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I want to connect an MCP2562 to an ESP32 IC. I have desinged a PCB to accomdate these two ICs. The CAN bus runs at a 250 baud rate.

I have done some research on how long the stubs must be between the CAN bus and the node and came across this link. It details the max length of a stub as per the formula. However, I cannot find out how they calculated this:

"The CAN controller is set up to have PROP_SEG equal to 1100 ns" which is quite important. How do I calculate the PROP_SEG parameter for the MCP2562? Can someone assist?

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  • \$\begingroup\$ The stubs must be less than the max length. You want the stubs to be as short as possible or not have stubs at all. The link you gave shows how the PROP_SEG was calculated. Find the prop delay values in the mcp datasheet and calculate. \$\endgroup\$
    – Kartman
    Commented Oct 12, 2021 at 12:51
  • \$\begingroup\$ @Kartman I have gone through the datasheet 10 tmes now and still cannot see this value. I also checked the example in the link and still do ot understand how they calculated 1100ns for that link. Can you assits? \$\endgroup\$
    – JoeyB
    Commented Oct 12, 2021 at 12:53
  • \$\begingroup\$ Section 2.3 of the mcp datasheet has the values of interest. Page 3 of the link you provided has the calcs. The mcp chip has similar figures to the onsemi. \$\endgroup\$
    – Kartman
    Commented Oct 12, 2021 at 13:00
  • \$\begingroup\$ @Kartman Thanks for the info, but I still not getting the 1100ns \$\endgroup\$
    – JoeyB
    Commented Oct 12, 2021 at 13:13
  • \$\begingroup\$ I wrote a post explaining the relationship between baudrate, prescaler and time quanta just the other day: electronics.stackexchange.com/questions/589317/…. You set this in the CAN controller so all of this has very little to do with MCP2562 since that's a "dumb" CAN transceiver. \$\endgroup\$
    – Lundin
    Commented Oct 13, 2021 at 6:25

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