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Strange timing on pin writes | Cypress Semiconductor

Strange timing on pin writes

Summary: 2 Replies, Latest post by danaaknight on 06 Sep 2014 04:36 AM PDT
Verified Answers: 0
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euggersh's picture
1 post

 I'm seeing some strange behaviour writing to pins on a PSoC 5LP.  I'm writing a 6-bit value to six pins grouped as a bus.  I'm then writing a 1 followed by a 0 to a separate pin.  The changes on some of the bits within the bus don't always happen concurrently.  In fact, some of them occur *after* the strobe is cycled.

Here's the code I'm using:


Here's what the resulting timing looks like.  Anyone know what's going on?

user_1377889's picture
9260 posts

It is a bit difficult to judge from a picture what the cause of the strange behavior is. Can you post your complete project, so that we all can have a look at all of your settings? To do so, use
Creator->File->Create Workspace Bundle (minimal)
and attach the resulting file (do NOT use chrome, that still may not work).



user_14586677's picture
7646 posts

First the Saleae logic analyzer way too slow to get accurate timing.

Although display you show is relatively (within 135 nS) correct.


Consider a scope and look at the trigger vs a specific channel. In fact

you can trigger DSO on a pin changing before strobe as a condition.

Or on a condition of excessive delay of a pins response.


What is used as the trigger, the STB ?


Regards, Dana.

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