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Can Transceiver : J1939 / Turbo Can

mosin
Expert 1160 points
Other Parts Discussed in Thread: SN65HVD251, SN65HVD255, HVDA551-Q1, HVDA553-Q1

Hi,

I'm currently working with the SN65HVD251 as a CAN transceiver to output J1939 frames. I'm revising the design and I came across the new SN65HVD255 supporting the Turbo CAN feature. First of all, I was wondering if there was an automotive version in the process? Second of all, there's no explicit mention of J1939 in it compared to the HVD251. Since J1939 is mostly software packaging, I was wondering if the HVD255 would work for J1939 protocol. 

Also, are there other TI's Turbo Can transceivers?

Thanks

  • 0
    TI__Mastermind 21911 points

    Hi Mosin,

    The J2962 standard is a higher layer protocol for CAN. It deals with message format and network management. Therefore, the SN65HVD255 transceiver can work with this protocol.

    The newer HVDA551 and HVDA553 devices are automotive qualified devices that use the same technology as the turbo CAN devices in the industrial market. It enable faster and more symmetric bit times.

    There are more CAN transceiver in development that will be using the turbo CAN technology.

    Please let me know if you have any other questions.

    John

  • 0 in reply to John Griffith
    Expert 1160 points

    Hi John,

    Thanks for the answer. When saying J2962, did you mean, J1939? 

    As for the HVDA551, it offers the same "Turbo" CAN as the HVD255 even if it's not explictly stated in the datasaheet? Turbo CAN is more of a trademark than a standard? Are there software constraints or requirements if I want to have Turbo CAN functionality? 

    In fact, I'm just thinking, what I need is adatable baudrate based on bus load. Maybe it's called Turbo CAN or maybe I'm just mixed up in the terminology. I see Flexible Data Rate (FD) in the HVDA datasheet but not in the HVD255..

    Can you differentiate Turbo CAN and Flexible Data Rate for me?

    Thanks!

  • 0 in reply to mosin
    TI__Mastermind 21911 points

    Hi Mosin,

    I apologize, I did mean J1939! I have been working with the J2962 standard, and it must have still been on my mind.

    The "Turbo" CAN is a trademark of a TI technology that we put into our transceiver for the fast propagation delays and symmetric bit timing. This is different that CAN FD. CAN with Flexible Data-Rate (FD) is a new CAN standard that Bosch has proposed which adds the ability to have larger payloads and two different bit times for the frame. There will be one bit time used for the arbitration and a portion of the control field and there is the ability to switch to a faster bit time for the data portion of the frame where the two-way loop time is no longer important in the operation of the CAN network.

    So in summary, Turbo CAN is a the technology TI uses in their transceivers, and CAN FD is a new proposed CAN standard that Bosch has created. The Turbo CAN technology actually plays into the new CAN FD standard quite well.

    In terms of adaptable baud rate, do you want the dominant edge drive strength to vary depending on the data rate of the communication? If so, why do you have the need for that? Are you concerned about emissions?

    Thanks,

    John

  • 0 in reply to John Griffith
    Expert 1160 points

    Hi John,

    That makes sense! When you wrote back, I was reading on the new standard from Bosch, CAN FD. I understand that this has "big" software impact. The controller needs to support this. As for the drive strength, I'm not aware that we need variable drive strength depending on the data rate. I just received instructions to look for Turbocan mixed with CAN network load.

    I'll keep reading about all this. If I need something else, I'll drop by later!

    Thanks  

  • 0 in reply to mosin
    Expert 1160 points

    Hi John,

    What are the main big differences between HVDA551, HVD251 and HVD255? I was trying to compare characteristics to see where the turbo can technology comes into account but I can't seem to find big differences. 

    Also, for the HVDA551, it says it supports CAN FD but with 1Mbps maximum data rate. So, the only part it supports about CAN FD is the different data rate between arbitration and actual data payload?

    Lastly, about the HVD255 caracteristic : Fast loop times for highly loaded networks. Does the module really do something or is it the software that needs to detect bus load and vary the data rate according to it?

    Thanks a lot!

  • 0 in reply to mosin
    TI__Mastermind 21911 points

    Hi Mosin,

    Good questions!

    Let me start with the HVDA551-Q1. Since FD CAN has been such a hype, it was important to mention that the transceiver is capable of flexible data-rates. With CAN FD, your current CAN network could be communication at 125KBPS standard CAN. Let's say you upgraded the micro-controllers and continued to use 125KBPS for the arbitration field, but then switch to a higher data-rate, let’s say 500KBPS, for the data field. You would be using the device for flexible data-rate CAN and under the 1MBPS limit.  The reason this device has 1MBPS data-rate is because that is how far we characterized it across process, voltage and temperature. We would have to re-characterize the device for higher data-rates before guaranteeing higher speeds in the datasheet. CAN FD only requires the micro-processor to change with speeds under 1MBPS.

    The SN65HVD251 is an older industrial CAN transceiver that was released over 10 years ago. It does not have our latest turbo CAN driver technology but still operates up to 1MBPS. It can also be used for FD CAN applications under 1MBPS.

    The SN65HVD255 device is the latest industrial CAN transceiver family that we have that we pushed the Turbo CAN technology on. Again this is just a new way we built the driver circuitry and it plays nicely into the FD CAN standard. We are currently releasing SN65HVD26x devices that will be characterized to operate up to 2MBPS. There is no software feedback needed for the driver to operate up to 2MBPS, it is optimized on the transceiver itself.

    Thanks,

    John

  • 0 in reply to John Griffith
    Expert 1160 points

    Hi John,

    Thanks for the clear answer. That helps me alot. 

    Two things that are still unclear. What about the Fast loop times for highly loaded networks. Is it something only present in the HVD255 or is it also present in the HVDA551? WIll the HVD26x be automotive certified? 


    Thanks!

  • 0 in reply to mosin
    TI__Mastermind 21911 points

    Hi Mosin,

    Sorry for the delay in getting back to you. The Turbo CAN technology is what enables the device to have the fast loop times for highly loaded networks. Therefore the HVDA551-Q1, HVDA553-Q1 and SN65HVD255 all have this.

    I do not believe we will be automotive qualifying the SN65HVD26x devices since we are beginning the development of our next generation automotive CAN devices.

    Thanks,

    John

  • 0 in reply to John Griffith
    Prodigy 90 points

    Hi John,

    You mentioned: "we are beginning the development of our next generation automotive CAN devices."

    It has been a couple year since this post, has the next generation come out yet?

    -or-

    What are the latest and greatest chips to use for a J1939 application?

    Thanks,

    Tony

  • 0 in reply to Tony Demico
    TI__Guru 62920 points
    Hi Tony,

    The new devices are currently sampling and are close to release. If you send me a note at m(hyphen)robertson(at)ti(dot)com I could give you some more information.

    Regards,
    Max