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Original question:

[FAQ] BQ27Z758: What FW should I use on the BQ27Z758?

BQ27Z758: Does BQ27Z758 ship with default firmware

Dan Harrison
Prodigy 10 points
Part Number: BQ27Z758
Other Parts Discussed in Thread: EV2400,

Tool/software:

I am using the BQ27Z758 is a very space constrained environment.  I cannot easily provide a connection to an external EV2400.  Does the BQ27Z758 ship with default firmware already installed so that I can communicate with it exclusively via my local micro?  Also, is there any sort of code base available to run on an MSP430 to interface with the fuel gauges or do I have to create that from scratch?

  • 0
    TI__Mastermind 27405 points

    Hello,

    This question has been assigned and will be reviewed when possible.

    Thank you,
    Alan

  • 0 in reply to Alan Frias
    Prodigy 10 points

    I ask because I am, not even seeing an ACK to my 0xAA start on the I2C bus between my micro (MSP430G2553IRHB32R) and the gauge (BQ27Z758YAHR).  The only thing on the SDA / SCL lines besides these two parts are a pair of 10K pullups.

  • +1 in reply to Dan Harrison
    TI__Mastermind 25021 points

    Hello, 

    Yes the gauge is shipped with default FW. 

    Regards, 

    Jonny. 

  • 0 in reply to Jonny
    Prodigy 10 points

    Ok. Should I assume the default FW should ACK an I2C start to addr 0xAA (0x55 + R/W bit).  Any suggestions for why it wouldn't?

  • 0 in reply to Dan Harrison
    TI__Mastermind 25021 points

    Hello, 

    Make sure you have your comm lines pulled up to a 3.3V steady source. Are you using the EV2400? 

    Regards, 

    Jonny. 

  • 0 in reply to Jonny
    Prodigy 10 points

    I am using pullups (10K) to the VDD of the BQ27Z758.  I am not using the EV2400 as I cannot access the relevant signals internal to my system.  My only connection to the BQ27Z758 is via an embedded MSP430G2553IRHB32R which I am bit banging GPIO to the fuel gauge's I2C pins.  I have got the BQ27Z758 to ACK the address and even readout some registers - albeit with some unusual responses.  It appears the necessary action to gain I2C life was to  remove the connection from the /ENAB pin to GND.  Does that make any sense?  It would seem from the datasheet pin description and all the reference circuits that one should explicitly tie /ENAB to GND, so is it possible that pulling it high (or allowing it to float) is actually needed to achieve communication?  
    Can you elaborate on the function and ways to manage the /ENAB signal?

  • 0 in reply to Dan Harrison
    TI__Mastermind 25021 points

    Hello, 

    The ENAB pin should not have an effect on the comms. ENAB can be directly tied to gnd or can be left floating. The ENAB pin is only used to wake the device from low power modes. 

     Regards, 

    Jonny.