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BQ27530-G1: Not Responding

Anthony Cicala
Prodigy 20 points
Part Number: BQ27530-G1
Other Parts Discussed in Thread: BQSTUDIO, EV2400, BQ27531-G1

I'm having trouble trying to get the IC to respond. I realize that I connected Vss to the battery ground instead of the device ground. Would this be the reason for my device not acknowledging?

  • 0
    TI__Guru** 102375 points

    Hello Anthony,

    Can you check the REGIN and CE pins to make sure the gauge is enabled and powered?

    Having the ground different should not matter, unless you have low side protection that is disabling the PGND.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    Hi Wyatt

    I can't probe the pins directly but the input cap on that pin is connected to the battery. This is what SDA and SCL look like when trying to address the chip and there seems to be no acknowledge

  • 0 in reply to Anthony Cicala
    TI__Guru** 102375 points

    Hello Anthony,

    The gauge is either not getting power or it is damaged. From your schematic and cannot tell where the other power nodes are connected.

    Are you using bqStudio to communicate with the gauge?

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    I am not using bqstudio to communicate. We are communicating with the device through a Nordic IC.

    Also, I probed the BI/TOUT pin and it was at 2.6V, so I assume that the chip is being powered but I don't know. Does this seem like a normal operational voltage for that pin?

  • 0 in reply to Anthony Cicala
    TI__Guru** 102375 points

    Hello Anthony,

    Make sure the gauge is not is ROM mode as well, if you had just programmed it it may still be in ROM mode.

    Without the measurements on CE and REGIN it will be hard to know the state of the guage is. I would also try using the EV2400 since it should also detect if it's in ROM it will readout fffff_ffffff as the device version. You will need an EV2400 regardless to program the chem ID.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    What is ROM mode? I did not see that in the datasheet.
    "I would also try using the EV2400 since it should also detect if it's in ROM it will readout fffff_ffffff as the device version". We aren't able to get any response from the IC at all. The IC is giving a NACK to the initial address byte of the I2C transmission. 

  • 0 in reply to Anthony Cicala
    TI__Guru** 102375 points

    Hello Anthony,

    It is briefly mentioned in the BQ27531-G1 TRM: https://www.ti.com/lit/pdf/sluua96

    ROM mode is used for programming the gauge, in ROM mode the device address changes to 0x16, not 0xAA, if you try to communicate with 0xAA while in ROM it will NACK the address.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    We tried changing the address to 0x16 but we are still receiving NACK on the address byte. 

  • 0 in reply to Anthony Cicala
    TI__Guru** 102375 points

    Anthony,

    It sounds like the gauge is not powered or it is damaged/corrupted from the information you have available.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 20 points

    Hi Wyatt,

    We are able to get the IC to acknowledge i2c messages now, but we are running into other issues. It looks like the IC is performing some sort of clock stretching techniques, but this is confusing the micro. Can you confirm from these screenshots of the sda and scl lines what is happening/is there anyway to suppress clock stretching on the IC? The datasheet makes it sound like clock stretching is a non-configurable characteristic of the device. There will be a screenshot of a full sequence of messages followed by zoomed in screenshots of individual message for visibility. The sequence of messages is an attempt to read the voltage register of the device. Thanks.

  • 0 in reply to Anthony Cicala
    TI__Guru** 102375 points

    Hello Anthony,

    All of our guages uses clock stretching in order to fetch data the host requests, the host/driver used must be compatible with clock stretching.

    You can see in the BQ27531 TRM there is more information about clock stretching that is applicable: 8.4 I 2C Clock Stretching

    https://www.ti.com/lit/pdf/sluua96

    Clock stretching is not configurable, some of our newer gauges only give the option for the gauge to NACK if it is busy for too long, but it will still clock stretch.

    Sincerely,

    Wyatt Keller