Published December 17, 2019 © GPL3+

Bluetooth Controlled Thermostat

I created a device that can be mounted onto the dormitory thermostats on John Brown University's campus. It is controlled by a mobile app.

IntermediateShowcase (no instructions)1 hour969

Things used in this project

Hardware components

Arduino UNO

Adafruit Feather nRF52832

SG90 Micro-servo motor

Battery, 9 V

9V Battery Clip

Breadboad Power Supply

Software apps and online services

Adafruit Bluefruit LE Connect

Hand tools and fabrication machines

Soldering iron (generic)

Solder Wire, Lead Free

3D Printer (generic)

Story

I have always been annoyed at the fact that when I get into bed every night in my dorm room, if I forget to turn my A/C on or to Cool, I have to get out of bed and go turn it on. This is especially annoying when I am in a lofted bed 6 feet off the ground and have to climb down in the pitch black. So, for a final project for a class of mine, I came up with a design for a project that will solve this problem for me. Using an Arduino, an Adafruit Feather nRF52832, 3 servo motors, a power board, a DHT11 temperature and humidity sensor, and a cellphone, I solved my problem.

Since the thermostats are mounted into the wall, and owned by the school, I could not do any physical altering of said thermostat. This meant I couldn't hardwire into the thermostat. To overcome this hurdle I decided to use 3 SG90 micro servos that would press the buttons when I told them to. The Arduino would serve as the control for these servos. Next I needed to communicate with the Arduino wirelessly. So I used an Adafruit Feather nRF52832 BLE module.

The programming for the Feather was the hardest problem to solve. I needed to store what state the thermostat was in so I went through and interconnected the button presses for the different modes the thermostat would be in. This was the user interface that would be printed out to the app on the phone. Once that was complete I connected the two boards together and used serial communication to communicate between the two boards.

The app I used was the Adafruit Bluefruit app. This app had built in control options that were already available to be used with the bluetooth module I used. I used the control pad which had up, down, right, left, 1, 2, 3, and 4 buttons on the screen with a small UART text display at the top. Button 1 controlled the power, button 2 controlled the fan speed, button 3 requested the current mode of the thermostat, up turned the temperature up, down turned the temperature down, and right progressed through the modes. The resulting code is provided as well as the circuit diagram.

In all, this project took me around 30 hours of work to complete with my experience with software and microcontrollers. It was extremely fun and satisfying to create a functioning prototype. I have even considered putting it up as an item that people at my school could order from me. The thermostat it is made to be mounted onto is the "Mitsubishi PAC-YT53CRAU-J Simple MA Remote Controller."

I will advise that anyone looking to replicate my 3D printed parts to go in an increase all measurements by about 1mm on everything except the Arduino holder and the battery pack. My tolerances were too tight therefore it was very difficult and with the imperfections of 3D printing, I had to do a lot of sanding down of parts.

Thanks for checking out my project! Leave a like if if you found my project to be interesting!

Helpful tips if you are looking to recreate this project:

Things will needed to be added onto the thermostat buttons or servo arms to allow the interaction to be proper. I used a 5V 2600 mAh battery pack with a micro usb male port on it to power the nRF52832 since mine seemed to have problems with the LiPo battery I got. That being said, you can attach a LiPo batter to the nRF52832 and get battery readings sent to the phone using pre-existing code from Adafruit. Feel free to leave a comment on this post if you try to recreate this project and run in to any problems. I will try to check this every once in a while just to see if there is any activity. Enjoy!

Schematics

Code

#include <SoftwareSerial.h>
#include <Adafruit_LittleFS.h>
#include <InternalFileSystem.h>
#include <bluefruit.h>


// OTA DFU service
BLEDfu  bledfu;
BLEBas  blebas;  // battery
BLEDis  bledis;  // device information
// Uart over BLE service
BLEUart bleuart;

// Function prototypes for packetparser.cpp
uint8_t readPacket (BLEUart *ble_uart, uint16_t timeout);
float   parsefloat (uint8_t *buffer);
void    printHex   (const uint8_t * data, const uint32_t numBytes);

// Packet buffer
extern uint8_t packetbuffer[];
int condIn = A5;
int condition = 0;

//Serial Communication to Arduino
SoftwareSerial Arduino(13, 14); //RX, TX
String inString = " "; //string to hold communication input
int Flag = 0;
int Input = 0;

