If a buffer component needed for fanout issues?

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Anonymous
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I'm running into odd problems with my design when I add extra gates to be driven from GPIO Pins. It looks sort of like a fanout issue. For instance, I have a R/W pin (low for write). It's a CMOS level Digital Input in my design. The solution works fine if this signal is connected to an AND gate input or a NOT input, but not if connected to both. I added a second NOT in series, so that the output from the first NOT could drive the AND gate (the pair acting like a buffer), and everything works again. It looks, in the case, like the extra load of both a NOT and an AND is too much for this R/W signal.

I would have thought, though, that the Pins themselves would act as buffers. There is actually an Input Buffer setting on the Input tab, and it is enabled.

There also is no buffer component in the palate, which again makes me think they should be needed.... but then why am I seeing this kind of behavior. I saw something similar when I connected another Digital Input pin to both a Status Register and a NOR gate. One or the other works, but not both.

This is on a CY8C5888.

Thanks,

Paul

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1 Solution
Anonymous
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Bob pointed out in another thread that some files were missing from my project. I had retargeted from PSoC 4, and I guess I must have done something wrong along the way. Creating a new project and copying everything over from it makes for more correct behavior.

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4 Replies
Bob_Marlowe
Level 10
Level 10
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Can you please post your complete project or a shortened version that shows the error 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.

Bob

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Anonymous
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Here you go.

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Anonymous
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Sorry... here's the attachment. One issue is the Pin RW connection, the other is Pin_Address_High_3, which I would have liked to connect to that NOR gate at the bottom as well as to the Status Register, but, for now I just have the Logic High connected to the NOR gate instead. The Pin_RAMCS output is not currently used, though it will be eventually. 

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Anonymous
Not applicable

Bob pointed out in another thread that some files were missing from my project. I had retargeted from PSoC 4, and I guess I must have done something wrong along the way. Creating a new project and copying everything over from it makes for more correct behavior.

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