Designing a General Purpose Heat Pump Controller

[buffalobillpatrick]

Setup:

#include <Wire.h>
#include <LCD.h>
#include <LiquidCrystal_I2C.h>


#define I2C_ADDR    0x3F // <<----- Add your address here.  Find it from I2C Scanner

#define BACKLIGHT_PIN     3  //define LCD digital pins
#define En_pin  2
#define Rw_pin  1             //can't use D0 Tx & D1 Rx
#define Rs_pin  0
#define D4_pin  4
#define D5_pin  5              //can use 2 -> 12 below in code
#define D6_pin  6
#define D7_pin  7

LiquidCrystal_I2C lcd(I2C_ADDR,En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);

#define SDA                           A4  //RESERVE I2C for LCD           
#define SCL                           A5  

#define mux_analog_in                 A0  //multiplexer to Arduino analog in pin       

#define MQ2_GAS_sensor                A1     


                             // D0 = RX, D1 = TX, reserved
                                     // relays Digital output pins
#define  ALIVE_RLY_R1             4  //  D4                        Songle 10A
                                     //Split R1 & R2 into seperate groups
                                     //as songle relay coil = 90ma
                                     //each group can source 150 mA. max
                                     //group 1 ends with D4
                                     //group 2 starts with D5
#define  HP_RLY_R2                6  //  D6               CRYDOM H12D4850 50A

                                 //define Digital output pins for MUX D7 -> D11
                                 // multiplexer address select lines (A/B/C/D)
const byte mux_address_A       = 7;
const byte mux_address_B       = 8; 
const byte mux_address_C       = 9; 
const byte mux_address_D       = 10; 
const byte mux_enable          = 13;  // multiplexer enable


#define ALARM                   11  // D11 PWM OUTPUT to Audible Alarm

                        


              //analog signals into MUX, these are NOT analog pins on Arduino
                                        //These 12 have been tested good
#define SOLAR_tank_sensor            0     
#define COMP_DISCHARGE_sensor        1 

#define DSH_H2O_IN_sensor            2                        
#define DSH_H2O_OUT_sensor           3                        

#define INPUT_DEAD1           4
#define INPUT_DEAD2           5

#define IHX_HI_IN_sensor             6                        
#define IHX_HI_OUT_sensor            7 

#define IHX_LO_IN_sensor             8                        
#define IHX_LO_OUT_sensor            9 

#define SOURCE_IN_sensor            10              

#define INPUT_DEAD3          11
#define INPUT_DEAD4          12

#define SOURCE_OUT_sensor           13  

#define LOAD_IN_sensor              14                
#define LOAD_OUT_sensor             15



unsigned long T1;
unsigned long T2;
unsigned long TT;


int i;
int Sensor_Data;



void setup(void)       //Start Setup
  {
        
  pinMode (mux_analog_in, INPUT);  //MUX DATA INPUT
  pinMode (mux_address_A, OUTPUT); // multiplexer address select lines (A/B/C/D)
  pinMode (mux_address_B, OUTPUT); 
  pinMode (mux_address_C, OUTPUT); 
  pinMode (mux_address_D, OUTPUT); 
  pinMode (mux_enable,    OUTPUT); // multiplexer enable

 
  pinMode( ALARM,                       OUTPUT); //digital output to relays

  pinMode( ALIVE_RLY_R1,                OUTPUT); //digital output to relays
  pinMode( HP_RLY_R2,                   OUTPUT); //digital output to relays

  digitalWrite ( ALIVE_RLY_R1,          HIGH); //OFF
  digitalWrite ( HP_RLY_R2,             HIGH); //OFF
 
 
 // Serial.begin(9600); // start serial communication

 // delay(10000);      //time to enable monitor window
 
  
 // Serial.println(F("........Hello world!......."));
 // delay(100); 
  
  lcd.begin (16,2); //  <<----- My LCD is 16x2
  lcd.clear();
 
