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INA228-Q1: Facing issues in reading Current, Energy, power, charge with INA228

Embedded Developer
Intellectual 375 points
Part Number: INA228-Q1
Other Parts Discussed in Thread: INA228

Tool/software:

I am facing issues in reading some parameters in INA228. Current, power, energy and charge registers are zero. I am able to read the shunt voltage and the voltage being read is within the range. There is one more observation regarding this, MATHOF flag is 1(even after clearing ACC registers on every program reset)

  • +1
    TI__Mastermind 27470 points

    Hello,

    From this information, it seems that you don't have the SHUNT_CAL register programmed. See section 8.1.2 of the datasheet for the equations.

    With the SHUNT_CAL register at 0, all results that use CURRENT_LSB will read 0 (ie, current, power, energy and charge), and you would have the MATHOF flag as well. If you do have a value in the register, then you will still read 0 and have the MATHOF error if you are measuring a current higher than the "Maximum Expected Current" used in equation 3.

  • 0 in reply to Mitch M
    Intellectual 375 points

    Hi,

    I checked SHUNT_CAL register, the value being written is 2500. Also, the mathOF = 1 and CNVRF = 1 happens together. No current is being flown and Vshunt = -0.00242187502mV. 

    The issue still persists

  • 0 in reply to Embedded Developer
    TI__Expert 6100 points

    Thank you for your patience. Mitch is currently out of the office and will reply when he returns on 8/25.

  • 0 in reply to Embedded Developer
    TI__Mastermind 27470 points

    Hello,

    Ok, so it does look like you are seeing the MATHOF error, but I'm not sure why yet, since your SHUNT_CAL has a value in it and you have no current. Can you send me a readout of all register values during the MATHOF error? Also, can you let me know your shunt resistor size, and the maximum current you used for calculating the CURRENT_LSB, and the CURRENT_LSB you used, if different from the calculated value. 

    Also, are you seeing this on more than one board/device? Or just this one device and board combination?

    Regards,

    Mitch