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Removable memory cards and the SX — Parallax Forums

Removable memory cards and the SX

Paul BakerPaul Baker Posts: 6,351
edited 2008-06-16 00:00 in General Discussion
I remember in one of the threads about people contemplating interfacing the SX with removable memory cards, since I can't seem to find the pertinent thread I'm starting a new one. Atmel sells a memory card in MMC/SD format which is compatable with the SPI serial protocol, Digikey sells the 2 MByte version for under $10 (the 4MB is $17 and 8MB is $28)·and offers·several vendors recepticles (my fav is the Hirose Electronic DM1 series·push in/push out insertion/ejection mechanism for under·$4). So if you have an application which could really use a removable memory card, this is a definate option for you. One note though, not all MMC/SD cards are compatible with SPI, so if you don't use the atmel card be sure that it is SPI compatible before buying it.

Paul··

Comments

  • David BDavid B Posts: 592
    edited 2004-12-02 19:09
    I played around with an MMC card in SPI mode a while ago. I made a socket out of an old printed circuit card edge connector, made TTL - 3.3 volt translation circuits out of discrete transistors, and hooked it to my PC parallel port.

    I wrote a demo program in Borland Delphi which successfully initialized, read and wrote to the MMC card. It eventually worked, but took a lot of debugging with all the bit processing involved - interleaving input and output bits, alternating commands, data and responses, testing for errors and timeouts, etc. Once it finally worked, the programming really wasn't too complicated.

    A few years ago I made a GPS NMEA position message logger using an 8 MB PDA to save the data; since then I've wanted to make something similar using a Scenix and a hundreds of megabyte flash RAM card. Just never got around to it.

    David
  • Peter VerkaikPeter Verkaik Posts: 3,956
    edited 2004-12-03 13:45
    Here is an application that uses MMC for audio recording/playing.
    http://www.sxlist.com/techref/ubicom/contest/mmc/sx52mmc.src

    regards peter
    ·
  • Tracy AllenTracy Allen Posts: 6,666
    edited 2004-12-04 18:54
    Hi Paul,

    I use the Atmel AT45 series memory for data logging with the Stamp. I 've not come up with an interface to the PC, and have to read out the data via the Stamp. I think standard MMC card drivers would not work, even if theyready made PC interface and drivers I would like to know about them. Even without the PC interface, the cards and the chips do make great big memories for the Stamp or SX.

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    Tracy Allen
    www.emesystems.com
  • Timothy D. SwieterTimothy D. Swieter Posts: 1,613
    edited 2008-06-15 06:23
    I had some quesitons about using SD cards with the SX. I searched through the forums and found this old thread. I thought it was hilarious how Paul points out that an 8MB card was US$28! Today we talk about GB cards being cheap!

    Anyway, wany one go any further with interfacing an SD Card with an SX? I am considering it for an upcoming project. SPI mode, of course. I could use the SD card as a general storage or, if code existed, it would be great to log data in a FAT16 format and then the card could be read by a PC. I have played very minimally with the SD cards with the Propeller. I even have the HYDRA SD Card, but I have not used it much yet. Perhaps with the information in the manual and on the web some code could be cooked up. Thoughts on viability for the SX (I am not too familiar with it yet)?

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    Timothy D. Swieter

    www.brilldea.com·- uOLED-IOC, RGB LEDs, TLC5940 driver PCB
    www.tdswieter.com
    One little spark of imagination is all it takes for an idea to explode
  • BeanBean Posts: 8,129
    edited 2008-06-15 12:37
    Timothy,
    · The biggest problem with using the SX is that you must read/write sectors of 512 bytes, and the SX doesn't have that much RAM. So you must use an external RAM chip.

    · I have made the SD Data Logger using the SX48, but it is limited to 32MB cards (but only because the firmware only supports 512 byte clusters).

    · If you would like to "play" with here it is...

    Bean.

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    Did you know that 111,111,111 multiplied by 111,111,111 equals 12345678987654321 ?

    www.iElectronicDesigns.com
    pdf
    pdf
    SD Data Logger Schematic Rev A.pdf
    27K
    SXB
    SXB
    DataLogger 1_4.SXB
    52K
    pdf
    pdf
    SD Data Logger Rev A-B.pdf
    261K
  • Timothy D. SwieterTimothy D. Swieter Posts: 1,613
    edited 2008-06-16 00:00
    Thanks Bean for the insights! I hadn't considered the block read/write limitations. I think for the application I am considering 32MB should be fine, but I need to explore it more.

    I will review the wealth of information you attached.

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    Timothy D. Swieter

    www.brilldea.com·- uOLED-IOC, RGB LEDs, TLC5940 driver PCB
    www.tdswieter.com
    One little spark of imagination is all it takes for an idea to explode
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