Internal temperature sensor

[josescxavier]

I'm trying to read the internal temp sensor of a STM32F030F4Px but datasheet isn't clear about how to calculate it.

Vsense = ( 1686 / 4095 ) * 3.3 = 1.35V

Temp = ((1.43 - 1.35) / 4.3 ) + 30 = 30.01C

In the code example it isn't any clear because I got:

ADC1->DR = 1686

TEMP30_CAL_ADDR = 1770

VDD_CALIB = VDD_APPLI = 3300

temp = (1770-1686) * 1000 = 84000

temp = 84000/4300 +30 = 49.5C

Actual room temperature is 22C.

What am I doing wrong?

thank you

[S.Ma]

You measure the plastic packaged sealed silicon chip temperature.

Because it drains current to operates, it is a heat generator.

The measured internal temp would match ambiant just after the chip is cold powered up, assuming SW would be bug free...

[Rogers.Gary]

Assuming your address for stored values are correct, replace the ones below with yours and try this. Works well on STM32F4xx:

//stored calibration constants for STM32F4

#define TEMP30_CAL     ((uint16_t*) ((uint32_t) 0x1FFF7A2C))

#define TEMP110_CAL    ((uint16_t*) ((uint32_t) 0x1FFF7A2E))

           //perform temperature read using STM32F4 internal sensor

           ADC_SoftwareStartConv(ADC1); //Start the conversion

           while (ADC_GetFlagStatus(ADC1, ADC_FLAG_EOC) == RESET);

           uint16_t TS_DATA = ADC_GetConversionValue(ADC1);

           // factory calibration coefficients stored at macro pointer locations

           float32_t tmp = (float32_t) ((( (110 - 30)*(TS_DATA - *TEMP30_CAL) ) / (*TEMP110_CAL - *TEMP30_CAL) ));

[josescxavier]

How do you justify the difference result on both methods?​

[josescxavier]

I don't think I have that temp110 Cal value​

[Rogers.Gary]

Check page 743 of the reference manual, there's an example there.

[Mohamed Aymen HZAMI]

Hello,

The temperature sensor inside the chip is dedicated to the measurement of silicon temperature.

Best Regards,

Mohamed Aymen.