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Question about MC9S12P64 COP watchdoge timeout rate.

Question asked by Byungwoo Park on Nov 21, 2014
Latest reply on Nov 25, 2014 by iggi

Hello This is Park, Byung-Woo from SL company in Korea.

 

I have a question about COP watchdog timeout rate

 

I use 16MHz XTAL, and I set CMPUCOP.CR register = 0x03.

According to table7-12.COP watchdog rats.  I can caculate COP watchdog timeout time is 163.84 ms (1/16MHz * 2^18)

 

I test watchdog timeout time using reset pin on MCU with Oscilloscope ,

The watchdog timeout time is 149.4 ms The difference is more than 10ms.

 

Can I know the reason? Thanks in advance.

 

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