Issue in readings of internal Temperature Sensor

Posted on February 23, 2018 at 14:03

Hi Guys,

am using STM32f429, trying to read internal temperature sensor which is configured to ADC1  ADC_CHANNEL_18,

am able to read temperature readings,but  my device is giving 70 deg/C .

am not able to find why the  device is giving temperature that much high, following is the code which am using,

#define ADC_CHANNEL_DIFFERENCIATION_TEMPSENSOR_VBAT 0x10000000U

#define ADC_CHANNEL_TEMPSENSOR  ((uint32_t)ADC_CHANNEL_18 |ADC_CHANNEL_DIFFERENCIATION_TEMPSENSOR_VBAT)

#define ADC_CHANNEL_VREFINT ((uint32_t)ADC_CHANNEL_17)

#define ADC_CHANNEL_VBAT ((uint32_t)ADC_CHANNEL_18)

void TempINIT(void){

ADC_ChannelConfTypeDef sConfig;

AdcHandle.Instance = ADC1;

AdcHandle.Init.ClockPrescaler = ADC_CLOCKPRESCALER_PCLK_DIV2;

AdcHandle.Init.Resolution = ADC_RESOLUTION12b;

AdcHandle.Init.ScanConvMode = DISABLE; /* Sequencer disabled (ADC conversion on only 1 channel: channel set on rank 1) */

AdcHandle.Init.ContinuousConvMode = DISABLE; /* Continuous mode disabled to have only 1 conversion at each conversion trig */

AdcHandle.Init.DiscontinuousConvMode = DISABLE; /* Parameter discarded because sequencer is disabled */

//AdcHandle.Init.NbrOfDiscConversion = 0;

AdcHandle.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE; /* Conversion start trigged at each external event */

AdcHandle.Init.ExternalTrigConv = ADC_SOFTWARE_START;//ADC_EXTERNALTRIGCONV_T1_CC1;

AdcHandle.Init.DataAlign = ADC_DATAALIGN_RIGHT;

AdcHandle.Init.NbrOfConversion = 1;

AdcHandle.Init.DMAContinuousRequests = DISABLE;

AdcHandle.Init.EOCSelection = ADC_EOC_SINGLE_CONV;

if (HAL_ADC_Init(&AdcHandle) != HAL_OK)

{

/* ADC initialization Error */

Error_Handler();

}

/*##-2- Configure ADC regular channel ######################################*/

sConfig.Channel = ADC_CHANNEL_TEMPSENSOR ;

sConfig.Rank = 1;

sConfig.SamplingTime = ADC_SAMPLETIME_3CYCLES;

if (HAL_ADC_ConfigChannel(&AdcHandle, &sConfig) != HAL_OK)

{

/* Channel Configuration Error */

Error_Handler();

}

ADC->CCR &= ~ADC_CCR_VBATE;

}

uint8_t GetTempValue(float *TempValue_degC) {

unsigned short int count;

uint32_t Adc_Value =0;

uint32_t Adc_Value2 =0;

float vsense=0;

float samples =0;

float Temp;

TempINIT();

for(count=0;count<20;count++) {

HAL_ADC_Start(&AdcHandle);

if (HAL_ADC_PollForConversion(&AdcHandle, 1) == HAL_OK) {

Adc_Value = (uint16_t)HAL_ADC_GetValue(&AdcHandle);

Adc_Value2 =Adc_Value;

samples+=Adc_Value;

}

else {

Adc_Value = 0;

return ERROR;

}

HAL_ADC_Stop(&AdcHandle);

}

samples = samples/20;

vsense = ((samples)*(3300))/4096;

Temp = (((vsense) - (760))/(2.5)) + 25;

*TempValue_degC = Temp;

Adc_Value = 0;

samples = 0;

return SUCCESS;

}

/**

Thanks In Advance

with regards,

Himasagar.