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INA230: Read the shunt register value by default is 0xffff

xiongzz
Prodigy 10 points
Part Number: INA230


Tool/software:

Hello Sir, 

I'm confused about the shunt register:

The registers can be configured, I2C communication is also correct, but why I read the shunt register value is 0xffff even by default. Meanwhile, I measured with a multimeter that the voltage drop across the shunt resistor was about 1mV.

What causes this problem and how to fix it?

Thanks.

Xiongzz

  • +1
    TI__Mastermind 26745 points

    Hello Xiongzz,

    The current result from the INA230 is in 2's compliment, so if the value is near 0V, you could be reading a slightly negative value, for example, -1LSB would show as 0xFFFF. So this makes sense for a default value with no current. When you do have a current, try measuring right at the IN+ and IN- pins of the device instead of the resistor just to confirm that you are measuring the same voltage the INA is seeing.

    Regards,

    Mitch