Lpc2000

rtstofer wrote:

>I have a pointer to an unsigned 32 bit value in an array[512] of 
>unsigned chars (actually the partition table of a CF).  When I point 
>to the value using GCC, it seems that the code is assuming I am 
>pointing at the high word and that the low word precedes the high word 
>in memory.
>
>I think I am pointing at the low word and the high word should follow.
>
>The byte order within the two 16 bit words is correct.
>
>Any thoughts about what I am doing wrong.  I can see the sector dump 
>and I can see the results of extracting values and the results are 
>wrong.  Bytes work and 16 bit words work but 32 bit words do not.
>
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>

You might have a hardware problem where you are byte swapping?  Try 
running an IDENTIFY_DRIVE (0xec) command on the CF.  This will send you 
back a bunch of bytes structured as:

=============== begin ==================
struct DriveID {
  Word Signature;
  Word NumCylinders;
  Word Reserved1;
  Word NumHeads;
  Word NumUnBytePerTrack;
  Word NumUnBytePerSector;
  Word NumSectorsPerTrack;
  DWord NumberSectorsPerCard;
  Word Reserved2;
  char SerialNumber[20];
  Word BufferType;
  Word BufferSize;
  Word EccBytesPassed;
  char FirmwareRev [8];
  char ModelNumber [40];
  Word Max1SectorRW;
  Word DWnotSupported;
  Word Capabilities;
  Word Reserved3;
};
=============== end ===================

Try looking at the text string: ModelNumber.  That will tell you if byte 
swapping is the problem.

I ran into byte swapping issues between the IDE registers and the Data 
register while working with a big-endian controller (MC68EZ328).

IIRC, something tells me that the drive data is Big-Endian on the CF and 
IDE drives...


TomW


>Richard
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-- 
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net, http://cyberiansoftware.com
"Windows? No thanks, I have work to do..."
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