Where is the calibration data for the Temperature sensor in the STM32G031?
RM0444 Rev 5 Page 377 says
• TS_CAL2 is the temperature sensor calibration value acquired at TS_CAL2_TEMP
(refer to the datasheet for TS_CAL2 value)
• TS_CAL1 is the temperature sensor calibration value acquired at TS_CAL1_TEMP
(refer to the datasheet for TS_CAL1 value)
• TS_DATA is the actual temperature sensor output value converted by ADC
Refer to the specific device datasheet for more information about TS_CAL1 and
TS_CAL2 calibration points.
So I need to find TS_CAL1, TS_CAL2, TS_CAL2_TEMP, and TS_CAL1_TEMP
I go to DS12992 Rev 2 Page 24 Paragraph 3.14.1:
The temperature sensor (TS) generates a voltage V TS that varies linearly with temperature.
The temperature sensor is internally connected to an ADC input to convert the sensor
output voltage into a digital value.
The sensor provides good linearity but it has to be calibrated to obtain good overall
accuracy of the temperature measurement. As the offset of the temperature sensor may
vary from part to part due to process variation, the uncalibrated internal temperature sensor
is suitable only for relative temperature measurements.
To improve the accuracy of the temperature sensor, each part is individually factory-
calibrated by ST. The resulting calibration data are stored in the part’s engineering bytes,
accessible in read-only mode.
Table 5. Temperature sensor calibration values
Calibration value name Description Memory address
TS_CAL1
TS ADC raw data acquired at a
temperature of 30 °C (± 5 °C),
V DDA = V REF+ = 3.0 V (± 10 mV)
0x1FFF 75A8 - 0x1FFF 75A9
TS_CAL2
TS ADC raw data acquired at a
temperature of 130 °C (± 5 °C),
V DDA = V REF+ = 3.0 V (± 10 mV)
0x1FFF 75CA - 0x1FFF 75CB
So two of the 4 values I need are given in the documentation.
So I go to the CODE.
I Search for TS_CAL1, TS_CAL2, TS_CAL2_TEMP, TSCAL1_TEMP Not to be found except in a comment for a Macro that calculates a temperature based on their data. Found in stm32g0xx_ll_adc.h
/**
* @brief Helper macro to calculate the temperature (unit: degree Celsius)
* from ADC conversion data of internal temperature sensor.
* @note Computation is using temperature sensor calibration values
* stored in system memory for each device during production.
* @note Calculation formula:
* Temperature = ((TS_ADC_DATA - TS_CAL1)
* * (TS_CAL2_TEMP - TS_CAL1_TEMP))
* / (TS_CAL2 - TS_CAL1) + TS_CAL1_TEMP
* with TS_ADC_DATA = temperature sensor raw data measured by ADC
* Avg_Slope = (TS_CAL2 - TS_CAL1)
* / (TS_CAL2_TEMP - TS_CAL1_TEMP)
* TS_CAL1 = equivalent TS_ADC_DATA at temperature
* TEMP_DEGC_CAL1 (calibrated in factory)
* TS_CAL2 = equivalent TS_ADC_DATA at temperature
* TEMP_DEGC_CAL2 (calibrated in factory)
* Caution: Calculation relevancy under reserve that calibration
* parameters are correct (address and data).
* To calculate temperature using temperature sensor
* datasheet typical values (generic values less, therefore
* less accurate than calibrated values),
* use helper macro @ref __LL_ADC_CALC_TEMPERATURE_TYP_PARAMS().
* @note As calculation input, the analog reference voltage (Vref+) must be
* defined as it impacts the ADC LSB equivalent voltage.
* @note Analog reference voltage (Vref+) must be either known from
* user board environment or can be calculated using ADC measurement
* and ADC helper macro @ref __LL_ADC_CALC_VREFANALOG_VOLTAGE().
* @note On this STM32 series, calibration data of temperature sensor
* corresponds to a resolution of 12 bits,
* this is the recommended ADC resolution to convert voltage of
* temperature sensor.
* Otherwise, this macro performs the processing to scale
* ADC conversion data to 12 bits.
* @param __VREFANALOG_VOLTAGE__ Analog reference voltage (unit: mV)
* @param __TEMPSENSOR_ADC_DATA__ ADC conversion data of internal
* temperature sensor (unit: digital value).
* @param __ADC_RESOLUTION__ ADC resolution at which internal temperature
* sensor voltage has been measured.
* This parameter can be one of the following values:
* @arg @ref LL_ADC_RESOLUTION_12B
* @arg @ref LL_ADC_RESOLUTION_10B
* @arg @ref LL_ADC_RESOLUTION_8B
* @arg @ref LL_ADC_RESOLUTION_6B
* @retval Temperature (unit: degree Celsius)
* In case or error, value LL_ADC_TEMPERATURE_CALC_ERROR is returned (inconsistent temperature value)
*/
#define __LL_ADC_CALC_TEMPERATURE(__VREFANALOG_VOLTAGE__,\
__TEMPSENSOR_ADC_DATA__,\
__ADC_RESOLUTION__)\
((((int32_t)*TEMPSENSOR_CAL2_ADDR - (int32_t)*TEMPSENSOR_CAL1_ADDR) != 0) ? \
(((( ((int32_t)((__LL_ADC_CONVERT_DATA_RESOLUTION((__TEMPSENSOR_ADC_DATA__), \
(__ADC_RESOLUTION__), \
LL_ADC_RESOLUTION_12B) \
* (__VREFANALOG_VOLTAGE__)) \
/ TEMPSENSOR_CAL_VREFANALOG) \
- (int32_t) *TEMPSENSOR_CAL1_ADDR) \
) * (int32_t)(TEMPSENSOR_CAL2_TEMP - TEMPSENSOR_CAL1_TEMP) \
) / (int32_t)((int32_t)*TEMPSENSOR_CAL2_ADDR - (int32_t)*TEMPSENSOR_CAL1_ADDR) \
) + TEMPSENSOR_CAL1_TEMP \
) \
: \
((int32_t)LL_ADC_TEMPERATURE_CALC_ERROR) \
)So here it looks like they use TS_CAL1_TEMP in the equation, but call it TEMP_DEGC_CAL1 in the description of TS_CAL1
And they do the same with TS_CAL2_TEMP calling it TEMP_DEGC_CAL2
Unfortunately I cannot find
TEMP_DEGC_CAL1
TEMP_DEGC_CAL2
defined ANYWHERE in the code either.
So how are we supposed to do this?
