Reading ADC data for current sensing from DRV8301 bord.

Rahul Sharma

Expert 2725 points

Other Parts Discussed in Thread: DRV8301

Hi all,

I am reading ADC values of phase current sensors in DRV8301.

I did the following for that i made a function in hal.h

static inline CurrentSensorRead_A(HAL_Handle handle)

{

HAL_Obj *obj = (HAL_Obj *)handle;
int gIAread = 0;
gIAread = ADC_readResult(obj->adcHandle,ADC_ResultNumber_1);

return gIAread;

}

and i call that function inside while loop in project man function.

Is there a mistake i am doing? as in watch window the ADC values are fluctuating (say in between 2061-2072).

Thanks.

over 8 years ago

0 Yanming Luo over 8 years ago

TI__Guru** 115500 points

There is a 1.65V reference voltage for current signal, so the ADC result value should be about 2048 if the current is zero without running motor.

0 Rahul Sharma over 8 years ago in reply to Yanming Luo

Expert 2725 points

Hello Yanming,
Thanks for the reply.
Yes it should be 2048 value for 1.65V but i have 2 new boards and both are giving values (2060-2065), even when motor wires are not connected to the board.
What could be the problem?
Thanks.

0 Yanming Luo over 8 years ago in reply to Rahul Sharma

TI__Guru** 115500 points

Refer to DRV8301 datasheet, the reference voltage default is enable with 1.65V if the power is on, it does not depend on whether the motor is connected. Please measure the voltage of REF (=3.3V), SO1 (1.65V), SO2 (1.65V) using multi-meter.

0 Rahul Sharma over 8 years ago in reply to Yanming Luo

Expert 2725 points

Hi Yanming,
I checked DRV8301 voltages of REF, SO1, SO2 with multi-meter. These are exact 3.3V, 1.65V, 1.65V output values respectively.
But Still the ADC values at watch Window is showing 2062-2064.

Are these values are with offset values? Because motor behaviour is as expected, only doubt is that 2048 value is not being displayed.

Thanks.

0 Sean Bigley over 8 years ago in reply to Rahul Sharma

TI__Genius 17175 points

Errors in ADC readings can be from numerous sources - offset error, gain error, non-linearity error, noise error. If you see a constant offset over a wide range of reading with the exact same DC input, you can subtract that error out to "bias" it to your desired value

Sean

0 Rahul Sharma over 8 years ago in reply to Sean Bigley

Expert 2725 points

Ok Sean.

Thanks.

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Reading ADC data for current sensing from DRV8301 bord.