Solved
Reading the temperature sensor of an STM32H753
When reading the temperature sensor of an STM32H753, I read above 65 °C, right at start-up. The board lays on the desk, and the MCU doesn't feel that warm, maybe up to 36 °C.
The environmental temperature now, is about 24 °C.
After a some time, the MCU temperature increases to above 85 °C.
The reading seems somewhat high, to me. Below is the code I used.
Update: I added the call to the ADC calibration function.
HAL_ADCEx_Calibration_Start(&hadc3, ADC_CALIB_OFFSET, ADC_SINGLE_ENDED);Below updated code, which now reads reasonable values:
#define TS_CAL1_REG 0x1FF1E820 // Calibration ADC value at 30 °C
#define TS_CAL2_REG 0x1FF1E840 // Calibration ADC value at 110 °C
#define TEMPERATURE_ADC_SAMPLES 8
uint16_t MCU_Temperature_AVG = 50;
uint16_t TemperatureCalculate(uint32_t ts_data)
{
// 0x1FF1E820 Calibration ADC value at 30 °C = 0x2fc0, 12224
uint16_t ts_cal1 = *(uint16_t*) (TS_CAL1_REG);
// 0x1FF1E840 Calibration ADC value at 110 °C = 0x3cb4, 15540
uint16_t ts_cal2 = *(uint16_t*) (TS_CAL2_REG);
return (80 * (ts_data - ts_cal1)) / (ts_cal2 - ts_cal1) + 30;
}
void TemperatureStart(void)
{
// To get reasonable results of 50-60 °C when the system is heated up,
// we need to call the calibration function before starting the ADC:
HAL_ADCEx_Calibration_Start(&hadc3, ADC_CALIB_OFFSET, ADC_SINGLE_ENDED);
// Perform first reading to adjust average value
HAL_ADC_Start(&hadc3);
if (HAL_ADC_PollForConversion(&hadc3, 1000000) == HAL_OK)
{
MCU_Temperature_AVG = TemperatureCalculate(HAL_ADC_GetValue(&hadc3));
}
HAL_ADC_Stop(&hadc3);
HAL_ADC_Start_IT(&hadc3);
}
int16_t TemperatureRead(void)
{
// Temperature (°C) = ((110 - 30) * (TS_DATA - TS_CAL1)) / (TS_CAL_2 - TS_CAL_1) + 30
// Where:
// • ts_cal1: temperature sensor calibration value at 30 °C, VDDA= 3.3 V
// • ts_cal2: temperature sensor calibration value at 110 °C, VDDA= 3.3 V
// • ts_data: temperature sensor output from ADC
// Temperature (°C) = 80 * (ts_data - ts_cal1) / (ts_cal2 - ts_cal1) + 30
// ts_cal1 = T1_30 = at 30 Degrees
// ts_cal2 = T2_110 = at 110 Degrees
uint16_t MCU_Temperature_New = TemperatureCalculate(HAL_ADC_GetValue(&hadc3));
// Average temperature reading
// One part new value + 7 parts old value is 8 parts in total
uint16_t MCU_Temperature = MCU_Temperature_New + MCU_Temperature_AVG * (TEMPERATURE_ADC_SAMPLES - 1);
// Divide by 8
MCU_Temperature_AVG = MCU_Temperature / TEMPERATURE_ADC_SAMPLES;
if (HAL_ADC_Start_IT(&hadc3) != HAL_OK)
{
/* Start Conversation Error */
// dmc_puts("HAL_ADC_Start\n");
}
return MCU_Temperature_AVG;
}
int16_t TemperatureGet(void)
{
return MCU_Temperature_AVG;
}
/**
* @brief This function handles ADC3 global interrupt.
*/
void ADC3_IRQHandler(void)
{
/* USER CODE BEGIN ADC3_IRQn 0 */
(void) TemperatureRead();
/* USER CODE END ADC3_IRQn 0 */
HAL_ADC_IRQHandler(&hadc3);
/* USER CODE BEGIN ADC3_IRQn 1 */
/* USER CODE END ADC3_IRQn 1 */
}
print("Temperature: %d C\n", TemperatureGet());Am I doing something wrong?
