/*****************************************************************************
* Function Name: ProcessTemperature()
******************************************************************************
* Summary:
* Measures the current temperature.
*
* Parameters:
* None
*
* Return:
* uint32 - Measured temperature
*
* Theory:
* This function measures the reference voltage, thermistor voltage and
* offset voltage.
* Channel 0 - Reference voltage
* Channel 1 - Thermistor voltage
* Channel 2 - Offset voltage
*
* This function removes offset via correlated double sampling and then
* measures the temperature.
*
* Side Effects:
* None
*
* Note:
*
*****************************************************************************/
int32 ProcessTemperature (void)
{
/* Local variables used for temperature measurement */
static int32 temperature = 0;
#if (SIMULATE_TEMPERATURE_SENSOR)
int32 thermistorResistance = 0;
int16 referenceVoltage = 0;
int16 thermistorVoltage = 0;
int16 offsetVoltage = 0;
/* Check if measurement interval has expired */
if(SystemFlag & MEASUREMENT_INTERVAL)
{
/* Disconnect all the pins from Amux input */
AMuxSeq_DisconnectAll();
/* Measure reference voltage - Channel 0 */
referenceVoltage = MeasureSensorVoltage();
/* Measure thermistor voltage - Channel 0 */
thermistorVoltage = MeasureSensorVoltage();
/* Measure offset voltage - Channel 0 */
offsetVoltage = MeasureSensorVoltage();
/* Measure thermistor resistance and remove offset by using correlated
* double sampling. */
thermistorResistance = Thermistor_GetResistance((referenceVoltage - offsetVoltage), (thermistorVoltage - offsetVoltage));
/* Compute temperature and remove decimal places */
temperature = Thermistor_GetTemperature(thermistorResistance);
temperature = temperature / 100;
}
#else
/* Check if measurement interval has expired */
if (SystemFlag & MEASUREMENT_INTERVAL)
{
temperature++;
if(temperature > 100)
{
temperature = 0;
}
}
#endif
/* Return measured temperature */
return (temperature);
}
/*******************************************************************************
* Function Name: void processADC( void )
********************************************************************************
*
* Summary:
* This function calculates all values from the ADC each time a scan completes.
* The variable adcState is set to PROCESS by the ADC ISR each time a scan finishes.
* Once processing is done, the adcState variable is set to DONE so that the
* next scan can start.
*
* The values calculated are: Ambient light, temperature, and POT voltage.
*******************************************************************************/
void processADC(void)
{
int16 alsCurrent; /* Variable to store ALS current */
int16 illum16; /* Illuminance as a 16 bit value (lux) */
int16 thermistorResistance; /* Variables for temperature calculation */
int16 temp16; /* Temperature expressed as a 16 bit integer in 1/100th of a degree */
/* Process ADC results that were captured in the interrupt */
if(adcState == PROCESS)
{
/* ALS */
/* Calculate the photodiode current */
alsCurrent = (adcResults[ALS] * ALS_CURRENT_SCALE_FACTOR_NUMERATOR)/ALS_CURRENT_SCALE_FACTOR_DENOMINATOR;
/* If the calculated current is negative, limit it to zero */
if(alsCurrent < 0)
{
alsCurrent = 0;
}
/* Calculate the light illuminance */
illum16 = (alsCurrent * ALS_LIGHT_SCALE_FACTOR_NUMERATOR)/ALS_LIGHT_SCALE_FACTOR_DENOMINATOR;
LocData.illuminance = (float32)(illum16);
/* Thermistor */
/* Calculate thermistor resistance */
thermistorResistance = Thermistor_GetResistance(adcResults[THERM_REF], adcResults[THERM]);
/* Calculate temperature in degree Celsius using the Component API */
temp16 = Thermistor_GetTemperature(thermistorResistance);
/* Convert tempearture to a float */
LocData.temperature = ((float32)(temp16))/100.0;
/* POT */
LocData.potVal = ADC_CountsTo_Volts(POT, adcResults[POT]);
adcState = DONE;
}
}
