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Update pt100_temperature.ino #8

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172 changes: 84 additions & 88 deletions examples/pt100_temperature/pt100_temperature.ino
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Original file line number Diff line number Diff line change
@@ -1,25 +1,21 @@


#include <Wire.h>

#include <SPI.h>

/***************************************************
/***************************************************
This is a library for the Adafruit PT100/P1000 RTD Sensor w/MAX31865

Designed specifically to work with the Adafruit RTD Sensor
----> https://www.adafruit.com/products/3328

This sensor uses SPI to communicate, 4 pins are required to
This sensor uses SPI to communicate, 4 pins are required to
interface
Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing
Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing
products from Adafruit!

Written by Limor Fried/Ladyada for Adafruit Industries.
Written by Limor Fried/Ladyada for Adafruit Industries.
BSD license, all text above must be included in any redistribution
****************************************************/

#include <Wire.h>
#include <SPI.h>
#include <Adafruit_MAX31865.h>
#include <pt100rtd.h>

Expand All @@ -40,92 +36,92 @@ pt100rtd PT100 = pt100rtd() ;

void setup()
{
Serial.begin(57600) ;
Serial.println("MAX31865 PT100 Sensor Test using NIST resistance table.");
Serial.begin(115200) ;
Serial.println("MAX31865 PT100 Sensor Test using NIST resistance table.");

//max.begin(MAX31865_2WIRE); // set to 2WIRE or 4WIRE as necessary
//max.begin(MAX31865_3WIRE); // set to 2WIRE or 4WIRE as necessary
max.begin(MAX31865_4WIRE); // set to 2WIRE or 4WIRE as necessary
//max.begin(MAX31865_2WIRE); // set to 2WIRE or 4WIRE as necessary
//max.begin(MAX31865_3WIRE); // set to 2WIRE or 4WIRE as necessary
max.begin(MAX31865_4WIRE); // set to 2WIRE or 4WIRE as necessary
}

void checkFault(void)
{
// Check and print any faults
uint8_t fault = max.readFault();
if (fault)
{
Serial.print("Fault 0x"); Serial.println(fault, HEX);
if (fault & MAX31865_FAULT_HIGHTHRESH)
{
Serial.println("RTD High Threshold");
}
if (fault & MAX31865_FAULT_LOWTHRESH)
{
Serial.println("RTD Low Threshold");
}
if (fault & MAX31865_FAULT_REFINLOW)
{
Serial.println("REFIN- > 0.85 x Bias");
}
if (fault & MAX31865_FAULT_REFINHIGH)
{
Serial.println("REFIN- < 0.85 x Bias - FORCE- open");
}
if (fault & MAX31865_FAULT_RTDINLOW)
{
Serial.println("RTDIN- < 0.85 x Bias - FORCE- open");
}
if (fault & MAX31865_FAULT_OVUV)
{
Serial.println("Under/Over voltage");
}
max.clearFault();
}
// Check and print any faults
uint8_t fault = max.readFault();
if (fault)
{
Serial.print("Fault 0x"); Serial.println(fault, HEX);
if (fault & MAX31865_FAULT_HIGHTHRESH)
{
Serial.println("RTD High Threshold");
}
if (fault & MAX31865_FAULT_LOWTHRESH)
{
Serial.println("RTD Low Threshold");
}
if (fault & MAX31865_FAULT_REFINLOW)
{
Serial.println("REFIN- > 0.85 x Bias");
}
if (fault & MAX31865_FAULT_REFINHIGH)
{
Serial.println("REFIN- < 0.85 x Bias - FORCE- open");
}
if (fault & MAX31865_FAULT_RTDINLOW)
{
Serial.println("RTDIN- < 0.85 x Bias - FORCE- open");
}
if (fault & MAX31865_FAULT_OVUV)
{
Serial.println("Under/Over voltage");
}
max.clearFault();
}
}

void loop()
{
uint16_t rtd, ohmsx100 ;
uint32_t dummy ;
float ohms, Tlut ;
float Tcvd, Tcube, Tpoly, Trpoly ;

rtd = max.readRTD();