  //Switch on the backlight
  lcd.setBacklightPin(BACKLIGHT_PIN,POSITIVE);
  lcd.setBacklight(HIGH);
    

  digitalWrite (ALIVE_RLY_R1,   LOW);   //ON 

  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("ALIVE SIGNAL TO"));
  lcd.setCursor(0,1);
  lcd.print(F("MASTER, R1 ON"));
  delay(5000);
  // Warer pumps not started yet, so can't use custom delay 

 
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("BBP_HP_SLAVE"));
  delay(5000);
  // Warer pumps not started yet, so can't use custom delay 


  beep(50);
  beep(50);
  beep(50);
  delay(1000);

  
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("HP DELAY 20Sec"));
  lcd.setCursor(0,1);
  lcd.print(F("BEFORE STARTING"));

  for (i=0; i< 4; i++)    //delay 20 sec.
  {   
  custom_delay();     //Delay 5 sec. & Checks SRC OUT Temp & GAS
  }

 
  digitalWrite (HP_RLY_R2,          LOW);  //Power HP 
  
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("HP R2 ON"));  
  lcd.setCursor(0,1);
  lcd.print(F("END SETUP"));   
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 
                      // FOR BEING TOO COLD, RESETS RLYS & HANGS FOREVER IF SO

  }    //end setup

[buffalobillpatrick]

Forever Loop & functions:

  void loop ()
{ 
  
//  T1 = millis();
 
  Sensor_Data         =  (Read_10K_NTC (SOLAR_tank_sensor));                  
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("SOLAR TANK= "));
  lcd.print(Sensor_Data);  
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 
         
  
  Sensor_Data         =  (Read_10K_NTC (COMP_DISCHARGE_sensor));                  
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("COMP_DISCHAR="));
  lcd.print(Sensor_Data);
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 
         

  Sensor_Data          =  (Read_10K_NTC (DSH_H2O_IN_sensor));                  
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("DSH_H2O_IN="));
  lcd.print(Sensor_Data);
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 
  

  Sensor_Data          =  (Read_10K_NTC (DSH_H2O_OUT_sensor));
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("DSH_H2O_OUT="));
  lcd.print(Sensor_Data);
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 
  

  Sensor_Data        =  (Read_10K_NTC (IHX_HI_IN_sensor));
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("IHX_HI_IN="));
  lcd.print(Sensor_Data);
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 
  
  
  Sensor_Data        =  (Read_10K_NTC (IHX_HI_OUT_sensor));
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("IHX_HI_OUT="));
  lcd.print(Sensor_Data);
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 


  Sensor_Data         =  (Read_10K_NTC (IHX_LO_IN_sensor));
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("IHX_LO_IN="));
  lcd.print(Sensor_Data);
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 
     
  
  Sensor_Data        =  (Read_10K_NTC (IHX_LO_OUT_sensor));
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("IHX_LO_OUT="));
  lcd.print(Sensor_Data);
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 


  Sensor_Data       =  (Read_10K_NTC (SOURCE_IN_sensor));
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("SRC_IN="));
  lcd.print(Sensor_Data);
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 
        
 
  Sensor_Data      =  (Read_10K_NTC (SOURCE_OUT_sensor));
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("SRC_OUT="));
  lcd.print(Sensor_Data);
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 
        
  
  Sensor_Data       =  (Read_10K_NTC (LOAD_IN_sensor));
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("LOAD_IN="));
  lcd.print(Sensor_Data);
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 
        
 
  Sensor_Data       =  (Read_10K_NTC (LOAD_OUT_sensor));
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("LOAD_OUT="));
  lcd.print(Sensor_Data);
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 
         
/*
  T2 = millis();

  TT = T2 - T1;

  lcd.clear();
  lcd.home (); // go home
  lcd.print(TT);   //about 69 sec. per loop
  
  custom_delay();     //Delay 5 sec. & Checks Water SRC OUT 
                      // FOR BEING TOO COLD, RESETS RLYS & HANGS FOREVER IF SO          

