SPI Command IU CDB clarification

Sriram Srinivasan srirams at lsil.com
Tue Sep 5 15:24:42 PDT 2000


* From the T10 Reflector (t10 at t10.org), posted by:
* Sriram Srinivasan <srirams at lsil.com>
*
Brian:

   From the format of the table the describes the command IU in SPI and from the 
table that describes the CDB in SAM (table 8 in rev 12), for your example, the 
opcode of 0x2A would occur on byte 19 of the command IU.
   
   Sriram 
>
>* From the T10 Reflector (t10 at t10.org), posted by:
>* "Day, Brian" <bday at lsil.com>
>*
>
>I've had another engineer interpret the CDB field differently than I had in
>the SPI command IU CDB field.  The MSB/LSB notation was a little confusing.
>
>The CDB field is defined at bytes 4 through 19 in the Command IU
>(referencing Table 35 in SPI-3).  I've always thought the Operation Code for
>that CDB would be located byte 4, which would be the first byte of the CDB
>to get transferred across the bus.  However, my colleague interpreted it to
>be byte 19 because of the LSB notation.
>
>As a specific example, if an initiator was sending a 10-byte WRITE command,
>does the 0x2A come out on byte 4, or byte 19.
>
>Can someone please clarify....
>
>Brian Day 
>*
>* For T10 Reflector information, send a message with
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>



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 Sriram Srinivasan                       Sriram.Srinivasan at lsil.com
 ASIC Design Engineer, LSI Logic,
 2001 Danfield Ct., 				Phone: 970-206-5847
 Fort Collins, CO 80525				FAX  : 970-206-5244
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*
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