Differenze di lettura tra sketch

Ciao
Sto confrontando alcune board per sensori di temperatura
max 31855
max 6675
per termocoppia tipo K
max 31865
per una PT100

ho messo tutto in uno sketch ma il max 31855 da valori diversi da quelli che ottengo se lo uso singolarmente con l’esempio della libreria

/***************************************************
  This is an example for the Adafruit Thermocouple Sensor w/MAX31855K

  Designed specifically to work with the Adafruit Thermocouple Sensor
  ----> https://www.adafruit.com/products/269

  These displays use SPI to communicate, 3 pins are required to
  interface
  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.
  BSD license, all text above must be included in any redistribution
 ****************************************************/

#include <SPI.h>
#include "Adafruit_MAX31855.h"

// Default connection is using software SPI, but comment and uncomment one of
// the two examples below to switch between software SPI and hardware SPI:

// Example creating a thermocouple instance with software SPI on any three
// digital IO pins.
#define MAXDO   6
#define MAXCS   7
#define MAXCLK  8

// initialize the Thermocouple
Adafruit_MAX31855 thermocouple(MAXCLK, MAXCS, MAXDO);

// Example creating a thermocouple instance with hardware SPI
// on a given CS pin.
//#define MAXCS   10
//Adafruit_MAX31855 thermocouple(MAXCS);

// Example creating a thermocouple instance with hardware SPI
// on SPI1 using specified CS pin.
//#define MAXCS   10
//Adafruit_MAX31855 thermocouple(MAXCS, SPI1);

void setup() {
  Serial.begin(9600);

  while (!Serial) delay(1); // wait for Serial on Leonardo/Zero, etc

  Serial.println("MAX31855 test");
  // wait for MAX chip to stabilize
  delay(500);
  Serial.print("Initializing sensor...");
  if (!thermocouple.begin()) {
    Serial.println("ERROR.");
    while (1) delay(10);
  }
  Serial.println("DONE.");
}

void loop() {
  // basic readout test, just print the current temp
   Serial.print("Internal Temp = ");
   Serial.println(thermocouple.readInternal());

   double c = thermocouple.readCelsius();
   if (isnan(c)) {
     Serial.println("Something wrong with thermocouple!");
   } else {
     Serial.print("C = ");
     Serial.println(c);
   }
   //Serial.print("F = ");
   //Serial.println(thermocouple.readFahrenheit());

   delay(1000);
}

questo è l’output

MAX31855 test
Initializing sensor...DONE.
Internal Temp = 25.75
C = 27.75
Internal Temp = 26.87
C = 21.50
Internal Temp = 27.31
C = 22.25
Internal Temp = 27.69
C = 22.50

mentre se uso lo sketch che ho creato inglobando l’esempio della libreria


//2021 04 22
//#include <Adafruit_MAX31865.h> PT100
//in questo sketch vengono utilizzati insieme per verificare le differenze

//#include "max6675.h"  termocoppia tipo K
//sensori in parallelo per verificare corrispondenza

//#include "Adafruit_MAX31855.h" termocoppia

//#include "Adafruit_MCP9808.h"
//sensori in parallelo per verificare corrispondenza
/***************************************************
  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
  interface
  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.
  BSD license, all text above must be included in any redistribution


  // this example is public domain. enjoy!
  // https://learn.adafruit.com/thermocouple/
 ****************************************************/
/////////////////////////////////////////////////termocoppia con max 31855
#include <SPI.h>
#include "Adafruit_MAX31855.h"

// Default connection is using software SPI, but comment and uncomment one of
// the two examples below to switch between software SPI and hardware SPI:

// Example creating a thermocouple instance with software SPI on any three
// digital IO pins.
#define MAXDO   6
#define MAXCS   7
#define MAXCLK  8
//
// initialize the Thermocouple
Adafruit_MAX31855 thermocouple_1(MAXCLK, MAXCS, MAXDO);
//
//// Example creating a thermocouple instance with hardware SPI
//// on a given CS pin.
////#define MAXCS   10
////Adafruit_MAX31855 thermocouple_1(MAXCS);
//
//// Example creating a thermocouple instance with hardware SPI
//// on SPI1 using specified CS pin.
////#define MAXCS   10
////Adafruit_MAX31855 thermocouple_1(MAXCS, SPI1);

/////////////////////////////////////////////////termocoppia con max 6675
#include "max6675.h"
#define thermoDO  3
#define thermoCS  4
#define thermoCLK 5

MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);

//#define MAXDO   6
//#define MAXCS   7
//#define MAXCLK  8
////
//// initialize the Thermocouple
//MAX6675 thermocouple_1(MAXCLK, MAXCS, MAXDO);

