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# STM32H743 Internal CPU Temperature

Associate II

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,

13 REPLIES 13
Chief II

>Any ideas ?

No ... it has to work then. Just curious : you get 4x the expected value -- not any random thing. Hmmm...

Other test: if you convert any input from ADC pin, set to a known voltage, lets say: 1V at the pin, what you get then from ADC ?

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ST Employee

Hi @anasba

This post has been escalated to the ST Online Support Team for additional assistance.  We'll contact you directly.

Regards,

Billy

Associate II

Hey,

I'm facing similar issue on H743VIT6. Internal temperature is almost 10 times. Even the 3.3V sensing is wrong. I'm using the H743VIT6 rev V.

Associate II

I have an idea which might explain where the issue comes from.
Here are the details :

• The project is built on a STM32H743 .ioc project.
• The PCBA we use is a STM32H750.

Will that influence the CPU sensor calibration/acquisition ?
Many thanks