How to convert the DWT CYCCNT to ns ?

[gapryun]

Posted on July 15, 2014 at 17:26

Dear

I have read Ch16.2 Trace component DWT, the definition guide of Cortex M3 2nd. But I still confuse it. 

If I take the CYCCNT, the corresponding time is CYCCNT * 168 MHz * 1e9 ?

Am I correct?  

Thanks 

[Tesla DeLorean]

Posted on July 15, 2014 at 17:36

You understand the basic relationship between frequency and period, right?

At 168 MHz each tick is about 5.95ns

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[gapryun]

Posted on July 15, 2014 at 17:49

Sorry, clivel, My smartphone have strange problem so it did not submit my question.  For now, I have updated. And thank you for your nice reply.

[Tesla DeLorean]

Posted on July 15, 2014 at 17:58

This forum does not work well with smartphones or tablets

>> CYCCNT * 168 MHz * 1e9

You need to make an initial, and final measurement, and subtract them to understand how many ticks occurred in the measurement period.

Then  (DeltaTicks / 168000000.0) * 1e9 would give you nanoseconds