Shimmer3R Calibration: division by 4095 or 16383

[czy10383]

    protected double CalibrateMspAdcChannel(double unCalData)
    {
        double offset = 0; double vRefP = 3; double gain = 1;
        double calData = CalibrateU12AdcValue(unCalData, offset, vRefP, gain);
        return calData;
    }

    protected double CalibrateShimmer3RAdcChannel(double unCalData)
    {
        double offset = 0; double vRefP = 3; double gain = 1;
        double calData = CalibrateU12AdcValue(unCalData, offset, vRefP, gain);
        return calData;
    }

    protected double CalibrateU12AdcValue(double uncalibratedData, double offset, double vRefP, double gain)
    {
        double calibratedData = (uncalibratedData - offset) * (((vRefP * 1000) / gain) / 4095);
        return calibratedData;
    }

    protected double CalibrateU14AdcValue(double uncalibratedData, double offset, double vRefP, double gain)
    {
        double calibratedData = (uncalibratedData - offset) * (((vRefP * 1000) / gain) / 16383);
        return calibratedData;
    }

I refer to the above codes in ShimmerBluetooth.cs Line 7496 onwards

When we call CalibrateShimmer3RAdcChannel for Shimmer3R, it will call CalibrateU12AdcValue which divides the data by 4095 as shown above.

Shouldn't it call CalibrateU14AdcValue which will divde the data by 16383 instead?

thank you

[JongChern]

hi @czy10383 I can confirm that the 3R uses a 12 bit ADC. do let me know if there is any info which might have caused the confusion and we will correct it.

[czy10383]

' int bitMask = 4095;
if (HardwareVersion == (int)ShimmerBluetooth.ShimmerVersion.SHIMMER3R)
{
bitMask = 16383;
}

                //double p1 = 0, p2 = 0;
                if (GSRRange == 4)
                {
                    newGSRRange = (49152 & (int)datatemp) >> 14;
                }
                datatemp = (double)((int)datatemp & bitMask);'

Hi @JongChern , thanks for your reply

My original question came about due to the above code in ShimmerBluetooth.cs in line 4176 onwards: if it is 3R, the bitMask = 16383 and not 4095. And at the end, datatemp = (double)((int)datatemp & bitMask)

Meanwhile CalibrateU12AdcValue (that uses 4095) is always called regardless it is 3R or not. Hence I was wondering if CalibrateU14AdcValue (thats uses 16383) should be called if it is 3R.

thank you