//////////////////////////////////////////////////PT100 con max 31865
#include <Adafruit_MAX31865.h>
#define tCS 10
#define tSI 11
#define tSO 12
#define tCK 13
// Use software SPI: CS, DI, DO, CLK
Adafruit_MAX31865 thermo = Adafruit_MAX31865(tCS, tSI, tSO, tCK);
//Adafruit_MAX31865::Adafruit_MAX31865(int8_t spi_cs, int8_t spi_mosi, int8_t spi_miso, int8_t spi_clk) {

// use hardware SPI, just pass in the CS pin
//Adafruit_MAX31865 thermo = Adafruit_MAX31865(10);

// The value of the Rref resistor. Use 430.0 for PT100 and 4300.0 for PT1000
#define RREF      430.0
// The 'nominal' 0-degrees-C resistance of the sensor
// 100.0 for PT100, 1000.0 for PT1000
#define RNOMINAL  100.0

void setup()
{
  Serial.begin(9600);
  while (!Serial) delay(1); // wait for Serial on Leonardo/Zero, etc
  ////////////////////////////////////////////////////////////////////max 31855
  Serial.println("MAX31855 test");
  // wait for MAX chip to stabilize
  delay(500);
  Serial.print("Initializing sensor...");
  if (!thermocouple_1.begin())
  {
    Serial.println("ERROR.");
    while (1) delay(10);
  }
  Serial.println("DONE.");

  ////////////////////////////////////////////////////////////////PT100 con max 31865
  Serial.println("Adafruit MAX31865 PT100 Sensor Test!");
  thermo.begin(MAX31865_3WIRE);  // set to 2WIRE or 4WIRE as necessary
  delay(1000);
}

void loop()
{
  //////////////////////////////////////////////////termocoppia con max 31855
  // basic readout test, just print the current temp
  Serial.println("Max31855");
  //  Serial.print("Internal Temp = ");
  //  Serial.println(thermocouple_1.readInternal());

  double c = thermocouple_1.readCelsius();
  if (isnan(c))
  {
    Serial.println("Something wrong with thermocouple!");
  }
  else
  {
    Serial.print("Temperature = ");
    // Serial.print("C = ");
    Serial.println(c);
  }
  //Serial.print("F = ");
  //Serial.println(thermocouple_1.readFahrenheit());
  // digitalWrite(MAXCS, LOW);
  Serial.println();
  delay(1000);

  /////////////////////////////////////////////PT100 max 31865
  Serial.println("Max31865");
  uint16_t rtd = thermo.readRTD();

  //  Serial.print("RTD value: ");
  //  Serial.println(rtd);
  float ratio = rtd;
  ratio /= 32768;
  //  Serial.print("Ratio = ");
  //  Serial.println(ratio, 8);
  //  Serial.print("Resistance = ");
  //  Serial.println(RREF * ratio, 8);
 // Serial.println("PT100");
  Serial.print("Temperature = ");
  Serial.println(thermo.temperature(RNOMINAL, RREF));

  // Check and print any faults
  uint8_t fault = thermo.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");
    }
    thermo.clearFault();
  }
  Serial.println();
  delay(1000);

  ////////////////////////////////////////////termocoppia con max 6675
  // basic readout test, just print the current temp
  Serial.println("Max6675");
  Serial.print("Temperature = ");
  //Serial.print("C = ");
  Serial.println(thermocouple.readCelsius());
  //   Serial.print("F = ");
  //  Serial.println(thermocouple.readFahrenheit());

  // For the MAX6675 to update, you must delay AT LEAST 250ms between reads!
  Serial.println();
  delay(1000);

  //    // basic readout test, just print the current temp
  //  Serial.println("Max6675");
  //  Serial.print("Temperature = ");
  //  //Serial.print("C = ");
  //  Serial.println(thermocouple_1.readCelsius());
  //  //   Serial.print("F = ");
  //  //  Serial.println(thermocouple.readFahrenheit());
  //
  //  // For the MAX6675 to update, you must delay AT LEAST 250ms between reads!
  //  Serial.println();
  //  delay(1000);
}

ottengo questo output

MAX31855 test
Initializing sensor...DONE.
Adafruit MAX31865 PT100 Sensor Test!
Max31855
Temperature = 21.75

Max31865
Temperature = 20.43

Max6675
Temperature = 20.75

Max31855
Temperature = 14.50

Max31865
Temperature = 20.43

Max6675
Temperature = 21.00

Max31855
Temperature = 15.50

Max31865
Temperature = 20.46

Max6675
Temperature = 21.00

Max31855
Temperature = 15.75

Max31865
Temperature = 20.43

Max6675
Temperature = 20.50

Max31855
Temperature = 14.75

avete qualche idea
grazie

stefano