fantemp/thermistor/main.cpp

#include "clock.hpp"

#include <math.h>
#include <stdint.h>
#include <stdio.h>

#include "flash/flash.hpp"
#include "io/io.hpp"
#include "uart/uart.hpp"

#define ADC_INT_VECTOR
#include "adc/adc.hpp"

#define UART0_INT_VECTORS
#include "uart/hardware0.hpp"

static constexpr auto SERIES_RESISTOR = 9951;
static constexpr auto THERMISTOR_NOMINAL = 9270;
static constexpr auto BETA_COEFFICIENT = 3212;
static constexpr auto NOMINAL_TEMPERATURE = 25;

template <typename Adc>
double sampleAdc(Adc &adcPin, uint16_t numSamples = 100)
{
	double samples = 0;

	for (uint16_t i = 0; i < numSamples; ++i)
		samples += adcPin.read();

	return samples / numSamples;
}

double getResistance(double adcSample)
{
	return SERIES_RESISTOR * adcSample / (1023 - adcSample);
}

double getTemperature(double resistance)
{
	double steinhart = resistance / THERMISTOR_NOMINAL;
	steinhart = log(steinhart);
	steinhart /= BETA_COEFFICIENT;
	steinhart += 1.0 / (NOMINAL_TEMPERATURE + 273.15);
	steinhart = 1.0 / steinhart;
	steinhart -= 273.15;
	return steinhart;
}

int main()
{
	uart::Uart0<> serial;
	serial.init();

	serial << F("Thermistor reader\r\n");

	using adc_conf = adc::Config<adc::SingleMode>;

	adc::Adc<adc_conf, io::P, io::P::C0> adcPin;
	adcPin.init();

	while (true) {
		const auto adcSample = sampleAdc(adcPin, 1000);
		const auto thermistorResistance = getResistance(adcSample);
		const auto temperature = getTemperature(thermistorResistance);

		char floatBuffer[16];

		sprintf(floatBuffer, "%.2f", adcSample);
		serial << F("Read ADC: ") << floatBuffer << F("\r\n");
		sprintf(floatBuffer, "%.2f", thermistorResistance);
		serial << F("Resistance: ") << floatBuffer << F("\r\n");
		sprintf(floatBuffer, "%.2f", temperature);
		serial << F("Temperature: ") << floatBuffer << F(" C \r\n");

		_delay_ms(1000);
	}

	serial.flushTx();

	return 0;
}