iMX RT-1064 CAN3 - minimal module clock

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iMX RT-1064 CAN3 - minimal module clock

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steffenrose
Contributor III

Currently I use a MIMXRT1064-EVK and want to use the following setting:

  • FLEXCAN3 clock 40MHz
  • all message boxes with CAN FD and payload 64
  • => so I think 14 Message Boxes
  • Bitrate 500k/2000k
  • bitrate settings according CiA1301

Bittiming - all real values, not register values - for 40MHz:

Arb 500k:

  • pre = 1
  • prop = 47
  • seg1 = 16
  • seg2 = 16
  • sjw = 16

Data 2000k:

  • pre = 1
  • prop = 6
  • seg1 = 8
  • seg2 = 5
  • sjw = 5
  • TDC offset = 14

From the configuration I use currently:

MB 0 - for TX errata

MB 1 / MB 2 - RX

MB 13 - TX

 

For my first tests it works. But I'm unsure about the requirements of Table 45-18.

@kerryzhou

Can you please check, if my clock of 40MHz is good or if I have to go to 80MHz?

 

Additional question:

Is my register value FLEXCAN_MCR_MAXMB(13) right for the maximum on this controller and my requirements?

 

Thank you

Steffen

 

 

 

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kerryzhou
NXP TechSupport
NXP TechSupport

Hi @steffenrose ,

   Thanks a lot for your trust.

   I am so sorry for the later reply, as a lot of cases overwhelming me, that I just find your case today.

  1. About the CAN module clock for 40M or 80Mhz

  I don't think this is must, if 40Mhz already works, you can use it, don't need to change 80Mhz.

In fact, just a divider.

 

  2. Is my register value FLEXCAN_MCR_MAXMB(13) right for the maximum on this controller and my requirements?

To the MB, The mailbox system consists of a set of 64 Message Buffers (MB).

If you need the 14MB, I think you can fill the 14 as the MAXMB number.

 

Wish it helps you!

If you still have questions about it, please kindly let me know.

Best Regards,

kerry

 

 

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steffenrose
Contributor III

@kerryzhou 

Thank you for your answer to question 1.

For question 2 - I don't understand.

 

We developp a communication stack and our customer set the requirements.
So I want to configure the possible maximum.

I understand table 45-25, that I have a max of 7 MB with 64Byte payload per RAM block.
So with 2 RAM blocks I can have a max of 14MBs.

Can I configure more, if needed?

Thank you.

Steffen

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kerryzhou
NXP TechSupport
NXP TechSupport

Hi @steffenrose ,

   Your understanding is correct.

 To the 64Byte payload, the max is 14 MBs, this is the detail situation: You can't see larger.

kerryzhou_0-1687252521519.png

 

Wish it helps you!

Best Regards,

kerry

 

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