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Altera_Forum
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12 years ago

Is it save to use the PIO in QSYS

Hello, I have several PIOs in my QSYS design to communicate with some of my own designed IPs. My IPs mostly use other clock signals than the PCIe-Clock and are therefore not synchronized to t...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
12 years ago

No, that doesn't clear my doubt.

As you said: The PIO returns Pulsecounter data at the time of read request generated by Avalon Master. What if the Pulsecounter changes its value exactly the same time?

For example it changes from "01" to "10". If there is a little skew between the two bits, nearly every combination ("00", "11") is also possible to be seen by the PIO for a very short time. If the PIO samples the Data in this little piece of time, the Data should be corrupt. But I have never seen them corrupt. This is nice, but WHY?

I don't see how I should insert a Clock Crossing Bridge here. The PIO has no additional clock port and some of my other IPs are working asynchronously. So I can't predict when the Data are changing and when they are valid.