• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 2 answers
  • Subscribers 33 subscribers
  • Views 736 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCAN1044A-Q1: Wake Up Pattern and Follow-Up

Kevin Schmidgall
Expert 3860 points
Part Number: TCAN1044A-Q1
Other Parts Discussed in Thread: TCAN1146-Q1, TCAN1145-Q1, TCAN1144-Q1

Hi,

I have some general question related to wake up pattern and maybe more broad automotive use-cases.

It is my understanding that there is no explicit addressing scheme in CAN. To me, this means that if a WUP is sent on the bus then all remote devices will wake up. Is that correct? If yes, then my question would be what is the typical implementation for wake-up and then follow-up for low power applications: for instance you want to send a specific message to 1 remote ECU but let the others go back to sleep would the overall scheme be 

  1. receive WUP
  2. wait for next message to see if it is for me
  3. if yes, do something. If no, go back to standby

Regards,

Kevin

  • 0
    TI__Mastermind 26806 points

    Hey Kevin,

    Good question, thanks for posting. The behavior you're describing is called "selective wake" or "partial networking" (the former is technically the feature of the transceiver, while the latter is the resulting capability of the network, but these terms are used interchangeably). Our partial networking transceivers are the TCAN1145-Q1 and TCAN1146-Q1.

    Partial networking lets you do exactly as you describe above, where the device can selectively wake up based on the information in the wake-up frame.

    There is some good material that explains how this feature works. Check out the application note How Selective Wake Enables Partial Networking (SLLA521) [link], or also check out the TI Training [link] and E2E blog post [link] that describes it.

    The TCAN1144-Q1 is pin-to-pin with the TCAN1145-Q1 and TCAN1146-Q1 except that it doesn't have selective wake. It allows designers to create boards that allow for a software later software upgrade by replacing with the tCAN1145-Q1 or TCAN1146-Q1 without needing a board refresh (or to offer a product option with/without partial networking).

    Best,

    Danny

  • 0 in reply to Danny Bacic
    TI__Expert 3860 points

    Hi Danny,

    Thanks for the quick response!

    Let's say the dont want to use selective wake. Would it operate to my understanding in the original question - a WUP wakes up everything on the bus and then it is up to the remote ECU to decide if it responds to the next message?

  • 0 in reply to Kevin Schmidgall
    TI__Mastermind 26806 points

    Kevin,

    Yes, exactly correct. Operation for devices with standard wake is that they will all awaken when a WUP occurs (which, in most cases, is just the beginning of communication, but could technically be a dedicated WUP). It would then be up to the MCUs to determine whether they should stay awake.

    The TCAN1144-Q1 would behave like this. It allows you to get the PN footprint implemented (and also the watchdog + bus fault detection of the TCAN1146-Q1) without actually having selective wake. It's a good way to transition if you as a designer are still using CAN with standard wake, but want to be ready for implementing it quickly if needed in the future. We do see increasing adoption of this across the market.

    Best,

    Danny