PWM period/Duty calculation

[AjRj14]

Hi, 

I am following below application note for PWM period calculation

https://www.nxp.com/docs/en/application-note/AN5303.pdf

For PWM period calculation, single edge capture mode is used, but Timer overflow is not considered .

Could you please tell me why timer overflow is not considered?

The PWM period is calculated by : In the interrupt routine, save the value of
the CnV register into a variable and make a difference between the current value and the saved value
from the previous interrupt routine. 

My understanding is when the counter reaches 65535, it then again starts counting from 0. In such a case the current counter value can be lesser than the counter value saved in previous IRQ. So the difference will become negative and incorrect. How is this incorrect counter difference handled?

[Robin_Shen · Accepted solution]

You're right. We can add a software counter to the overflow interrupt to overcome this problem.
Unfortunately, the current SDK does not support this function temporarily, so you will be prompted about the limitations of the current settings

Best Regards,
Robin
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[AjRj14]

Thanks for the reply