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SD/MMC card FAT module? (need to write data log to SD card) — Parallax Forums

SD/MMC card FAT module? (need to write data log to SD card)

charliezcharliez Posts: 6
edited 2006-06-29 08:44 in BASIC Stamp
Is there an SD/MMC card FAT module that I can use to write to an SD card?

How are you folks doing it? Does Parallax make one? Is there an article in Nuts & Volts I haven't read?

Thanks!

Comments

  • aridaiosaridaios Posts: 57
    edited 2006-06-22 06:45
    Please check

    MMC-RTC1 at

    http://www.bipom.com/periph_boards.shtm

    and

    from

    uMMC Serial Data Module
    http://www.roguerobotics.com/products/electronics/ummc

    Michael
  • BeanBean Posts: 8,129
    edited 2006-06-22 11:51
    I sell one at www.sddatalogger.com that is "Stamp Friendly".
    You can download the datasheet there too.
    Bean.

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    Cheap 4-digit LED display with driver IC·www.hc4led.com

    Low power SD Data Logger www.sddatalogger.com

    "I reject my reality, and substitute yours." NOT Mythbusters
    ·
  • dandreaedandreae Posts: 1,375
    edited 2006-06-22 19:02
    Along with the data sheet there are sample programs for the BASIC Stamps listed at www.sddatalogger.com.·

    Dave

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    Dave Andreae

    Tech Support
    dandreae@parallax.com
    Http://www.parallax.com

    ·
  • charliezcharliez Posts: 6
    edited 2006-06-22 21:29
    Well, by module I meant source code library smile.gif I've found Rogue Robotics and uALFAT boards, as well as compsys (but that is really raw code).

    If possible, I'd rather not add to the chip count (need more power, and routing complexity) and board space (need more physical space)
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-06-22 22:04
    charliez -

    If you're thinking that you may be able to access an SD/MMC card without some sort of external hardware, it's just not going to happen. In fact, there is no access to any mass storage device with most microcontrollers. They're just not "geared" that way.

    If you're looking for a standard library that will work with any of these devices, there is no standard, and thus no library, I'm afraid.

    I can tell you from personal experience, that the SD Datalloger that Bean is offering works flawlessly:
    www.sddatalogger.com

    It also offers "free" RAM storage if that is required for your application, and I don't believe the other products offer that advantage. It also is able to write both fixed and variable length records.

    Regards,

    Bruce Bates

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  • charliezcharliez Posts: 6
    edited 2006-06-22 23:42
    Hi Bruce,

    www.compsys.com has a board with source code for the Pic microcontroller. It might not be possible with Basic Stamp due to code size limitations but possible elsewhere.

    The sddatalogger looks interesting and small, but it is pricier than a uALFAT chip/board.

    Thanks!


    ·
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-06-23 05:26
    charliez-

    The uALFAT is only cheaper if you don't do your homework. The SD Datalogger comes with a 32 MB SD card, the uALFAT comes with NONE. The uALFAT requires a 3.3 V regulated power supply which is probably not available, which you must provide, but the SD Datalogger will work fine with ANY voltage from 3.6 volts to 7.2 volts. With the uALFAT you will also have to supply a 32 KHZ crystal, and no such crystal must be added to the SD Datalogger.

    After you price up the additional things you need to add to the uALFAT, I think you'll find the SD Datalogger is quite a bargin at the indicated price of $69.95 US.

    Regards,

    Bruce Bates

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  • charliezcharliez Posts: 6
    edited 2006-06-23 06:24
    Bruce,

    Certainly an interesting perspective, and seems I could use your insights here.

    I am really looking at this from a production perspective. If I have to add to the chip count, I'd like to do it with as least cost as possible (I will not be buying unneeded components such as an SD card my customers won't use). Power supply components are simple to add with SMD devices, as are crystals. Total cost is still less than SD datalogger. With firmware and thus no additional chips, I can do without more board space, or power consumption.

