I uploaded my first version of the code. Now this is not PID control, have that in mind. Is just proportional control where I change the duty cycle, I count the elapsed time and measure the temperature and I try to get closer as I can to the curve shape of the sodler paste melting that found in the internet. Download the needed libraries from below as well for the LCD and the MAX6675 thermocopuple.
//Libraries
#include "max6675.h" //Download it here: http://electronoobs.com/eng_arduino_max6675.php
#include <Wire.h>
#include <LiquidCrystal_I2C.h> //Download it here: http://electronoobs.com/eng_arduino_liq_crystal.php
//Inputs Outputs
int SSR = 3;
int thermoDO = 4; //Data pin for MAX6675
int thermoCS = 5; //CS pin for MAX6675
int thermoCLK = 6; //Clock pin for MAX6675
int DT = 8; //Data pin for encoder
int CLK = 9; //Clock pin for encoder
int but_1 = 11; //Button 1 input
int but_2 = 10; //Button 2 input
int buzzer = 12; //Buzzer output pin
MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO); //Start MAX6675 SPI communication
LiquidCrystal_I2C lcd(0x27,20,4); //Address could be 0x3f or 0x27
//Variables
unsigned int millis_before, millis_before_2;
unsigned int millis_now = 0;
int refresh_rate = 1000;
int pid_refresh_rate = 300;
unsigned int seconds = 0;
int running_mode = 0;
int selected_mode = 0;
int max_modes = 1;
bool but_1_state = true;
bool but_2_state =true;
float pwm_value = 5;
int max_pwm_value = 40;
int min_pwm_value = 2;
float temp_setpoint = 0;
float temperature = 0;
void setup() {
//Define the OUTPUTs
pinMode(SSR, OUTPUT); //Start with the SSR off
digitalWrite(SSR, LOW);
pinMode(buzzer, OUTPUT); //Start with buzzer off
digitalWrite(buzzer, LOW);
//Define the INPUTS
pinMode(DT, INPUT_PULLUP);
pinMode(CLK, INPUT_PULLUP);
pinMode(but_1, INPUT_PULLUP);
pinMode(but_2, INPUT_PULLUP);
Serial.begin(9600);
lcd.init(); //Init the LCD
lcd.backlight(); //Activate backlight
millis_before = millis();
millis_now = millis();
}
void loop() {
millis_now = millis();
if(millis_now - millis_before_2 > pid_refresh_rate){
millis_before_2 = millis();
temperature = thermocouple.readCelsius();
if(running_mode == 1){
if(temperature < 150){
temp_setpoint = seconds;
if(temp_setpoint > temperature){
pwm_value = pwm_value + 0.3;
if(pwm_value > max_pwm_value){
pwm_value = max_pwm_value;
}
}
else{
pwm_value--;
if(pwm_value < min_pwm_value){
pwm_value = min_pwm_value;
}
}
}
else if(temperature > 140){
max_pwm_value = 60;
temp_setpoint = 200;
if(temp_setpoint > temperature){
pwm_value = pwm_value + 0.3;
if(pwm_value > max_pwm_value){
pwm_value = max_pwm_value;
}
}
else{
pwm_value--;
if(pwm_value < min_pwm_value){
pwm_value = min_pwm_value;
}
}
}
analogWrite(SSR, pwm_value); //We change the Duty Cycle
if(temperature > 190){
running_mode = 10;
analogWrite(SSR, LOW);
}
}//end of running_mode == 1
if(running_mode == 10){
lcd.clear();
lcd.setCursor(0,1);
lcd.print(" COMPLETE ");
tone(buzzer, 1000, 1000);
seconds = 0; //Reset timer
running_mode = 11;
delay(2000);
}
}//end of pid_refresh_rate
if(millis_now - millis_before > refresh_rate){
millis_before = millis();
seconds = seconds + (refresh_rate/1000); //We count time
Serial.println(temperature);
if(running_mode == 0){
digitalWrite(SSR, LOW);
lcd.clear();
lcd.setCursor(0,0);
lcd.print("Temp: ");
lcd.print(temperature,1);
lcd.setCursor(0,1);
lcd.print("SSR: OFF");
lcd.setCursor(0,2);
lcd.print("SELECTED MODE: ");
lcd.print(selected_mode);
lcd.setCursor(0,3);
lcd.print("NOT RUNNING");
}//end of running_mode == 0
else if(running_mode == 11){
if(temperature < 40){
running_mode = 0;
tone(buzzer, 1000, 100);
}
digitalWrite(SSR, LOW);
lcd.clear();
lcd.setCursor(0,0);
lcd.print("Temp: ");
lcd.print(temperature,1);
lcd.setCursor(0,1);
lcd.print("SSR: OFF");
lcd.setCursor(0,2);
lcd.print("SELECTED MODE: ");
lcd.print(selected_mode);
lcd.setCursor(0,3);
lcd.print("COOLDOWN");
}//end of running_mode == 0
else if(running_mode == 1){
lcd.clear();
lcd.setCursor(0,0);
lcd.print("Temp: ");
lcd.print(temperature,1);
lcd.setCursor(0,1);
lcd.print("SSR: ON "); lcd.print("Time: "); lcd.print(seconds);
lcd.setCursor(0,2);
lcd.print("SELECTED MODE: ");
lcd.print(selected_mode);
lcd.setCursor(0,3);
lcd.print("RUNNING | PWM: "); lcd.print(pwm_value,1);
}//end of running_mode == 1
}//end of millis_now - millis_before > refresh_rate
///////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////
if(!digitalRead(but_1) && but_1_state){
but_1_state = false;
selected_mode ++;
millis_before = millis_before-1000;
if(selected_mode > max_modes){
selected_mode = 0;
}
}
else if(digitalRead(but_1) && !but_1_state){
but_1_state = true;
}
///////////////////////////////////////////////////////////////////
if(!digitalRead(but_2) && but_2_state){
if(running_mode == 1){
digitalWrite(SSR, LOW);
running_mode = 0;
selected_mode = 0;
}
but_2_state = false;
if(selected_mode == 0){
running_mode = 0;
}
else if(selected_mode == 1){
running_mode = 1;
tone(buzzer, 1000, 1000);
seconds = 0; //Reset timer
}
}
else if(digitalRead(but_2) && !but_2_state){
but_2_state = true;
}
///////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////
}//end of void loop