*/

}  //end forever loop




void custom_delay (void) //Delay 5 sec. & Checks Water SRC OUT & GAS
{  
  #define GAS_LIMIT               100   //TBD To Be Determined with testing
  #define SOURCE_OUT_LOW_LIMIT    34
  #define sample_cnt 23                    //takes 254 MS  
  int I;  
  float alpha =   0.9;     // factor to tune
  float average = 0.0;
  
//  T1 = millis();
  
  
  delay(4513); 

  
  for (I=0; I< sample_cnt; I++) 
  {  
  average =  alpha * analogRead(MQ2_GAS_sensor) + (1-alpha) * average;
  delay(10);
  }
  
 //Test if GAS LIMIT EXCEEDED
  Sensor_Data  =  average;      //convert float to int
  
  Sensor_Data  =  map(Sensor_Data, 0, 1023, 0, 100);

/*
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("GAS SENSOR="));
  lcd.print(Sensor_Data);  
  delay(10000);
*/  
  
  if (Sensor_Data > GAS_LIMIT)     
  {  
  digitalWrite (ALIVE_RLY_R1,               HIGH); //OFF
  digitalWrite (HP_RLY_R2,                  HIGH); //OFF

  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("GAS LIMIT MET"));
  lcd.setCursor(0,1);  
  lcd.print(F("TurnOff all Rlys"));  
  delay(5000);
   
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("HANG FOREVER 1"));

  do{ beep(200);} while (I == I);  //hang  
  }  //end if GAS LIMIT 


  //Test if Source out is too cold to run HP  
  if ((Read_10K_NTC (SOURCE_OUT_sensor) <= SOURCE_OUT_LOW_LIMIT))     
  { 
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("HP SRC OUT COLD"));
  lcd.setCursor(0,1);  
  lcd.print(F("RESET ALL RELAYS"));  
  delay(5000);
   
  digitalWrite (ALIVE_RLY_R1,               HIGH); //OFF
  digitalWrite (HP_RLY_R2,                  HIGH); //OFF

  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("HANG FOREVER 2"));

  do{I = I;} while (I == I);  //hang
  
  }  //end if SOURCE_OUT is too cold 
  
/*
  T2 = millis();

  TT = T2 - T1;
  
  lcd.clear();
  lcd.home (); // go home
  lcd.print(TT);    // 5 sec
  delay(10000); 
*/

  }  //end custom_delay function  




void beep(unsigned char delayms)
{
  analogWrite(ALARM, 255);     // Almost any value can be used except 0 
                           // experiment to get the best tone
  delay(delayms);          // wait for a delayms ms
  analogWrite(ALARM, 0);       // 0 turns it off
  delay(delayms);          // wait for a delayms ms   
} 




int Read_10K_NTC (const byte which_sensor)
  {   
  #define sample_cnt 23                    //takes 254 MS
  
  float alpha =   0.9;     // factor to tune
  float average = 0.0;
  
  int I;
 
  float steinhart;

// resistance at 25 degrees C
#define THERMISTORNOMINAL 10000

// temp. for nominal resistance (almost always 25 C)
#define TEMPERATURENOMINAL 25

// The beta coefficient of the thermistor (usually 3000-4000)
#define BCOEFFICIENT 3892

// the value of the series resistor
#define SERIESRESISTOR 10000



//  T1 = millis();



  digitalWrite (mux_enable, HIGH); //disable
  delay(10);

  // select correct MUX channel
  digitalWrite (mux_address_A, (which_sensor & 1) ? HIGH : LOW);
  digitalWrite (mux_address_B, (which_sensor & 2) ? HIGH : LOW);
  digitalWrite (mux_address_C, (which_sensor & 4) ? HIGH : LOW);
  digitalWrite (mux_address_D, (which_sensor & 8) ? HIGH : LOW);

  digitalWrite (mux_enable, LOW); //enable
  delay(10);


  
  for (I=0; I< sample_cnt; I++) 
  {  
  average =  alpha * analogRead(mux_analog_in) + (1-alpha) * average;
  delay(10);
  }
  
