STM32H743 Internal CPU Temperature

[anasba]

Hello, I am trying to calculate the internal CPU temperature on an STM32H743, When reading the internal CPU temperature sensor using ADC3 IN18 (internal temperature), I get a very high value (~731C)
The formula I'm using is the following :

Temperature (in °C) = (110 °C – 30 °C) / (TS_CAL2 – TS_CAL1) * (TS_DATA – TS_CAL1) + 30 °C

Here is the algorithm to read the temp :

1. Initialise ADC3 
2. Calibrate ADC3
3. ADC3 Start DMA "Reading ADC3 values via DMA, Temperature sensor values are inside ADC_CHANNEL_TEMPSENSOR rank 11"
4. Start TIM6 (PSC = 10, ARR=59999) for the sampling frequency of the ADC3,  and the samplingTime is  810.5
5. Calculate TS_CAL1, TS_CAL2 
6. Convert ADC value to C°

Here is the code :

MX_ADC3_Init();
HAL_ADCEx_Calibration_Start(&hadc3,ADC_CALIB_OFFSET_LINEARITY, ADC_SINGLE_ENDED);
HAL_ADC_Start_DMA(&hadc3, (uint32_t *)&DMABuff[0], 11);
HAL_TIM_Base_Start_IT(&htim6);

const uint16_t* ADC_TEMP_3V3_30C = (uint16_t*)(0x1FF1E820);
const uint16_t* ADC_TEMP_3V3_110C = (uint16_t*)(0x1FF1E840);

float adcCalTemp30C = (float) (*ADC_TEMP_3V3_30C);
float adcCalTemp110C = (float) (*ADC_TEMP_3V3_110C);

float32_t Temperature = (110  – 30 ) / (adcCalTemp110C – adcCalTemp30C ) * (DMABuff[10] – adcCalTemp30C ) + 30;
I don't know if I missed something that has to be included?
Kind regards
Anas,

[AScha.3]

Hi,

did you set Tsen ?

[anasba]

Hello, thanks for the reply 
Yes indeed I set the TSEN with the following : 
ADC3_COMMON->CCR |= ADC_CCR_TSEN;
And then I run the calibration 

[anasba]

@AScha.3 It is still showing the same output even thought I enabled TSEN 

ADC3_COMMON->CCR |= ADC_CCR_TSEN;
HAL_ADCEx_Calibration_Start(&hadc3,ADC_CALIB_OFFSET_LINEARITY, ADC_SINGLE_ENDED);

Any ideas ? 
many thanks

[AScha.3]

What values you get from ADC real ? (in hex)

[anasba]

Dear @AScha.3,
With the following ADC value inside DMABuff (0x7f08): 

I get

1. Temperature = 734 C°
2. ADC (in mV) = 2413.89 
3. adcCalTemp30C = 13 820
4. adcCalTemp110C = 18 233

[AScha.3]

>ADC (in mV) = 2413.89

from ds :

-> thats about 4x the value you should get !

So whats your VDDA + Vref ?

+

In Cube, adc setup, you set to : 16bit , no oversampling, no shift ?

[anasba]

@AScha.3, appreciate the fast replies

I define :
CALIBRATION_REFERENCE_VOLTAGE as 3.3V
REFERENCE_VOLTAGE 3.0V // supplied with Vref+ or VDDA

Then : 
adcCalTemp30C = (float) (*ADC_TEMP_3V3_30C) / (REFERENCE_VOLTAGE/CALIBRATION_REFERENCE_VOLTAGE);

adcCalTemp110C = (float) (*ADC_TEMP_3V3_110C) / (REFERENCE_VOLTAGE/CALIBRATION_REFERENCE_VOLTAGE);

And also here is how I set the ADC3 in Cube 

[AScha.3]

So whats your AVDD and  VREF+  ? check with DMM at the connected pins. 

+ 

Try ADC settings : overrun data overwritten .

[anasba]

@AScha.3 
I've checked VREF+ and VDD with DMM 

VREF+ = 3.0 V

VDD = 3.36 V

I've changed the ADC settings  to OVERRUN DATA OVERWRITTEN with :
hadc3.Init.Overrun = ADC_OVR_DATA_OVERWRITTEN;
and it didn't fix it  
Any ideas ?