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Altera_Forum
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12 years ago

Across clock domains problem

There are two main clocks in my project, one is 250MHz, antoher is 100Mhz. A counter counting according 250MHz clock. I want to register the counter's value at some conditions, and send this value in...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
12 years ago

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you would want at least a double register to get it "safely" across the domain. But how often are you going to read it? if its rather infrequently, and its set infrequently, then this method should be safe enough.

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Hi Tricky,

I read it after it is register correctly in 250MHz clock domain, so i generate SQOK signal to ensure that. It means the counter is read in 100MHz clock domain very later than it is registered in 250MHz clock domain, i can control the the SQOK postion(reading time point) as the BDF shows. I think it really like data exchange across clock domains using handshake control signals, am i right?

Thanks

Jerry