  // convert the value to resistance
  average = 1023 / average - 1;
  average = SERIESRESISTOR / average;
  steinhart = average / THERMISTORNOMINAL;     // (R/Ro)
  steinhart = log(steinhart);                  // ln(R/Ro)
  steinhart /= BCOEFFICIENT;                   // 1/B * ln(R/Ro)
  steinhart += 1.0 / (TEMPERATURENOMINAL + 273.15); // + (1/To)
  steinhart = 1.0 / steinhart;                 // Invert
  steinhart -= 273.15;                         // convert to C
  
  return (round(steinhart * 1.8) + 32);       // round to whole number 
                                              // & convert to F            

/*
  T2 = millis();

  TT = T2 - T1;
  
  lcd.clear();
  lcd.home (); // go home
  lcd.print(TT);    // 5 sec
  delay(10000); 
*/
           
  }  // end of Read_10K_NTC

[takyka]

buffalobillpatrick,

Nice, simple code. If you don't mind, I would share with you my complains strictly from remidial intent.

- As you handle strings, you will exhaust RAM very fast. All strings are copied from flash to RAM at startup. you should use F() macro to keep strings in flash. Like this. lcd.print(F("COMP_TEMP = "));
look here for details

- With temperature displaying, you block the program for 90secs. It's enough time to freeze your BPHX if you are not lucky.

I would recommend you to modify the code to have non blocking delays in your code. Or make a custom delay function, which continously measure temperatures and evaluates critical conditions.

Much nicer averaging can be done by doing AD conversion repeatedly like below logic:

tempX=tempX+(K*(readSensor_F(X)-tempX)) where K<1.
By changing the value of K you can control, how much averaging you want. K=1 no averaging, smaller and smaller K means bigger and bigger averaging.

For on/off control I would recommend to control Arduino's reset pin, not the supply voltage. This way you can detect short interruptions in the control signal too.

T.

[buffalobillpatrick]

Thanks takyka, that dropped my RAM use by 21%

With these 10K NTC Thermisters the readings don't bounce around, that averaging is really not needed.

I need to study on "tempX=tempX+(K*(readSensor_F(X)-tempX)) where K<1"

On the Reset pin vs. Power on/off The Master Heat System controller would have to hold the Slave reset pin LOW for months at a time, While Slave is wasting power.

Also if I need to reset the Master then the Slave would start running HP when not needed.

Good Point on "- With temperature displaying, you block the program for 90secs. It's enough time to freeze your BPHX if you are not lucky."

In my case I'm using 4 Ton Coax HX's

[buffalobillpatrick]

takkyka, GREAT idea on the "custom delay"

custom_delay(); //function call example

void custom_delay (void) //Delay 5 sec. & Checks Water SRC OUT & GAS
{  
  #define GAS_LIMIT               100   //TBD To Be Determined with testing
  #define SOURCE_OUT_LOW_LIMIT    34
  #define sample_cnt 23                    //takes 254 MS  
  int I;  
  float alpha =   0.9;     // factor to tune
  float average = 0.0;
  
//  T1 = millis();
  
  
  delay(4513); 

  
  for (I=0; I< sample_cnt; I++) 
  {  
  average =  alpha * analogRead(MQ2_GAS_sensor) + (1-alpha) * average;
  delay(10);
  }
  
 //Test if GAS LIMIT EXCEEDED
  Sensor_Data  =  average;      //convert float to int
  
  Sensor_Data  =  map(Sensor_Data, 0, 1023, 0, 100);

/*
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("GAS SENSOR="));
  lcd.print(Sensor_Data);  
  delay(10000);
*/  
  
  if (Sensor_Data > GAS_LIMIT)     
  {  
  digitalWrite (ALIVE_RLY_R1,               HIGH); //OFF
  digitalWrite (HP_RLY_R2,                  HIGH); //OFF

  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("GAS LIMIT MET"));
  lcd.setCursor(0,1);  
  lcd.print(F("TurnOff all Rlys"));  
  delay(5000);
   
