Re: Confused about synchronous communications


"Jan Panteltje" <pNaonStpealmtje@xxxxxxxxx> wrote in message
news:fcusqe$qqd$1@xxxxxxxxxxxxxxxxxx
On a sunny day (Thu, 20 Sep 2007 22:28:37 GMT) it happened "Jon Slaughter"
<Jon_Slaughter@xxxxxxxxxxx> wrote in
<puCIi.8205$JD.5493@xxxxxxxxxxxxxxxxxxxxxxxxxx>:


But then this has a problem of the data changing towards the end of the
clock.

So, I guess my actual question is, when is it required for the data to be
valid?

Depends on the system.
Some systems data is clocked in on the positive edge of the clock,
and in some systems it is clocked in on the negative edge.

And, there could be systems were data is latched when the clock is high,
and systems where data is latched when the clock is low......

In i2c you need to pay especialy attention to start and stop sequences
too..

Yes, but I don't think that is anything to difficult? I just have to make
sure I set the lines correctly and wait atleast the minimum times.

Look at the datasheets is all I can say.

I did but was confused when exactly the data on the data line had to be
correct. They show the data edge right and the clock edge rise at the same
time. This can't work though and I didn't really notice the clock was 2x as
fast ;/ It make sense and everything but I really wanted to make sure
before I went any farther with my code(which I essentially have the clock at
the same rate as the data(but I was just testing my code with some leds so
it wasn't critical).


Thanks,
Jon


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