#include <max6675.h>

#include <ModbusRtu.h>

#include <SoftwareSerial.h>

SoftwareSerial mySerial(7, 8); // RX, TX



// data array for modbus network sharing

uint16_t au16data[16] = {

  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1

};



/**

    Modbus object declaration

    u8id : node id = 0 for master, = 1..247 for slave

    u8serno : serial port (use 0 for Serial)

    u8txenpin : 0 for RS-232 and USB-FTDI

                 or any pin number > 1 for RS-485

*/

Modbus slave(1, mySerial, 0); // this is slave @1 and RS-232 or USB-FTDI



// Pins for thermocouple MAX6675

int thermoDO = 6;

int thermoCS = 5;

int thermoCLK = 4;



MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);



// declare variable for Arduino pin connected to solid state relay (SSR)

int relay = 9;



// declare variables for Arduino pins connected to fan controller (L293N)

int fan = 10; // ENA of L239N

int in1 = 11; // IN1 of L239N

int in2 = 12; // IN1 of L239N



// declare variables for Arduino pins to power MAX6675:

int vccPin = 3; // 5v power of MAX6675

int gndPin = 2; // gnd of MAX6675



// slew rate limitations for fan control

#define SLEW_STEP 10 // increase in steps of 10% for smooth transition

int target = 0;

int current = 0;



void slew_fan() { // limit fan speed increases

  target = ((au16data[5] / 100.0) * 255);

  if ( target < current ) { // ramping down, so check rate

    uint8_t delta = current - target;

    if ( delta > SLEW_STEP ) // limit the step size

      delta = SLEW_STEP;

    analogWrite(fan, (current - delta ));

    current = current - delta;

  }

  else if ( target > current ) { // ramping up, so check rate

    uint8_t delta = target - current;

    if ( delta > SLEW_STEP ) // limit the step size

      delta = SLEW_STEP;

    //write current fan value for air control

    analogWrite(fan, (current + delta ));

    current = current + delta;

  }

}





void setup() {

  mySerial.begin(19200); // Soft Serial used for communication through Bluetooth module HC-06

  slave.start( ); // 19200 baud, 8-bits, even, 1-bit stop

  // use Arduino pins

  pinMode(relay, OUTPUT);

  pinMode(fan, OUTPUT);

  //fan direction can be reversed by interchanging values for in1 and in2

  pinMode(in1, OUTPUT); digitalWrite(in1, HIGH);

  pinMode(in2, OUTPUT); digitalWrite(in2, LOW);



  pinMode(vccPin, OUTPUT); digitalWrite(vccPin, HIGH);

  pinMode(gndPin, OUTPUT); digitalWrite(gndPin, LOW);

  delay(500);

}



void loop() {

  //write current thermocouple value

  au16data[2] = ((uint16_t) thermocouple.readCelsius() * 100);



  //write current fan value for air control

  // analogWrite(fan, (au16data[5] / 100.0) * 255);

  slew_fan();



  //poll modbus registers

  slave.poll( au16data, 16 );



  // heater control:

  digitalWrite(relay, HIGH);

  delay(au16data[4] * 10);

  digitalWrite(relay, LOW);

  delay((100 - au16data[4]) * 10 - 1);

}

   if (FAN_DUTY < HTR_CUTOFF_FAN_VAL) {

      new_levelot1 = 0;

   }

   else {

      new_levelot1 = levelOT1;

   }

  if( pac_level < HTR_CUTOFF_FAN_VAL ) { // if new levelOT2 < cutoff value then turn off OT1

    output_level_icc( 0 );

 }

 else {  // turn OT1 back on again if levelOT2 is above cutoff value. 

    output_level_icc( levelOT1 );    

// Define minimal airflow setting

#define HTR_CUTOFF_FAN_VAL 50  // stop heater if airflow goes below this value



void loop() {

  //write current thermocouple value

  au16data[2] = ((uint16_t) thermocouple.readCelsius() * 100);



  if ( au16data[5] < HTR_CUTOFF_FAN_VAL ) { //set air to minimal value to avoid overheating

    analogWrite(fan, (HTR_CUTOFF_FAN_VAL / 100.0) * 255);

  }

  else {  // set new air value

    analogWrite(fan, (au16data[5] / 100.0) * 255);

  }



  //poll modbus registers

  slave.poll( au16data, 16 );



  if ( au16data[5] < HTR_CUTOFF_FAN_VAL ) { //stop heater to avoid overheating

    digitalWrite(relay, LOW);

    delay(500);

  }

  else {  // set new heater value

    // heater control:

    digitalWrite(relay, HIGH);

    delay(au16data[4] * 10);

    digitalWrite(relay, LOW);

    delay((100 - au16data[4]) * 10 - 1);

  }



}