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Lekcia 47: Použitie K-typu MAX6675 ako termostatu s relé | Kurz Arduino Krok za krokom

Lekcia 47: Použitie K-typu MAX6675 ako termostatu s relé | Kurz Arduino Krok za krokom

Tento projekt vás prevedie stavbou systému regulácie teploty pomocou Arduina, termočlánku K-type MAX6675 a relé. Tento systém dokáže udržiavať požadovaný rozsah teplôt, vďaka čomu je vhodný na rôzne aplikácie. Môžete ho použiť na stavbu:

  • Inkubátora s reguláciou teploty pre citlivé experimenty alebo priesady.
  • Automatizovaného varného systému na udržiavanie konzistentnej teploty mladiny.
  • Klimatizovaného priestoru pre plazy alebo iné teplocitlivé zvieratá.
  • Jednoduchého vykurovacieho alebo chladiaceho systému pre malý priestor.
  • robojax_course_47_MAX6675_temperature-0

Systém používa MAX6675 na čítanie teplôt z termočlánku K-type, čo poskytuje presné merania teploty v širokom rozsahu (v závislosti od typu termočlánku až do 1000°C alebo viac). Arduino spracúva tieto hodnoty a ovláda relé na zapínanie alebo vypínanie vykurovacieho alebo chladiaceho prvku, čím udržiava teplotu v rámci používateľom definovaného rozsahu. (vo videu o 00:32)

robojax_course_47_MAX6675_temperature-1
robojax_course_47_MAX6675_temperature-2-cool

Hardvér/Komponenty

Na stavbu tohto projektu budete potrebovať nasledujúce komponenty:

  • Doska Arduino (Uno, Nano atď.)
  • Zosilňovač termočlánku MAX6675
  • Termočlánok K-type
  • Reléový modul
  • AC žiarovka (alebo iná záťaž, napríklad ventilátor alebo ohrievač)
  • Prepojovacie vodiče
  • Nepájivé pole (voliteľné, ale odporúčané)

Sprievodca zapojením

Zapojenie je podrobne vysvetlené vo videu. (vo videu o 03:28) Pozrite si video pre vizuálny návod. Kľúčové pripojenia zahŕňajú pripojenie MAX6675 k Arduinu (piny 2-6), reléového modulu k Arduinu (pin 8 a napájanie) a reléového modulu k AC záťaži. Kritickým aspektom je správna identifikácia fázového a nulového vodiča vašej AC záťaže pred ich pripojením k relé. Nesprávne zapojenie môže viesť k nebezpečným situáciám.

robojax_course_47_MAX6675_relay_wiring

Vysvetlenie kódu

Kód Arduina (zobrazený v úryvkoch nižšie) využíva knižnicu MAX6675 na čítanie hodnôt teploty z termočlánku. Používateľsky konfigurovateľné časti kódu sú:

  • relayPin: Pin Arduina pripojený k reléovému modulu (predvolené: 8). (vo videu o 07:35)
  • relayON a relayOFF: Tieto konštanty definujú logické úrovne na zapnutie a vypnutie relé. Zvyčajne sú to LOW a HIGH, ale môže byť potrebné ich upraviť v závislosti od vášho reléového modulu. (vo videu o 07:35)
  • TEMPERATURE_UNIT: Nastavuje jednotku pre meranie teploty (1 pre Celzia, 2 pre Fahrenheita, 3 pre Kelvina). (vo videu o 08:21)
  • START_TEMPERATURE a STOP_TEMPERATURE: Tieto premenné definujú rozsah teplôt pre riadiaci systém. Systém zapne relé, keď teplota klesne pod START_TEMPERATURE, a vypne ho, keď teplota dosiahne STOP_TEMPERATURE (alebo naopak, v závislosti od toho, či ovládate ohrievač alebo chladič). (vo videu o 08:31)
  • CONTROL_TYPE: Premenná, ktorá určuje, či systém funguje ako ohrievač (1) alebo chladič (2). (vo videu o 08:36)

Kód obsahuje funkcie ako readTemperature(), printTemperature(), loadControl() a relayControl() na spracovanie čítania teploty, zobrazenia a činnosti relé. Tieto funkcie sú jasne definované a vysvetlené vo videu. (vo videu o 09:37, 10:00, 10:43, 11:30)


const int relayPin =8;
const int relayON = LOW;// do not change
const int relayOFF = HIGH; //do not change 
int relayState = relayOFF;//initial state of relay

const int TEMPERATURE_UNIT =1;//1=Celsius, 2=Fahrenheit, 3=Kelvin
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

Živý projekt/Demonštrácia

Video demonštruje fungovanie systému regulácie teploty pre scenáre vykurovania aj chladenia. (vo videu o 13:15 a 15:28) Demonštrácia jasne ukazuje, ako systém udržiava teplotu v nastavenom rozsahu zapínaním a vypínaním relé podľa potreby.

