SPI vs SGPIO

Sheffield, Robert L robert.l.sheffield at intel.com
Mon Aug 9 15:42:26 PDT 2004


* From the T10 Reflector (t10 at t10.org), posted by:
* "Sheffield, Robert L" <robert.l.sheffield at intel.com>
*
Definitely TLA overload here!

SPI (Serial Peripheral Interface), on the surface, bears some similarity
to SGPIO (4 signal lines, serial I/O,...),
But one doesn't need to dig very deep to identify some significant
differences:

SPI's 4 signal lines are:
	Serial Data Out (SDO)
	Serial Data In (SDI)
	Serial Clock (SCK)
	Slave Select (SS)

SGPIO's 4 signal lines are:
	SClock
	SLoad
	SDataOut
	SDataIn

The first notable difference is that SPI has no "SLoad" signal. This is
instrumental in SGPIO to identify data boundaries. SDI pretty much deals
with transfers a byte at a time, whereas SGPIO deals with a
comparatively longer stream of bits in groups of 3 where each group of 3
corresponds to a drive slot. The Slave Select signal in SPI is defined
only for the Slave, and assumes a control mechanism outside the SPI
definitions, and so isn't suitable for use as SLoad, even if it were
possible to manipulate the timing to match SGPIO requirements.

In my view, the SPI signal definitions are different enough from SGPIO
that, at best, it would be a difficult task to manage them in a way that
works for an SGPIO target, and I think it's unlikely you'll find any
existing SPI implementations that provide a register interface such that
software could make the SPI work like SGPIO.

Bob Sheffield


-----Original Message-----
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of
Paul.A.Suhler at certance.com
Sent: Monday, August 09, 2004 2:24 PM
To: t10 at t10.org
Subject: Re: SPI vs SGPIO

* From the T10 Reflector (t10 at t10.org), posted by:
* Paul.A.Suhler at certance.com
*

Hi, Hugh.

Indeed it is, but's it's also "serial peripheral interface."  Here's one
of
many links that a search turned up:

  owner-t10 at t10.org, t10 at t10.org

Cheers,

Paul Suhler
Certance, LLC



 

                      "Hugh Curley"

                      <hcurley at indra.co        To:       "Kevin Khuu"
<kevin98146 at hotmail.com>                                         
                      m>                       cc:       t10 at t10.org

                      Sent by:                 Subject:  Re: SPI vs
SGPIO                                                              
                      owner-t10 at t10.org

 

 

                      08/09/2004 01:00

                      PM

 

 





* From the T10 Reflector (t10 at t10.org), posted by:
* "Hugh Curley" <hcurley at indra.com>
*
Kevin,

I think that SPI is "SCSI Parallel Interface."

Hugh Curley



----- Original Message -----
From: "Kevin Khuu" <kevin98146 at hotmail.com>
To: <t10 at t10.org>
Sent: Monday, August 09, 2004 1:11 PM
Subject: SPI vs SGPIO


> * From the T10 Reflector (t10 at t10.org), posted by:
> * "Kevin Khuu" <kevin98146 at hotmail.com>
> *
> Is Serial Peripheral Interface (SPI) compatible with Serial GPIO
(SGPIO)?
> Can I take a microcontroller (ie. Microchip 16F872) that has an SPI
> interface, hook up to the SGPIO bus and use it to control LEDs?
>
> Thanks,
> Kevin




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