//Settings Responses
int pflag = 0;

int SpeedIndex = 1;

int Ctemperature = 67;
int Htemperature = 40;
int DryTemp = 67;
int AutoTempH = 55;
int AutoTempC = 75;
int BackTempH = 55;
int BackTempC = 75;
int SetFlag = 0;
int TempFlag = 0;
int Press = 0;
int Press2 = 0;
int Press3 = 0;
int Press4 = 0;
int Press5 = 0;
int SetC = 0;
int SetH = 0;
int ModeIndex = 0;

//integer to ASCII variables
int temp = 0;
int tens = 0;
int ones = 0;
int Temp10 = 0;
int Temp1 = 0;
char bluff[] = {'0','1','2','3','4','5','6','7','8','9'}; //indexing starts at 0;

void setup(void)
{
  pinMode(condIn, INPUT);
  Serial.begin(115200);
  while ( !Serial ) delay(10);   // for nrf52840 with native usb

  Bluefruit.begin();
  Bluefruit.setTxPower(4);    // Check bluefruit.h for supported values
  Bluefruit.setName("AC Controller");

  // Configure and Start Device Information Service
  bledis.setManufacturer("Josiah Heikes");
  bledis.setModel("AC Controller V1.0");
  bledis.begin();
  // To be consistent OTA DFU should be added first if it exists
  bledfu.begin();
  
  // Start BLE Battery Service
  blebas.begin();
  blebas.write(100);
  
  // Configure and start the BLE Uart service
  bleuart.begin();

  // Set up and start advertising
  startAdv();

 // Serial.println(F("Please use Adafruit Bluefruit LE app to connect in Controller mode"));
//  Serial.println(F("Then activate/use the sensors, color picker, game controller, etc!"));
//  Serial.println(); 
  Arduino.begin(115200);
  Arduino.println("This is just the beginning"); 
}

void startAdv(void)
{
  // Advertising packet
  Bluefruit.Advertising.addFlags(BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE);
  Bluefruit.Advertising.addTxPower();
  
  // Include the BLE UART (AKA 'NUS') 128-bit UUID
  Bluefruit.Advertising.addService(bleuart);

  // Secondary Scan Response packet (optional)
  // Since there is no room for 'Name' in Advertising packet
  Bluefruit.ScanResponse.addName();

  /* Start Advertising
   * - Enable auto advertising if disconnected
   * - Interval:  fast mode = 20 ms, slow mode = 152.5 ms
   * - Timeout for fast mode is 30 seconds
   * - Start(timeout) with timeout = 0 will advertise forever (until connected)
   * 
   * For recommended advertising interval
   * https://developer.apple.com/library/content/qa/qa1931/_index.html   
   */
  Bluefruit.Advertising.restartOnDisconnect(true);
  Bluefruit.Advertising.setInterval(32, 244);    // in unit of 0.625 ms
  Bluefruit.Advertising.setFastTimeout(30);      // number of seconds in fast mode
  Bluefruit.Advertising.start(0);                // 0 = Don't stop advertising after n seconds  
}


void loop(void)
{
  Arduino.listen();
  uint8_t len = readPacket(&bleuart, 500);
  if (len == 0) return;
  
  // Got a packet!
  // printHex(packetbuffer, len);

  // Buttons
  if (packetbuffer[1] == 'B') {
    uint8_t buttnum = packetbuffer[2] - '0';
    boolean pressed = packetbuffer[3] - '0';
   // Serial.print ("Button "); Serial.print(buttnum);
    if((buttnum == 1)&&pressed) {
      Arduino.write(1);
      power();
    }
    if((buttnum == 2)&&pressed) {
      Arduino.write(2);
      fan();
    }
    if((buttnum == 3)&&pressed){
      Arduino.write(3);
      CurrentMode();
    }
    if((buttnum == 4)&&pressed){
      Arduino.write(4);
    }
    if((buttnum == 5)&&pressed){
      Arduino.write(5);
      TempUP();
    }
    if((buttnum == 6)&&pressed){
      Arduino.write(6);
      TempDown();
    }
    if((buttnum == 8)&&pressed){
      Arduino.write(8);
      MODE();
    }
  }
}

