MSPM0G3507: Variations and deviations in temperature measurement

Hi Sebastian, 

Can you give the  DL_SYSCTL_getTempCalibrationConstant() return value?

B.R.

Zoey

Here are the calibration values:

1. 756
2. 763
3. 755
4. 757
5. 752

Best Regards,

Sebastian

 Hi Sebastian,

The trim value seems to be correct. 

Have you tried to use demo code in SDK to have a try? ...\ti\mspm0_sdk_1_30_00_03\examples\nortos\LP_MSPM0G3507\driverlib\adc12_internal_temp_sensor_mathacl

Hi,

I just tried the example code you mentioned. I copied the code in my application and it looked like this:

    uint32_t       adcResult;
    _iq15          qVSample, qTsample, qVTrim;
    volatile float gTemperatureDegC;

    // store value for debug purpose
    m_AdcTemp = AdcTemp;

    adcResult = m_AdcTemp;

    /*
     * Convert TEMP_SENSE0 result to equivalent voltage:
     * Vtrim = (3.3*(TEMP_SENSE0 -0.5))/(2^12)
     */

    qVTrim = _IQ15div(
        _IQ15mpy((_IQ15(DL_SYSCTL_getTempCalibrationConstant()) - _IQ15(0.5)), _IQ15(3.45)), ((uint32_t)(1) << 27));

    /*
     * Convert ADC result to equivalent voltage:
     * Vsample = (VREF_VOLTAGE_MV*(adcResult -0.5))/(2^ADC_BIT_RESOLUTION)
     */

    qVSample = _IQ15div(_IQ15mpy((adcResult << 15) - _IQ15(0.5), _IQ15(ADC_VREF_VOLTAGE)), _IQ15(ADC_BIT_RESOLUTION));

    /*
     * Apply temperature sensor calibration data
     * TSAMPLE = (TEMP_TS_COEF_mV_C) * (qAdcResultV - vTrim) + TEMP_TS_TRIM_C
     */
    qTsample = _IQ15mpy(_IQ15(TEMP_TS_COEF_mV_C), (qVSample - qVTrim)) + (TEMP_TS_TRIM_C << 15);

    gTemperatureDegC = _IQ15toF(qTsample);

    m_Temperature = static_cast<int32_t>(gTemperatureDegC * 10);

This now runs on my hardware #5. And the result is 20.1°C.

• The temperature of 20.1°C is better than before. Like yesterday I measure it at room temperature and therefore I would expect a chip temperature of 25°C to 30°C?
• The calculation is based on a reference voltage for VTrim of 3.45V, which seems incorrect for me (see formula of qVTrim). If I change it to 3.3V I get a chip temperature of 3.2°C which is worse. What is right here?

Thanks,

Sebastian

Hi Sebastian,

I also find this strange code there. I will write e-mail to ask our system and software team. Once I get information, i will tell you.

Hi Zoey,

do you have any news for me regarding this issue?

Thanks,

Sebastian