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PICList Thread
'Reed-Solomon code for PIC anyone?'
1998\04\19@135802 by rank A. Vorstenbosch

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Hullo!

I just found this completely marvellous Flash memory device, which would be
extremely suitable for PIC applications.  I'm currently reading the
KM29V64000T/R datasheet from Samsung, although other manufacturers exist as
well.  There's also a 29V32000.

Memory capacity of this little animal is 8650752 bytes (66Mb!) and it uses 16
signal lines only (including 8 address/data).  One of these pins is for write
protect, and could be connected to your system /Reset.   Power consumption is
10mA typical.

Memory is accessed in pages of 528 bytes, and -- clever people on this list
have already seen this coming -- 16 bytes of each page is intended for
error-correction codes.  These devices are for use in cameras and voice
recorders and things, and may have a few bad cells.  The datasheet suggests
mapping out bad blocks in software or using error correction on the data.

As most people know, Reed-Solomon codes are designed for just this kind of
thing, and it should be possible to implement a 512+16 byte RS error correction
code (and decoder) on a PIC.  If I remember correctly, the PC/XT hard disk
controller cards had one in their firmware.  Anyone have usable code on a PIC?
References, anything is welcome; I searched the web but nothing there seemed to
give the complete answer.

Frank
------------------------------------------------------------------------
Frank A. Vorstenbosch    <UCE_ACCEPT="NONE">    Mobile:  +44-976-430 569
Wimbledon, London SW19                          Home:   +44-181-544 1865
spam_OUTfrankTakeThisOuTspamfalstaff.demon.co.uk                      Office: +44-181-636 3391

1998\04\19@153932 by PIC development

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I have used a relative of this device (by the sound of it) called a
DiskOnChip (I wish people wouldn't mIx cases, it's a pain to type). This
uses a flash memory in a 32 pin "eeprom" format chip to emulate a disk
drive under DOS. You can get them in capacites up to 72 MB
but... they're expensive. I think the 72MB version is about 900 pounds.
It has a device driver that implements their own proprietary filesystem
called TrueFFS which sounds like it does all the Reed-Solomon stuff
on the PC.
Oh yes, it also does other smarts, like background deletions (slow)
and levelling the write operations across all the pages to prolong the
device life. I think Toshiba invented the technology and Samsung
second-source the devices.

check http://www.amplicon.co.uk (I am not connected to then - except
electronically :-)

A Pete

..............................................................................
. Never trust a man who, when left alone in ....... Pete Lynch               .
. a room with a tea cosy, doesn't try it on ....... Marlow, England          .
..........Billy Connolly. ......................... .....picKILLspamspam@spam@beowulf.demon.co.uk ..


On Sun, 19 Apr 1998, Frank A. Vorstenbosch wrote:

{Quote hidden}

1998\04\20@072937 by Steve Lawther

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    Frank,
   
    The parts you're on about are NAND flash (as made by Toshiba and
    second sourced by Samsung. - Nat Semi pulled out about 2 years ago.)
    For more info. see my web page:-
   
    http://ourworld.compuserve.com/homepages/steve_lawther/ssfdclog.htm
   
    (ignore the 'new' against it - it's a year since it was new, and I
    keep on missing it, when updating pages)
   
    I started a data logger based on the card version of the chip (card
    called SSFDC or SmartMedia) SmartMedia had (and still has) great
    potential, but despite years of Samsung / Toshiba marketing, can only
    be found in some digital cameras now and seems to be dying a death
    elsewhere. The project started because I got some samples from Toshiba
    and samsung rep.s
   
    The project was on hold because I needed to get hold of details of the
    Small Block Flash Format, as applied to SmartMedia cards, which is the
    format that PCs will recognise without requiring extra programs. Now I
    can't be bother to finish it, as I can't see a future for SSFDC - I'm
    drifting towards 'compact flash' as every man and his dog (SanDisk,
    Panasonic, Hitachi, Seiko-Epson, etc etc) is making them, and you can
    get 45MByte in them now (30M for GBP 150), although interfacing to a
    PIC is harder (IDE or ATA). Alteratively, there are the SPI- based
    Flash cards from ISSI, Sandisk, Atmel etc that are smaller in size
    (both physical and memory), but easier to interface.
   
    If SSFDC take off I might get back to it, but I doubt it. I'm
    currently deciding whether to dump that page on my web-site, or
    whether to put the unfinished code on there (circuit diagram and PIC
    code for reading / writing), and mark it as on permanent hold.
   
               Steve Lawther


______________________________ Reply Separator _________________________________
Subject:      Reed-Solomon code for PIC anyone?
Author:  MIME:frankspamKILLspamFALSTAFF.DEMON.CO.UK at INTERNET-HUSKY
Date:    20/04/98 11:34


Hullo!
   
I just found this completely marvellous Flash memory device, which would be
extremely suitable for PIC applications.  I'm currently reading the
KM29V64000T/R datasheet from Samsung, although other manufacturers exist as
well.  There's also a 29V32000.
   
Memory capacity of this little animal is 8650752 bytes (66Mb!) and it uses 16
signal lines only (including 8 address/data).  One of these pins is for write
protect, and could be connected to your system /Reset.   Power consumption is
10mA typical.
   
Memory is accessed in pages of 528 bytes, and -- clever people on this list
have already seen this coming -- 16 bytes of each page is intended for
error-correction codes.  These devices are for use in cameras and voice
recorders and things, and may have a few bad cells.  The datasheet suggests
mapping out bad blocks in software or using error correction on the data.
   
As most people know, Reed-Solomon codes are designed for just this kind of
thing, and it should be possible to implement a 512+16 byte RS error correction
code (and decoder) on a PIC.  If I remember correctly, the PC/XT hard disk
controller cards had one in their firmware.  Anyone have usable code on a PIC?
References, anything is welcome; I searched the web but nothing there seemed to
give the complete answer.
   
Frank
------------------------------------------------------------------------
Frank A. Vorstenbosch    <UCE_ACCEPT="NONE">    Mobile:  +44-976-430 569
Wimbledon, London SW19                          Home:   +44-181-544 1865
.....frankKILLspamspam.....falstaff.demon.co.uk                      Office: +44-181-636 3391
   

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