Clarification of SPI

Shahe Krakirian x2130 shahe at
Fri Apr 8 11:35:17 PDT 1994

> There is a statement in rev 12b of SPI on page 22 that has aroused the
> interest of a few designers.  I was wondering if any of you could 
> enlighten me as to it's meaning.
> "The REQ/REQQ and the ACK/ACKQ receivers, after recognizing a negation
> transition, shall not respond to a signal reversal for at least 10 ns."
> What does this mean?

I interpret the statement as follows:

The input receiver has some type of 'filter' which is activated on the rising
(negating) edge of the strobe and remains activated for at least 10ns. During
that time, the strobe is internally forced to the negated state and all strobe
transitions on the bus (due to noise, reflections, etc...) are disregarded.

Any comments?


Shahe Krakirian
shahe at

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