Hi Jim,

Sorry for the late reply.  I have my old code that I used to communicate
with an MMC from a Windows machine thru a parallel port. Please tell me if
you wish to have the source code. I can mail you off the list. It is a VC++
COM component, a VB application also uses an external library to access the
parallel port directly in a Windows machine.
It took me this long to get this from my pile of backup CDs.

Regards,
Somasundaram,

----- Original Message -----
From: "Jim Swensen" <jswensen@VOLCANOMAIL.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, December 31, 2001 7:48 PM
Subject: [PIC]: BS2 to Sandisk MMC memory card?


> I've been trying for sometime to interface a Sandisk 16MB
> MultiMediaCard with a Parallax Basic Stamp 2 without success.
> The 5v Stamp pin signals have been converted to MMC levels (~3.18v)
> and using various application documents that I've found,
> I think I've got the physical construction right (logic probe looks
> good) but it doesn't act exactly the way it should. Specifically:
> To power up the card and initialize it into SPI mode (which I need to
> use), the documentations says to
> 1)send at least 74 (80 is suggested) clock pulses
> 2)set CS pin to LOW
> 3)send the reset command (CMD0), which is 0x4000 0x0000 0x0095 (I'm
> using SHIFTOUT/MSBFIRST)
> 4)send 8 clock pulse as delay
> 5)SHIFTIN 8 bit response code
> [until response code is 0x01, keep sending CMD0]
> 6)8 pulse delay
> 7)send the init command (CMD1), which is 0x4100 0x0000 0x0000
> (SHIFTOUT/MSBFIRST)
> 8)8 pulse delay
> 9)SHIFTIN 8 bit response code
> [until response code is 0x00, keep sending CMD1]
>
> At this point, the MMC should be in SPI mode and awaiting a command
> to read/write a block of data.
> The problem is that I can't get to that point. First, I cannot get
> ANY response from the card unless I
> send 21 plus a multiple of 25 clock pulses (21, 46, 71, 96, etc...).
> When I do that, I can send CMD0
> and loop the SHIFTIN of 8bits. This is what is (always in this order)
> shifted in:
> 1) 0111 1110
> 2) 0000 0011
> 3) 1111 1111
> 4) 1111 1111
> 5) 1111 1111
> 6) 1111 1111
> 7) 1111 1111
> 8) 1111 1111
> 9) 1111 1110
> 10)0000 1011
> ...bytes 3 through 10 then loop indefinitely.
>
> If, instead of looping the SHIFTIN, I continue sending CMD0 in order
> to get the 0x01 response code, I never get it.
> If I just continue on to issuing CMD1, the same thing happens which
> is shifting in that loop of blocks 3 through 10
> as if it's ignoring my CMD0 and CMD1 commands.
>
> I think I've exhaused every PDF and HTML document I could find on the
> subject and I'm hoping someone might
> have had the same problem and figured it out.
> ANY HELP IS APPRECIATED!!!
>
> thanks
> Jim Swensen
> [jswensen*volcanomail,com]
>
>
>
>
>
>
>
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