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("HANG FOREVER 1"));

  do{ beep(200);} while (I == I);  //hang  
  }  //end if GAS LIMIT 


  //Test if Source out is too cold to run HP  
  if ((Read_10K_NTC (SOURCE_OUT_sensor) <= SOURCE_OUT_LOW_LIMIT))     
  { 
  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("HP SRC OUT COLD"));
  lcd.setCursor(0,1);  
  lcd.print(F("RESET ALL RELAYS"));  
  delay(5000);
   
  digitalWrite (ALIVE_RLY_R1,               HIGH); //OFF
  digitalWrite (HP_RLY_R2,                  HIGH); //OFF

  lcd.clear();
  lcd.home (); // go home
  lcd.print(F("HANG FOREVER 2"));

  do{I = I;} while (I == I);  //hang
  
  }  //end if SOURCE_OUT is too cold 
  
/*
  T2 = millis();

  TT = T2 - T1;
  
  lcd.clear();
  lcd.home (); // go home
  lcd.print(TT);    // 5 sec
  delay(10000); 
*/

  }  //end custom_delay function  




void beep(unsigned char delayms)
{
  analogWrite(ALARM, 255);     // Almost any value can be used except 0 
                           // experiment to get the best tone
  delay(delayms);          // wait for a delayms ms
  analogWrite(ALARM, 0);       // 0 turns it off
  delay(delayms);          // wait for a delayms ms   
}

[buffalobillpatrick]

On my much larger & more complicated HEAT_SYS_MASTER program,

takyka's advice to use F() syntax to keep fixed character strings in Flash
saved 50% of dynamic memory at a cost of 1% of program storage space.

Why don't Arduino IDE do this automatically???

[AC_Hacker]

Originally Posted by buffalobillpatrick

On my much larger & more complicated HEAT_SYS_MASTER program,

takyka's advice to use F() syntax to keep fixed character strings in Flash
saved 50% of dynamic memory at a cost of 1% of program storage space.

Why don't Arduino IDE do this automatically???

Arduino is open source, my friend. YOU are Arduino.

Need I say more?

-AC

[AC_Hacker]

My LCD display arrived yesterday.

I have even gotten the spec sheets and wiki sources & Arduino library resources bookmarked.

Looks pretty nice! I can see why jeff5may would go for this one. I did notice that according to notes on the DFRobot page, there still seem to be some lingering issues with the LED light.

Am I correct that we are still going with the Uno, and the 4-way relay shield board?

In my heart of hearts, I would prefer to use SSRs instead of mechanical relays, but relays are cheap & good for now.

jeff5may, soon as I hear from you, I'll go ahead and order the processor board and relay shield.

It'll be great fun to build a test bed and start running various program versions.

Best,

-AC

[AC_Hacker]

After carefully appreciating the new LCD display, I went upstairs and dug about in my parts box and found an Arduino duemilanove, which looks to be functionally identical to the Uno R3... correct me if I'm wrong.

Then I fit the LCD display to the Arduino... everything lined up nicely.

This is a pretty nice looking combo!. I noticed that there was one hole that both boards share in common, apparently to put a screw through so their mechanical connection is a little more secure. Two holes would make me happier.

So, jeff5may... is your LCD sketch ready to see daylight??

Also, I just ordered the afore mentioned relay shield from amazon... they ship pretty fast.

Best,

-AC

[jeff5may]

Originally Posted by AC_Hacker

After carefully appreciating the new LCD display, I went upstairs and dug about in my parts box and found an Arduino duemilanove, which looks to be functionally identical to the Uno R3... correct me if I'm wrong.

Then I fit the LCD display to the Arduino... everything lined up nicely.

This is a pretty nice looking combo!. I noticed that there was one hole that both boards share in common, apparently to put a screw through so their mechanical connection is a little more secure. Two holes would make me happier.

So, jeff5may... is your LCD sketch ready to see daylight??

Also, I just ordered the afore mentioned relay shield from amazon... they ship pretty fast.

Best,

-AC

There is a workaround for the LCD keypad Shields that will work with them all whether they have the flaw or not. I have integrated it into my sketch . it's not finished yet, but I can get it to a point where I can post something that will be useful to load and run quickly. I will post the project on github or google code so that you all can help me with it and not pollute this thread.