st-anything/lib/ST_Anything/PS_10kThermistor.cpp

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2023-03-11 14:11:03 +00:00
//******************************************************************************************
// File: PS_10kThermistor.cpp
// Authors: D. Johnson (_M2) based on the work of Dan G Ogorchock & Daniel J Ogorchock (Father and Son)
//
// Summary: PS_10kThermistor is a class which implements the Hubitat "Temperature Measurement" device capability.
// It inherits from the st::PollingSensor class. The current version uses an analog input to measure the
// value of a simple thermal resistor using another 10k resistor as a voltage divider.
//
// The last four arguments of the constructor are used as arguments to configure the resistance of the parts.
// The first number is the resistance of the thermistor. Second is R1. Third is the thermistor coefficient. Last is your preference of units.
// Create an instance of this class in your sketch's global variable section
// For Example: st::PS_10kThermistor sensor1(F("temperature1"), 120, 0, PIN_THERMISTOR, 10000, 10000, 3300, "F");
//
// st::PS_10kThermistor() constructor requires the following arguments
// - String &name - REQUIRED - the name of the object - must match the Groovy ST_Anything DeviceType tile name
// - long interval - REQUIRED - the polling interval in seconds
// - long offset - REQUIRED - the polling interval offset in seconds - used to prevent all polling sensors from executing at the same time
// - byte pin - REQUIRED - the Arduino Pin to be used as a digital output
// - int tl - OPTIONAL - resistance of the thermocouple at the nominal temperature (usually 25C, 77F)
// - int r1 - OPTIONAL - actual measured resistance of the voltage divider resistor
// - int BCOEFF - OPTIONAL - The beta coefficient of the thermistor (usually 3000-4000). Tweak this number to calibrate.
// - int tempNOM - OPTIONAL - The nominal temperature of the thermistor @10k (usually 25C, 77F).
// - int unit - OPTIONAL - Use the letter F for Farhenheit, C for Celsius
//
//
// TODO: Determine a method to persist the ST Cloud's Polling Interval data
//
// Change History:
//
// Date Who What
// ---- --- ----
// 2015-01-03 Dan & Daniel Original Creation
// 2017-08-30 Dan Ogorchock Modified comment section above to comply with new Parent/Child Device Handler requirements
// 2019-12-23 D. Johnson Created 10k_Thermistor using PS_Illuminance as example
//
//******************************************************************************************
#include "PS_10kThermistor.h"
#include "Constants.h"
#include "Everything.h"
namespace st
{
//private
//public
//constructor - called in your sketch's global variable declaration section
PS_10kThermistor::PS_10kThermistor(const __FlashStringHelper *name, unsigned int interval, int offset, byte analogInputPin, int t1, int r1, int BCOEFF, int tempNom, char unit):
PollingSensor(name, interval, offset),
m_nSensorValue(0),
thermResistance(t1),
r1Resistance(r1),
BetaCoeff(BCOEFF),
UNIT(unit),
TEMPNOMINAL(tempNom)
{
setPin(analogInputPin);
}
//destructor
PS_10kThermistor::~PS_10kThermistor()
{
}
//SmartThings Shield data handler (receives configuration data from ST - polling interval, and adjusts on the fly)
void PS_10kThermistor::beSmart(const String &str)
{
String s = str.substring(str.indexOf(' ') + 1);
if (s.toInt() != 0) {
st::PollingSensor::setInterval(s.toInt() * 1000);
if (st::PollingSensor::debug) {
Serial.print(F("PS_10kThermistor::beSmart set polling interval to "));
Serial.println(s.toInt());
}
}
else {
if (st::PollingSensor::debug)
{
Serial.print(F("PS_10kThermistor::beSmart cannot convert "));
Serial.print(s);
Serial.println(F(" to an Integer."));
}
}
}
//function to get data from sensor and queue results for transfer to ST Cloud
void PS_10kThermistor::getData()
{
int NUMSAMPLES = 10;
float samples[NUMSAMPLES];
for (int i=0; i< NUMSAMPLES; i++)
{
samples[i] = analogRead(m_nAnalogInputPin);
}
// average all the samples out
float average = 0;
for (int i=0; i< NUMSAMPLES; i++)
{
average += samples[i];
}
average /= NUMSAMPLES;
// convert the value to resistance
average = 1023 / average - 1;
average = r1Resistance / average;
float reading;
float Temp1F;
float Temp1C;
reading = average / thermResistance; // (R/Ro)
reading = log(reading); // ln(R/Ro)
reading /= BetaCoeff; // 1/B * ln(R/Ro)
reading += 1.0 / (TEMPNOMINAL + 273.15); // + (1/To)
reading = 1.0 / reading; // Invert
Temp1C = reading -= 273.15; // convert to C
Temp1F = (Temp1C * 1.8) + 32; // convert to F
if(UNIT == 'F'){
m_nSensorValue = Temp1F;
}
else {
m_nSensorValue = Temp1C;
}
Everything::sendSmartString(getName() + " " + String(m_nSensorValue));
}
void PS_10kThermistor::setPin(byte pin)
{
m_nAnalogInputPin = pin;
}
}