// fast integer math:
// fits in 32 bits as long as (100 * RREF) <= 2^16,
// i.e., RREF must not exceed 655.35 ohms (heh).
// TO DO: revise for 4000 ohm reference resistor needed by Pt1000 RTDs
// Use uint16_t (ohms * 100) since it matches data type in lookup table.
dummy = ((uint32_t)(rtd << 1)) * 100 * ((uint32_t) floor(RREF)) ;
dummy >>= 16 ;
ohmsx100 = (uint16_t) (dummy & 0xFFFF) ;

// or use exact ohms floating point value.
ohms = (float)(ohmsx100 / 100) + ((float)(ohmsx100 % 100) / 100.0) ;

Serial.print("rtd: 0x") ; Serial.print(rtd,HEX) ;
Serial.print(", ohms: ") ; Serial.println(ohms,2) ;
uint16_t rtd, ohmsx100 ;
uint32_t dummy ;
float ohms, Tlut ;
float Tcvd, Tcube, Tpoly, Trpoly ;

rtd = max.readRTD();

// fast integer math:
// fits in 32 bits as long as (100 * RREF) <= 2^16,
// i.e., RREF must not exceed 655.35 ohms (heh).
// TO DO: revise for 4000 ohm reference resistor needed by Pt1000 RTDs

// Use uint16_t (ohms * 100) since it matches data type in lookup table.
dummy = ((uint32_t)(rtd << 1)) * 100 * ((uint32_t) floor(RREF)) ;
dummy >>= 16 ;
ohmsx100 = (uint16_t) (dummy & 0xFFFF) ;

// or use exact ohms floating point value.
ohms = (float)(ohmsx100 / 100) + ((float)(ohmsx100 % 100) / 100.0) ;

Serial.print("rtd: 0x") ; Serial.print(rtd, HEX) ;
Serial.print(", ohms: ") ; Serial.println(ohms, 2) ;

// compare lookup table and common computational methods
Tlut = PT100.celsius(ohmsx100) ; // NoobNote: LUT== LookUp Table
Tcvd = PT100.celsius_cvd(ohms) ; // Callendar-Van Dusen calc
Tcube = PT100.celsius_cubic(ohms) ; // Cubic eqn calc
Tpoly = PT100.celsius_polynomial(ohms) ; // 5th order polynomial
Trpoly = PT100.celsius_rationalpolynomial(ohms) ; // ugly rational polynomial quotient
// report temperatures at 0.001C resolution to highlight methodological differences
Serial.print("Tlut = ") ; Serial.print(Tlut ,3) ; Serial.println(" C (exact)") ;
Serial.print("Tcvd = ") ; Serial.print(Tcvd ,3) ; Serial.println(" C") ;
Serial.print("Tcube = ") ; Serial.print(Tcube ,3) ; Serial.println(" C") ;
Serial.print("Tpoly = ") ; Serial.print(Tpoly ,3) ; Serial.println(" C") ;
Serial.print("Trpoly = ") ; Serial.print(Trpoly,3) ; Serial.println(" C") ;
Serial.println();
checkFault() ;

delay(5000) ;

Tlut = PT100.celsius(ohmsx100) ; // NoobNote: LUT== LookUp Table
Tcvd = PT100.celsius_cvd(ohms) ; // Callendar-Van Dusen calc
Tcube = PT100.celsius_cubic(ohms) ; // Cubic eqn calc
Tpoly = PT100.celsius_polynomial(ohms) ; // 5th order polynomial
Trpoly = PT100.celsius_rationalpolynomial(ohms) ; // ugly rational polynomial quotient

// report temperatures at 0.001C resolution to highlight methodological differences
Serial.print("Tlut = ") ; Serial.print(Tlut , 3) ; Serial.println(" C (exact)") ;
Serial.print("Tcvd = ") ; Serial.print(Tcvd , 3) ; Serial.println(" C") ;
Serial.print("Tcube = ") ; Serial.print(Tcube , 3) ; Serial.println(" C") ;
Serial.print("Tpoly = ") ; Serial.print(Tpoly , 3) ; Serial.println(" C") ;
Serial.print("Trpoly = ") ; Serial.print(Trpoly, 3) ; Serial.println(" C") ;
Serial.println();

checkFault() ;

delay(5000) ;

}