Kapitoly

  • [00:00] Úvod
  • [00:55] Vysvetlenie ovládania ohrievača/chladiča
  • [03:28] Schéma zapojenia
  • [06:26] Vysvetlenie kódu
  • [13:15] Demonštrácia ovládania ohrievača
  • [15:28] Demonštrácia ovládania chladiča
  • [17:29] Záver

Images

robojax_course_47_MAX6675_temperature-0
robojax_course_47_MAX6675_temperature-0
robojax_course_47_MAX6675_temperature-2-cool
robojax_course_47_MAX6675_temperature-2-cool
robojax_course_47_MAX6675_temperature-1
robojax_course_47_MAX6675_temperature-1
robojax_course_47_MAX6675_relay_wiring
robojax_course_47_MAX6675_relay_wiring
25-Arduino code for a MAX6675 K-type thermocouple with relay (no display)
Language: C++
/*
 * This is the Arduino code for MAX6675 Thermocouple K-Type with Relay and Display
 * The output pin 10 is connected to the relay.
 * When the temperature reaches the desired value, pin 10 turns the 
 * relay ON.

 * This code has been explained in our video at https://youtu.be/cD5oOu4N_AE

 * 
 * Written by Ahmad Nejrabi for Robojax Video
 * Date: December 9, 2017, in Ajax, Ontario, Canada
 * Permission granted to share this code given that this
 * note is kept with the code.
 * Disclaimer: This code is "AS IS" and for educational purposes only.
 * 
 */

 // This example is public domain. Enjoy!
// www.ladyada.net/learn/sensors/thermocouple

#include "max6675.h"


int thermoDO = 4;
int thermoCS = 5;
int thermoCLK = 6;


MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);
int vccPin = 3;
int gndPin = 2;
  
void setup() {
  Serial.begin(9600);
  // Use Arduino pins 
  pinMode(vccPin, OUTPUT); digitalWrite(vccPin, HIGH);
  pinMode(gndPin, OUTPUT); digitalWrite(gndPin, LOW);
    pinMode(10, OUTPUT);// set pin 10 as output
	
  Serial.println("Robojax: MAX6675 test");
  // wait for MAX chip to stabilize
  delay(500);
}

void loop() {
  // basic readout test, just print the current temp


   Serial.print("C = "); 
   Serial.println(thermocouple.readCelsius());
   Serial.print("F = ");
   Serial.println(thermocouple.readFahrenheit());

   // If temperature goes above 80.0C, turn the relay ON
   if(thermocouple.readCelsius() > 80.00){
    digitalWrite(10, LOW);// set pin 10 LOW
   }else{
    digitalWrite(10, HIGH);// set pin 10 HIGH
   }
    
 
   delay(1000);
}
757-Arduino code to measure a MAX6675 K-type thermocouple
Language: C++
++
/*
 * Library from: // www.ladyada.net/learn/sensors/thermocouple
 * 
 * This is Arduino code to measure MAX6675 Thermocouple K-Type sensor
 * and control relay as heater or cooler
 * 
 * Watch Video instruction for this code: https://youtu.be/dVh77wT-4Ao
 * 
 
 * Written by Ahmad Shamshiri on May 20, 2020 in Ajax, Ontario, Canada
 * www.robojax.com
 * 

 * Get this code and other Arduino codes from Robojax.com.
Learn Arduino step by step in a structured course with all material, wiring diagrams, and libraries
all in one place. Purchase My course on Udemy.com http://robojax.com/L/?id=62

If you found this tutorial helpful, please support me so I can continue creating 
content like this. 

or make a donation using PayPal http://robojax.com/L/?id=64
Related videos:
Introduction to MAX6675 K-Type: https://youtu.be/VGqONmUinqA
Using MAX6675 K-Type thermocouple with LED display: https://youtu.be/cD5oOu4N_AE
Using MAX6675 K-Type thermocouple with LCD1602-I2C: https://youtu.be/BlhpktgPdKs
Using 2 or more MAX6675 K-Type thermocouples: https://youtu.be/c90NszbNG8c
Using MAX6675 K-Type thermocouple as heater or cooler controller: [this video]
 *  * 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 downloaded 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 change 
int relayState = relayOFF;//initial state of relay

const int TEMPERATURE_UNIT =1;//1=Celsius, 2=Fahrenheit, 3=Kelvin
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
  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() {
  //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()
{
//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)
{
  //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  

}//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()
{
 //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 = Kelvin
 *     F = Fahrenheit
 * @return none
 * Written by Ahmad Shamshiri for robojax.com
 * on May 08, 2020 at 02:45 in Ajax, Ontario, Canada
 */
void printTemperature()
{
//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()
{
    Serial.print("\\xC2"); 
    Serial.print("\\xB0");  
}

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