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MK20 approprite clock source for CAN

Question asked by Sudeep Chandrasekaran on Apr 29, 2019
Latest reply on Apr 29, 2019 by Mark Butcher

I am using an MK20DV256 for one of my projects. In the hardware(PCB) there are two clock available:

 

1. A 32 KHz RTC crystal connected to (XTAL32 and EXTAL32)

2. A 12 MHz crystal connected to (XTAL0 and EXTAL0).

 

We have derived the MCGOUT clock(~70 Mhz) from the FLL operating in FEE mode.

 

From what I understand I can clock the Flex CAN module from the below options:

 

1. The 12 Mhz crystal directly(OSCERCLK)

2. ~35.99 Mhz Bus clock.

 

Below are a few questions that I am trying to get answers to:

 

1. The clock to choose for the Flex CAN module seems to be dependent on the most accurate clock. How do we calculate the accuracy of the FLL stabilized MCGOUT clock?

2. Are there any other parameters that need to be considered before we choose the MCG clock.

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