overview port function:

Code for Arduino Nano

/*
 *  HVAC car control with Arduino
 *  Version 1.0
 *  Copyright (C) 2018  Hartmut Wendt  www.hwhardsoft.de
 *  
 *   
 *
 *  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 .
*/  


#include <OneWire.h>
#include <TimerOne.h> 


// Portkonfiguration
#define REL_VENT_FRONT 5      //relay output for ventilation front
#define REL_VENT_FOOT 6       //relay output for ventilation footwell area
#define REL_VENT_WINDOW 7     //relay output for ventilation window
#define REL_FAN_PWR 8             //relay output for fan power
#define PWM_FAN_PIN 9             //PWM output for fan power
#define REL_COMPRESSOR 11         //relay output for AC compressorr
#define REL_HEATING 12            //relay output for heating valve
#define REL_AIR_CIRCULATION 13    //relay output for air circulation
#define REL_FOG_LIGHT 14          //relay output for fog light
#define REL_HEATING_WINDOW_FRONT 15   //relay output for window heating front
#define REL_HEATING_WINDOW_REAR 16    //relay output for window heating rear
#define TEST_PIN 19               // output for sw tests

// OneWire DS18S20, DS18B20, DS1822 Temperature sensor
OneWire  sens_out(2);       // outside temperature sensor on D2
OneWire  sens_in_right(3);  // inside right side temperature sensor on D3
OneWire  sens_in_left(4);   // inside left side temperature sensor on D4

int temp_out = 20;             // measured outside temperature
int temp_in_right = 20;        // measured inside right side temperature
int temp_in_left = 20;         // measured inside left side temperature
int set_in_right = 20;        // setted inside right side temperature
int set_in_left = 20;         // setted inside left side temperature



// Variables
int i1;
char *test;
String s1;
String inputString;
boolean AC_ENABLED = false;
int bscheduler = 0;

/** Wird beim Start einmal ausgeführt */
void setup()
{
    // set port direction
    pinMode(REL_VENT_FRONT, OUTPUT);
    pinMode(REL_VENT_FOOT, OUTPUT);
    pinMode(REL_VENT_WINDOW, OUTPUT);    
    pinMode(REL_FAN_PWR, OUTPUT);
    pinMode(REL_COMPRESSOR, OUTPUT);
    pinMode(REL_HEATING, OUTPUT);
    pinMode(REL_AIR_CIRCULATION, OUTPUT);
    pinMode(REL_FOG_LIGHT, OUTPUT);
    pinMode(REL_HEATING_WINDOW_FRONT, OUTPUT);
    pinMode(REL_HEATING_WINDOW_REAR, OUTPUT);  
    pinMode(TEST_PIN, OUTPUT);  

    // init serial port for nextion communication.
    Serial.begin(9600);   
    delay(250);
    
    // first read in of temperatures
    temp_out = read_temperature(sens_out);
    delay(100);
    temp_in_right = read_temperature(sens_in_right);
    delay(100);
    temp_in_left = read_temperature(sens_in_left);
    
    //pwm init
    Timer1.initialize(1000);  // 1.000 us = 1 kHz 
    Timer1.pwm (PWM_FAN_PIN, 0);
   
}


// ----- Main loop -----------------------------------------------------------------------------------
void loop()
{
    // processing of incomming messages from nextion
    Nextion_processing();

    switch(bscheduler) 
    {

      // measure outside temperature
      case 0: 
          temp_out = read_temperature(sens_out);
          // transmit outside temperature to nextion display 
          Serial.print("ID1.val=");    
          Serial.print(temp_out);            
          Serial.write(0xff);
          Serial.write(0xff);
          Serial.write(0xff);        
          break;

      // measure inside right temperature
      case 25: 
          temp_in_right = read_temperature(sens_in_right);
          break;
          
      // measure inside left temperature
      case 50: 
          temp_in_left = read_temperature(sens_in_left);
          break;

      // HVAC control
      case 75: 
        clima_control();
        break;

      
    }
    bscheduler++;
    if (bscheduler > 100) bscheduler = 0;   

    delay(10);


}


// read temperature from a connected 1wire temperature sensor
int read_temperature...