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In this lesson we learn how to use MAX6675 with relay as thermostat to keep temperature stead for industrial application. For echmical, melting or other applications. We can set range of temperature and Arduino will keep it at that level by controlling heater or cooler. Please watch the video for full details.
/*
* Robojax Arduino Step By Step Course
* Part 4: Temperature Sensors
* Lesson 47: Using Max6675 as Thermostat with relay
*
* This is Arduino code to measure MAX6675 Thermocoupler K-Type sensor
* and control realy as Heater or cooler
Please watch video instruction here https://youtu.be/yJYXfaU9J34
Introduction to MAX6675 video is https://youtu.be/A55QNx6kCoo
This code is available at http://robojax.com/course1/?vid=lecture47
Course worth of $200 with over 150 lectures Free On YouTube Watch it here http://robojax.com/L/?id=338
Get the code for the course: http://robojax.com/L/?id=339
* Written by Ahmad Shamshiri on May 20, 2020 at in Ajax, Ontario, Canada
* in Ajax, Ontario, Canada. www.robojax.com
*
* Library from : // www.ladyada.net/learn/sensors/thermocouple
*
or make donation using PayPal http://robojax.com/L/?id=64
* * This code is "AS IS" without warranty or liability. Free to be used as long as you keep this note intact.*
* This code has been download from Robojax.com
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "max6675.h"
//Robojax.com heater/cooler with MAX6675 Thermocoupler
int GNDpin = 2;
int VCCpin =3;
int thermoCLK = 4;
int thermoCS = 5;
int thermoDO = 6;
MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);
const int relayPin =8;
const int relayON = LOW;// do not change
const int relayOFF = HIGH; //do not chage
int relayState = relayOFF;//initial state of relay
const int TEMPERATURE_UNIT =1;//1=Celsius, 2=Fahrenheit, 3=Keliven
const float START_TEMPERATURE = 80.0;//unit above
const float STOP_TEMPERATURE = 100.0;//unit above
const int CONTROL_TYPE = 1;// 1= heater, 2=cooler
float temperature;
void setup() {
//Robojax.com heater/cooler with MAX6675 Thermocoupler
//free course YouTube Watch it here http://robojax.com/L/?id=338
Serial.begin(9600);
Serial.println("MAX6675 test with relay");
// use Arduino pins
pinMode(relayPin, OUTPUT);//pin for relay
digitalWrite(relayPin, relayState);
pinMode(VCCpin, OUTPUT);
digitalWrite(VCCpin, HIGH);
pinMode(GNDpin, OUTPUT);
digitalWrite(GNDpin, LOW);
// wait for MAX chip to stabilize
delay(500);
//Robojax.com heater/cooler with MAX6675 Thermocoupler
}
void loop() {
//free course YouTube Watch it here http://robojax.com/L/?id=338
//Robojax.com heater/cooler with MAX6675 Thermocoupler
readTemperature();
printTemperature();
loadControl();
if(temperature >=89.5)
{
///
}
delay(1000);
//Robojax.com heater/cooler with MAX6675 Thermocoupler
}//loop
/*
* loadControl()
* @brief controls the load based
* @param state can be either : relayON or relayOFF
* @return returns none
* Written by Ahmad Shamshiri for robojax.com
* on May 20, 2020 at 15:23 in Ajax, Ontario, Canada
*/
void loadControl()
{
//free course YouTube Watch it here http://robojax.com/L/?id=338
//Robojax.com heater/cooler with MAX6675 Thermocoupler
// Serial.print("Start: ");
// Serial.print(START_TEMPERATURE);
// Serial.print(" Stop: ");
//Serial.println(STOP_TEMPERATURE);
if(CONTROL_TYPE ==1)
{
if(START_TEMPERATURE >= temperature && STOP_TEMPERATURE >=temperature)
{
relayControl(relayON);
}
if(STOP_TEMPERATURE <=temperature)
{
relayControl(relayOFF);
}
}else{
if(START_TEMPERATURE >= temperature && STOP_TEMPERATURE >=temperature)
{
relayControl(relayOFF);
}
if(STOP_TEMPERATURE <=temperature)
{
relayControl(relayON);
}
}
//Robojax.com heater/cooler with MAX6675 Thermocoupler
}//loadControl()
/*
* relayControl(int state))
* @brief turns the relay ON or OFF
* @param state is "relayON" or "relayOFF" defined at the top of code
* @return returns none
* Written by Ahmad Shamshiri for robojax.com
* on May 20, 2020 at 15:23 in Ajax, Ontario, Canada
*/
void relayControl(int state)
{
//free course YouTube Watch it here http://robojax.com/L/?id=338
//Robojax.com heater/cooler with MAX6675 Thermocoupler
if(state ==relayON)
{
digitalWrite(relayPin, relayON);
Serial.println("Relay ON");
}else{
digitalWrite(relayPin, relayOFF);
Serial.println("Relay OFF");
}
//Robojax.com heater/cooler with MAX6675 Thermocoupler
//free course YouTube Watch it here http://robojax.com/L/?id=338
}//relayControl()
/*
* readTemperature()
* @brief reads the temperature based on the TEMPERATURE_UNIT
* @param average temperature
* @return returns one of the values above
* Written by Ahmad Shamshiri for robojax.com
* on May 20, 2020 at 15:23 in Ajax, Ontario, Canada
*/
void readTemperature()
{
//free course YouTube Watch it here http://robojax.com/L/?id=338
//Robojax.com heater/cooler with MAX6675 Thermocoupler
if(TEMPERATURE_UNIT ==2)
{
temperature = thermocouple.readFahrenheit();//convert to Fahrenheit
}else if(TEMPERATURE_UNIT ==3)
{
temperature = thermocouple.readCelsius() + 273.15;//convert to Kelvin
}else{
temperature = thermocouple.readCelsius();// return Celsius
}
//Robojax.com heater/cooler with MAX6675 Thermocoupler
}// readTemperature()
/*
* printTemperature()
* @brief prints temperature on serial monitor
* @param charact type
* @param "type" is character
* C = Celsius
* K = Keliven
* F = Fahrenheit
* @return none
* Written by Ahmad Shamshiri for robojax.com
* on May 08, 2020 at 02:45 in Ajax, Ontario, Canada
*/
void printTemperature()
{
//free course YouTube Watch it here http://robojax.com/L/?id=338
//Robojax.com heater/cooler with MAX6675 Thermocoupler
Serial.print(temperature);
printDegree();
if(TEMPERATURE_UNIT ==2)
{
Serial.print("F");
}else if(TEMPERATURE_UNIT ==3)
{
Serial.print("K");
}else{
Serial.print("C");
}
Serial.println();
//Robojax.com heater/cooler with MAX6675 Thermocoupler
}//printTemperature()
/*
* @brief prints degree symbol on serial monitor
* @param none
* @return returns nothing
* Written by Ahmad Shamshiri on July 13, 2019
* for Robojax Tutorial Robojax.com
*/
void printDegree()
{
//free course YouTube Watch it here http://robojax.com/L/?id=338
Serial.print("\xC2");
Serial.print("\xB0");
}
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