to CompactFlash cards and Cardbus, and SPI seems much || easier, in concept) || || But a few of the articles I found about SD cards briefly talked about || their security features and the need to pay the "Secure Digital People" || for specs on the device and perhaps even some proprietary information || on how to talk to the chip such that it will actually store and || retrieve data. Is this correct?! | | Yeah, you gotta pay. Skip SD. Go with MMC. Same benefits, and you can | still use SPI. The only down side is that MMC is less plentiful these days.

I've recently purchased the MMC-RTC-1 board from Bipom, for use as data acquisition on a weather station:

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I'm still waiting for my order to either arrive in the mail or show up on my credit card bill. All that they sent me was a blank email as an order confirmation. Not exactly the best system.

Also, I didn't purchase an MMC card from them in hopes that I can buy one cheaper elsewhere, but I probably should have looked into that first.

Goodluck.

--
MT

To reply directly, take every occurrence of the letter 'y' out of my
address.
Reply to
mark thomas

Go to Sandisk's website, and get the MultiMediaCard spec in the OEM section. Develop your software against the MMC spec. If your software follows the MMC spec, it will talk to an SD card without changes. You don't need to know anything about the security features, and you don't need the SD card spec. The only difference will be that you'll need an SD-compatible slot, since the SD card is thicker.

--
John W. Temples, III
Reply to
John Temples

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Sandisk SD card product manual
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MiniSD card
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Older SD card specs

Using SDCard and SDIO with the Intel® PXA250 MMC Controller Application Note

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Toshiba SD card specification
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You can order the spec (version 3.31) for US$500 from

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Version 4 has been released.

These links may also be of some use.

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Reply to
dmm

days.

And you may well find that your MMC logic works with the SD card, which are likely to be downward compatible. You won't have SD features, but you won't pay the standards tax, either.

But there may be some issues requiring you to format the card as an MMC device.

Rufus

Reply to
Rufus V. Smith

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