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Add getTemperature() to support internal temp sensor #159

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May 5, 2020
Merged

Add getTemperature() to support internal temp sensor #159

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Apr 29, 2020
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Add getTemperature() function. Update example 4 with new temp read fu…
Apr 29, 2020
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29 changes: 29 additions & 0 deletions cores/arduino/ard_sup/analog/ap3_analog.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -223,6 +223,35 @@ uint16_t analogRead(uint8_t pinNumber)
}
}

//Returns the internal temperature of the Apollo3
float getTemperature()
{
const float fReferenceVoltage = 2.0;
float fADCTempDegreesC = 0.0;

uint16_t internalTemp = analogRead(ADC_INTERNAL_TEMP); //Read internal temp sensor channel

//
// Convert and scale the temperature.
// Temperatures are in Fahrenheit range -40 to 225 degrees.
// Voltage range is 0.825V to 1.283V
// First get the ADC voltage corresponding to temperature.
//
float fADCTempVolts = ((float)internalTemp) * fReferenceVoltage / ((float)(pow(2, _analogBits)));

float fVT[3];
fVT[0] = fADCTempVolts;
fVT[1] = 0.0f;
fVT[2] = -123.456;
uint32_t ui32Retval = am_hal_adc_control(g_ADCHandle, AM_HAL_ADC_REQ_TEMP_CELSIUS_GET, fVT);
if (ui32Retval == AM_HAL_STATUS_SUCCESS)
{
fADCTempDegreesC = fVT[1]; // Get the temperature
}

return (fADCTempDegreesC);
}

//Power down ADC. Comes from adc_lpmode2.c example from Ambiq SDK
bool power_adc_disable()
{
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1 change: 1 addition & 0 deletions cores/arduino/ard_sup/ap3_analog.h
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Expand Up @@ -44,6 +44,7 @@ ap3_err_t ap3_change_channel(ap3_gpio_pad_t padNumber);
bool power_adc_disable();
uint16_t analogRead(uint8_t pinNumber);
ap3_err_t analogReadResolution(uint8_t bits);
float getTemperature();
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I feel like getTemperature() is just a bit too generic. What am I getting the temperature of? Should I be passing in an argument that is a value to convert to temperature?

How about something like getInternalTempC() or getChipTempC()?


ap3_err_t ap3_pwm_output(uint8_t pin, uint32_t th, uint32_t fw, uint32_t clk);
ap3_err_t analogWriteResolution(uint8_t res);
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5 changes: 1 addition & 4 deletions libraries/Examples/examples/Example4_analogRead/Example4_analogRead.ino
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Expand Up @@ -52,11 +52,8 @@ void loop()
Serial.print(vcc, 2);
Serial.print("V");

int internalTempVoltage = analogRead(ADC_INTERNAL_TEMP); //Read internal temp sensor. 3.8mV/C, +/-3C
double internalTemp = internalTempVoltage * vcc / 16384.0; //Convert internal temp reading to voltage
internalTemp /= 0.0038; //Convert voltage to degrees C
Serial.print("\tinternalTemp: ");
Serial.print(internalTemp, 2);
Serial.print(getTemperature(), 2);

int vss = analogRead(ADC_INTERNAL_VSS); //Read internal VSS (should be 0)
Serial.print("\tvss: ");
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