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BQ79731-Q1: BQ797xx VIF Daisy Chain Simulation

Gabe Ferencz
Prodigy 10 points
Part Number: BQ79731-Q1
Other Parts Discussed in Thread: USB2ANY

Tool/software:

I'm looking to test BMS boards with production firmware. The BMS board has an on-board BQ79731-Q1 and expects to talk to 8 off-board BQ79718's over the VIF daisy chain. I'm hoping to be able to connect something to the VIF interface that can simulate being the chain of BQ79718's and be able to respond with programmatically assigned voltages/temperatures.

My first attempt was a BQ79718 eval board. I tried to use the eval board to translate the VIF to the UART using a USB2ANY, but was not able to get the UART mirror mode working. I suspect that was because the BQ79731 is already acting as the base device. I also tried a BQ79600, but was also unable to get the VIF requests passed through to the UART. I suspect that's because the BQ79600 is expecting to be the base device and I was trying to use it the other way around.

So, unless the eval boards are capable of forwarding the VIF messages to the UART and I just configured them incorrectly, I'm looking at other ways I can simulate the BQ79718 chain. A custom board that bit-bangs the VIF interface is not off the table, but I'm hoping for something more COTs than that. Has any successfully set up a simulator for the BQ797xx VIF daisy chain?

  • 0
    TI__Intellectual 1850 points

    Hi Gabe,

    Regarding UART mirror mode, the stack device will only mirror response frames, not any received command frames.

    To simulate a stack of BQ79718, there would have to be an external device that receives VIF command frame, to send VIF response frame back to the base device

    Best Regards,

    John

  • 0 in reply to John Du
    Prodigy 10 points

    Thanks John. That's what I was afraid of with the BQ79718 eval board. It also seems like the BQ79600 is not able to be configured to forward VIF commands back to the UART.

     Are there any TI parts that would take in VIF command frames and be able to send back the response? Would perhaps something with an RS-485 transceiver be capable of the simulation?

  • 0 in reply to Gabe Ferencz
    TI__Intellectual 1850 points

    Hi Gabe,

    Transceivers could be something to look into. However, this would be out of scope of BMP support. Any issues with interacting with BQ797XX and BQ796XX devices feel free to ask.

    Best Regards,

    John