At 09:55 PM 4/27/2005 -0500, you wrote:
>I went looking for the "original" SPI specification from Motorola a couple 
>of years ago. I ended up talking to an engineer at Motorola who was 
>supposedly the "expert" on such documents and she said that there was no 
>such document (or spec, for that matter). She said that SPI was originally 
>not intended for public consumption; it was for some type of internal 
>project and it just grow from that.
>
>In my search I did, however, find a number of articles and designs using 
>SPI that put a pull-up on the MOSI (master out/slave in or SDO, as it 
>appears on the PIC).
>
>Douglas Wood


In 2002, I posted a link to this document:
http://www.bio-bot.com/privateweb/datasheets/Processors/DSP/AN991.pdf
to comp.arch.embedded. It may be of some help, however I don't think
it's in any way essential.

Pullups? Well, I've designed them into SPI circuits, to handle transient
conditions.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com




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