    With the rage of flash MP3 players there must be a solution to this problem that combines the mcu and SD access into one chip.

    Am I wrong here?

    Thanks!
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-06-23 06:49
    charliez -

    Just for future reference, and to avoid any additional confusion, what you're looking for is called an OEM (original equipment manufacturer) solution. Most folks who have asked for SD/MMC card access here on these forums want a single BOARD (not single chip) solution. They're not really interested in building up the chip so it can be used with their microcontroller.

    In your case, you may want to look at the uALFAT chip only:
    http://www.ghielectronics.com/uALFAT.htm

    Regards,

    Bruce Bates

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    Post Edited (Bruce Bates) : 6/23/2006 10:16:15 AM GMT
  • BeanBean Posts: 8,129
    edited 2006-06-23 15:30
    Charliez,
    Please contact me if you are interested in using my data logger in an OEM solution.

    terry@hittconsulting.com

    bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Cheap 4-digit LED display with driver IC·www.hc4led.com

    Low power SD Data Logger www.sddatalogger.com

    "I reject my reality, and substitute yours." NOT Mythbusters
    ·
  • Tracy AllenTracy Allen Posts: 6,664
    edited 2006-06-23 15:52
    A nice thing about Bean's SDdatalogger is that it has a single line SERIN/OUT interface to the Stamp. The Roguerobotics card takes 2 lines (separate serin and serout), and the uALFAT takes 4 or 5 lines (depending on which interface you use, including the handshaking lines).

    Another issue is pacing: After the Stamp issues a command with a SEROUT, it takes about a millisecond for it to set up the SERIN command to receive the response. That response might be data or it might be an error code or a handshake. The SDdatalogger has a configurable delay between characters. In constrast, both the Roguerobotics card and the uALFAT return many of their responses too fast for the Stamp to pick them up. I have been able to get those other cards to work with the Stamp, but it takes workarounds, as the error codes are lost and the system has to operate open loop. The uALFAT does have three interfaces, not only serial but also fast SPI and I2C (!), and lots of advanced capabilites, but it is more complicated and has more signal wires to the Stamp. The SDdatalogger is much more Stamp friendly.

    By the way, Bruce, I think the 32khz crystal for the uALFAT is required only for the RTC function, not for the memory, and I'm not sure the RTC commands are actually implemented.

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    Tracy Allen
    www.emesystems.com
  • BeanBean Posts: 8,129
    edited 2006-06-23 18:36
    Bruce,
    I have been told that JUST the 32K of RAM with the serial interface is worth the price of the data logger. And your right those 32MB cards are hard to find. And do add somewhat to the price. But I wanted to give customers a "Ready to go" solution.
    If you have a BOE board, you can just plug in the 3-wire cable into one of the servo connectors, and you're off like a prom dress.

    Bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Cheap 4-digit LED display with driver IC·www.hc4led.com

    Low power SD Data Logger www.sddatalogger.com

    "I reject my reality, and substitute yours." NOT Mythbusters
    ·
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-06-23 19:31
    Bean -

    You're right as rain regarding finding those 32 MB cards, but I honestly didn't look too hard, since, as you know, one can use the SD Datalogger's "Convert" (!CC) command which apparently re-calculates the geometry of larger cards. That's another real nice feature. I can use the 128 MB SD card I have either in the SD Datalogger, or in my digital camera. That also saves a few bucks!

    Maybe we should give it the kindly nickname of "The Penny-pincher" smile.gif That does NOT reflect the professional construction of the unit however, I should point out!

    Regards,

    Bruce Bates

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  • charliezcharliez Posts: 6
    edited 2006-06-23 20:17
    Many Thanks all, this gives me enough info to ponder which solution to go for!
  • sharpiesharpie Posts: 150
    edited 2006-06-29 08:44
    http://www.comfiletech.com/index.asp?PageAction=VIEWPROD&ProdID=79&HS=1

    Simple, easy and fairly cheap.
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