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BQ76952EVM: BQ7695204 comms with EVM via SPI

Nick
Intellectual 612 points
Part Number: BQ76952EVM
Other Parts Discussed in Thread: BQSTUDIO, BQ76952,

I successfully changed the comms protocol from I2C to SPI on EVM board. 

I have ordered Bq7695204 IC for my project. Now I am trying to communicate with BQ7695204 IC using MCU on EVM. But not able to do so. When I open BQstudio , nothing comes.  I am using attached diagram. Please suggest. 

  • 0
    TI__Guru 54715 points

    Hi Nitin,

    Much like a data sheet simplified schematic which may not show all components it is hard to know what is really connected from your simple diagram.

    REG18 needs a capacitor for the part to operate.

    The BQ76952 must have a signal to wake up after power is applied, either LD or pull down on TS2.  On the EVM the ESD capacitors will bias LD when the supply is enabled.  Be sure some signal is applied on your part.  Check that REG18 has 1.8V.

    Your diagram shows SPI_CS connected to GND (PACK-), the part needs to see the signal move to know when to frame the data.

    Be sure there is not a conflict with the part on the EVM.  The IC must be removed from the board if using J22, otherwise connect at the signals from the MCU at the selection jumpers.

    The connection to J29 pin 2 may be for a pull up, however the signal goes to the MCU RST signal, when MISO toggles it may affect the interface.

  • 0 in reply to WM5295
    Intellectual 612 points

    Thanks a lot, 

    I am able to communicate with BQ7695204 using MCU on BQ76952EVM and see results on BQSTUDIO

    One doubt I have. I connected "REG1 of BQ7695204" to REG1 pin at J2 connector on EVM.  I hope I am not damaging BQ76952 on EVM board. 

     

    PS: There is no supply on BAT+ / VSS on EVM board, so BQ76952 is off.  

  • +1 in reply to Nick
    TI__Guru 54715 points

    Hi Nitin,

    Connecting REG1 to another part is not advised.  It may bias internal paths, the abs max limit includes VREGIN+0.3.  Biasing REG1 may push up REGIN so it may be ok, but it would seem to violate the specification so it could be damaged.