Posted on February 06, 2018 at 01:23
Hi,
I would like someone to confirm that the temperature I am getting is somewhat in the ballpark to be expected. If it isn't, could someone check my values that I am using from the datasheet?
I am currently getting 11 C which seems low for ambient room temperature.I know that the ADC internal temperature measures junction temperature. I expected +/- 5 C swing, not -14 C.
I can also confirm my ADC is working with DMA as I am using it to read internal voltage and various other analog measurements.
For this particular micocontroller, the values are taken off the datasheet and are designed to spec:
I am usingthelow level driver function to determine temperature:
/**
* @brief Helper macro to calculate the temperature (unit: degree Celsius)
* from ADC conversion data of internal temperature sensor.
* @note Computation is using temperature sensor typical values
* (refer to device datasheet).
* @note Calculation formula:
* Temperature = (TS_TYP_CALx_VOLT(uV) - TS_ADC_DATA * Conversion_uV)
* / Avg_Slope + CALx_TEMP
* with TS_ADC_DATA = temperature sensor raw data measured by ADC
* (unit: digital value)
* Avg_Slope = temperature sensor slope
* (unit: uV/Degree Celsius)
* TS_TYP_CALx_VOLT = temperature sensor digital value at
* temperature CALx_TEMP (unit: mV)
* Caution: Calculation relevancy under reserve the temperature sensor
* of the current device has characteristics in line with
* datasheet typical values.
* If temperature sensor calibration values are available on
* on this device (presence of macro __LL_ADC_CALC_TEMPERATURE()),
* temperature calculation will be more accurate using
* helper macro @ref __LL_ADC_CALC_TEMPERATURE().
* @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 ADC measurement data must correspond to a resolution of 12bits
* (full scale digital value 4095). If not the case, the data must be
* preliminarily rescaled to an equivalent resolution of 12 bits.
* @param __TEMPSENSOR_TYP_AVGSLOPE__ Device datasheet data: Temperature sensor slope typical value (unit: uV/DegCelsius).
* On STM32L0, refer to device datasheet parameter ''Avg_Slope''.
* @param __TEMPSENSOR_TYP_CALX_V__ Device datasheet data: Temperature sensor voltage typical value (at temperature and Vref+ defined in parameters below) (unit: mV).
* On STM32L0, refer to device datasheet parameter ''V130'' (corresponding to TS_CAL2).
* @param __TEMPSENSOR_CALX_TEMP__ Device datasheet data: Temperature at which temperature sensor voltage (see parameter above) is corresponding (unit: mV)
* @param __VREFANALOG_VOLTAGE__ Analog voltage reference (Vref+) 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)
*/
#define __LL_ADC_CALC_TEMPERATURE_TYP_PARAMS(__TEMPSENSOR_TYP_AVGSLOPE__,\
__TEMPSENSOR_TYP_CALX_V__,\
__TEMPSENSOR_CALX_TEMP__,\
__VREFANALOG_VOLTAGE__,\
__TEMPSENSOR_ADC_DATA__,\
__ADC_RESOLUTION__) \
((( ( \
(int32_t)((((__TEMPSENSOR_ADC_DATA__) * (__VREFANALOG_VOLTAGE__)) \
/ __LL_ADC_DIGITAL_SCALE(__ADC_RESOLUTION__)) \
* 1000) \
- \
(int32_t)(((__TEMPSENSOR_TYP_CALX_V__)) \
* 1000) \
) \
) / (__TEMPSENSOR_TYP_AVGSLOPE__) \
) + (__TEMPSENSOR_CALX_TEMP__) \
)
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// Values derived from datasheet STM32L011x4
#define ADC_TEMP_AVG_SLOPE 1610
#define ADC_TEMP_TYP_CALX_V 670
#define ADC_TEMP_TYP_CALX_TEMP 130
#define ADC_TEMP_REF_VOLTAGE 3300
int16_t adc_get_temperature_internal(void)
{
// Get Active Buffer (Opposite End of What the DMA is Filling)
// Covert Values Into a Voltage.
if(adc_active_buffer)
{
return __LL_ADC_CALC_TEMPERATURE_TYP_PARAMS(ADC_TEMP_AVG_SLOPE,
ADC_TEMP_TYP_CALX_V,
ADC_TEMP_TYP_CALX_TEMP,
ADC_TEMP_REF_VOLTAGE,
data[ADC_DMA_LOWER_TEMPERATURE_INTERNAL],
LL_ADC_RESOLUTION_12B);
}
else
{
return __LL_ADC_CALC_TEMPERATURE_TYP_PARAMS(ADC_TEMP_AVG_SLOPE,
ADC_TEMP_TYP_CALX_V,
ADC_TEMP_TYP_CALX_TEMP,
ADC_TEMP_REF_VOLTAGE,
data[ADC_DMA_UPPER_TEMPERATURE_INTERNAL],
LL_ADC_RESOLUTION_12B);
}
}
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