RM44L920: eCAP capture mode incorrect event capture.

Hi Karthik,

KARTHIK R said:

I am using eCAP module in continous capture mode,i found that at some times the two event capture values are same (C1:11539,c2:11539,c3:93510,c4:331453) c1,c2c,3c,c4 are the capture event values.

Why it can't be same? It might coincidence, right?

what signals are you capturing?

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Thanks & regards,
Jagadish.

No Jagadish it cant be same i am using eCAP module to measure wheel speed.the expected time difference is 200 micro seconds (apprx 12000 tick value).so it should not be the same for two capture events.

Is there any other module which i could use to measure wheel speed by pulses.Can you suggest me if there anything where i need to use every pulses without filtering the incorrect data.

Hi Karthik,

KARTHIK R said:

I am using eCAP module in continous capture mode,i found that at some times the two event capture values are same

The only thing i am suspecting is that,

As you can see that minimum pulse width for capture should be 2 times of the VCLK3 period right. In your case if the pulse width between the capture event-1 and capture event-2 is less than this required pulse width then before the counter increment to the next value you will get capture the two periods for event-1 and event-2 and in this case both captures would be the same values.

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Thanks & regards,
Jagadish.

Hi Jagadish,

I understood what you say,but if the two eCAP capture values are same then how am i supposed use those values if i need four pulses to calculate speed .Is there any alternate way to get the 4 eCAP values correctly without same value?