STM32G0 internal temperature sensor

[emre ozdemir]

Hello All,

I need to read tempereture of mcu.

But I confused about formula given at referance manual.which is below.Because there no data TS_CAL_2 val

 

 

Thanks.

Regards.

EMRE

[Imen.D]

Hello @emre ÖZDEMİR​ ,

There is a internal request to update the formula in the coming releases of the RM0454.

In the meantime, you can refer to the formula provided in RM0360:

 

When your question is answered, please close this topic by choosing Select as Best. This will help other users find that answer faster.

Thanks

Imen

[emre ozdemir]

Hello,

I tried the formula given in RM0360,code example actually.I updated address and ADC data in the formula.But temperature value I get is not realistic.

/* Temperature sensor calibration value address */

#define TEMP30_CAL_ADDR ((uint16_t*) ((uint32_t) 0x1FFF75A8))

#define VDD_CALIB ((uint32_t) (3300))

#define VDD_APPLI ((uint32_t) (3000))

#define AVG_SLOPE ((uint32_t) (5336)) // AVG_SLOPE in ADC conversion step (@3.3V)/°C multiplied by 1000 for precision on the division

int32_t temperature; /* will contain the temperature in degrees Celsius */

temperature = ((uint32_t) *TEMP30_CAL_ADDR - ((uint32_t) ADC_TEMPERATURE * VDD_APPLI / VDD_CALIB)) * 1000;

temperature = (temperature / AVG_SLOPE) + 30;

Thanks.

EMRE

[emre ozdemir]

Hello ,

It is an ergent stuation.

Is there any suggestion for me.

Thanks.

EMRE

[waclawek.jan]

Which STM32 exactly?

What hardware? Is this a "known good" board such as Nucleo or DIsco, or your own design? If the latter, how is VDDA/VREF+ connected?

> .But temperature value I get is not realistic.

Post numbers - the raw ADC readout, actual VREF/VDDA voltage, readout of the calibration value.

Do you observe the start time and the sampling time given for temperature sensor in the datasheet?

JW

[emre ozdemir]

Hello,

This board is our custom design.

Here the values

Raw ADC data at

tempereture channel = 1005

Vref = 1540

*TEMP30_CAL_ADDR = 1042;

*VREFINT_CAL = 1659

adcData[2] stores temperature channel value

adcData[3] stores vref channel value

here is the code for temperature

void CalculateTemperature(void)

{

if(temperatureReadTime++ == 100)

{

temperatureReadTime = 0;

temperature = ((uint32_t) *TEMP30_CAL_ADDR - ((uint32_t) adcData[2] * VDD_APPLI / VDD_CALIB)) * 1000;

temperature = (temperature / AVG_SLOPE) + 30;

if(temperature > TEMPERATURE_THRESHOLD && MOTOR_ERROR == 0)

{

MOTOR_ERROR = 1;

MOTOR_STOP();

}

}

}

here is the code for vref (I get this formula from datasheet)But this also gives me (around 2.78V) from the calculation.

void CalculateVref(void)

{

if(VrefReadTime++ == 100)

{

VrefReadTime = 0;

Vref = 3.00 * ((double)adcData[3] / *VREFINT_CAL);

}

}

About sampling time when I check the datasheet

Here is the conversation time formula

for temperature minimum value is 5 ms

 

ADC clock speed is 16 mHz.

And ADC clock prescaler is 10

Sampling time 160.5

if I calculate the time (160.5+12.5)/(16MHZ/10) = 108 us.This should be suitable then.

There is not a info about a certain sampling time to read temperature.

Thanks.

EMRE

[S.Ma]

In case this snippet helps.

Make sure adc conversion is longest time, and channel for vref/vtemp are powered up

int32_t Interpolate_s32 (int32_t x0, int32_t x1, int32_t y0, int32_t y1, int32_t x) {
 
  int32_t dwQ;
 
  dwQ = ((y1-y0))*x+(x1*y0)-(x0*y1);       // overflow not checked yet
 
  dwQ = dwQ / (x1-x0);// we can also do roundings here
 
  return dwQ;
 
}
 
int32_t Deg30Lsb;
 
  int32_t Deg130Lsb;
 
  int32_t ADC_Num, ADC_Denum;
 
  int32_t DegC_x10;
 
int32_t ADC_Convert_mV_to_DegC_x10(ADC_t* A, uint32_t Lsb) {
 
  Deg30Lsb = (int32_t)(*((uint16_t*) 0x1FFF75A8));  // 3.0V +/- 10mV
 
  Deg130Lsb = (int32_t)(*((uint16_t*) 0x1FFF75CA)); // 3.0V +/- 10mV
 
  // we first convert the LSB calibrated Flash values to mV (let's remove the sign issue between normal and injected channels)
 
  // convert ADC value to 3.0 Vdd vs measured value
 
  Lsb = (Lsb*A->MeasuredVdd_mV)/3000; // scale the LSB to 3.0V
 
  DegC_x10 = Interpolate_s32 (Deg30Lsb, Deg130Lsb, 300U, 1300U, (int32_t)(int16_t)Lsb);
 
  A->Temp_degC_x10 = DegC_x10; // capture the value for debugging or reference
 
  return DegC_x10;
}
 
 
 
int32_t ADC_Convert_VRefByLsb(ADC_t* A, uint32_t Lsb) {   // Vref = 1.212V
 
  int32_t VRefLsb3p3V_Lsb = (int32_t)(*((uint16_t*) 0x1FFF75AA)); // this contains the ADC 12 bit right aligned raw data for Vref LSB at 30C and 3.0V
 
  uint32_t Vdd_mV = (3000*VRefLsb3p3V_Lsb)/Lsb;
 
  A->MeasuredVdd_mV = Vdd_mV;
 
  return 0;
}

[emre ozdemir]

Hello,

stm32g030 does not have a 130°C calibration value.

So I could not implement this script into my code.

Thanks.

EMRE

[waclawek.jan]

Which STM32, exactly?

> here is the code for vref (I get this formula from datasheet)But this also gives me (around 2.78V) from the calculation.

>[...]

> Vref = 3.00 * ((double)adcData[3] / *VREFINT_CAL);

No, it's the other way round, Vref = 3.00V * (*VREFINT_CAL) / adcData. That gives Vref = 3.23V.

What is the actually measured voltage at VREF+ pin?

From this, voltage at your temperature sensor is Vref*1005/4096=3.23V*1005/4096=0.793V

The calibrated 30deg. voltage is 3.00V*1042/4096=0.763V, so your voltage is 30mV higher. Given average slope 2.5mV/deg, this is equivalent to 30mV/2.5mV/deg.C=12deg.C, i.e. internal die temperature 30deg+12deg=42deg. IMO entirely plausible.

JW

[S.Ma]

Sharpen your problem solving skills, if you have only one reference point and a slope in lsb per degree, you can calculate 130 degree point as 100 degtee shift and keep the code almost the same as with stm32 with 2 points. Say 341 lsb more at 130 degree vs 30 degree....

Deg130Lsb = Deg30Lsb + 341; // read your stm32 spec and tune.