void ToASCII(int Val)
{
  ones = Val%10;
  tens = (Val-ones)/10;
}
void power(){
    if(pflag == 0){
      pflag = 1;
      bleuart.write("\rPower On");
    }else{
      pflag = 0;
      bleuart.write("\rPower Off");
    }
}

void fan(){
  if(pflag == 1){
    SpeedIndex += 1;
    if(SpeedIndex > 4){
      SpeedIndex = 1;
    }
    bleuart.write("\rFan Speed: ");
    bleuart.write(bluff[SpeedIndex]);
  }else{
    bleuart.write("\rTurn Power On");
  }
}

void CurrentMode(){
  bleuart.write("\rCurrent Mode: ");
    if(ModeIndex == 0){
      bleuart.write("Cool");
    }else if(ModeIndex == 1){
      bleuart.write("Drying");
    }else if(ModeIndex == 2){
      bleuart.write("Fan");
    }else if(ModeIndex == 3){
      bleuart.write("Auto");
    }else if(ModeIndex == 4){
      bleuart.write("Set-Back");
    }else{
      bleuart.write("Heat");
    }
    if(pflag == 0){
      bleuart.write("\rPower Currently OFF");
    }
}

void TempUP(){
  if(pflag == 1){
    if(ModeIndex == 0){
      CoolingUP(Ctemperature);
      Ctemperature = temp;
    }
    if(ModeIndex == 1){
      DryTemp += 1;
      if(DryTemp > 95){
        DryTemp = 95;
        bleuart.write("\rMax Drying Temp Reached");
      }else{
        bleuart.write("\rDry Temp Set to: ");
        ToASCII(DryTemp);
        bleuart.write(bluff[tens]);bleuart.write(bluff[ones]);
      }
    }
    if(ModeIndex == 2){
      bleuart.write("\rInvalid input");
    }
    if(ModeIndex == 3){
      Press2 += 1;
      if((Press2 == 1)&&(Press4 == 0)){
        bleuart.write("\rAuto Temps(C/H): ");
        FractionDisplay(AutoTempC, AutoTempH);
        SetFlag = 1;
      }if(((Press2 > 1)||(Press4 >= 1)) && (TempFlag == 0)){
        CoolingUP(AutoTempC);
        AutoTempC = temp;
        HeatingUP(AutoTempH);
        AutoTempH = temp;
        bleuart.write("\rAuto Temps(C/H): ");
        FractionDisplay(AutoTempC,AutoTempH);
        SetFlag = 1;
      }        
        if(SetC == 1){
          CoolingUP(AutoTempC);
          AutoTempC = temp;
          bleuart.write("\rAuto Temps(C/H): ");
          FractionDisplay(AutoTempC, AutoTempH);
        }
        if(SetH == 1){
          HeatingUP(AutoTempH);
          AutoTempH = temp;
          bleuart.write("\rAuto Temps(C/H): ");
          FractionDisplay(AutoTempC, AutoTempH);
        }
      }
    if(ModeIndex == 4){
      Press3 += 1;
      if((Press3 == 1)&&(Press5 == 0)){
        bleuart.write("\rSet-Back Temps(C/H): ");
        FractionDisplay(BackTempC, BackTempH);
        SetFlag = 1;
      }else if(((Press3 > 1)||(Press5 >= 1)) && (TempFlag == 0)){
        CoolingUP(BackTempC);
        BackTempC = temp;
        HeatingUP(BackTempH);
        BackTempH = temp;
        bleuart.write("\rSet-Back Temps(C/H): ");
        FractionDisplay(BackTempC,BackTempH);
        SetFlag = 1;
      }        
        if(SetC == 1){
          CoolingUP(BackTempC);
          BackTempC = temp;
          bleuart.write("\rSet-Back Temps(C/H): ");
          FractionDisplay(BackTempC, BackTempH);
        }
        if(SetH == 1){
          HeatingUP(BackTempH);
          BackTempH = temp;
          bleuart.write("\rSet-Back Temps(C/H): ");
          FractionDisplay(BackTempC, BackTempH);
        }     
    }
    if(ModeIndex == 5){
       HeatingUP(Htemperature);
       Htemperature = temp;
    }
  }else{
    bleuart.write("\rTurn Power On");
  }
}

void TempDown(){
  if(pflag == 1){
    if(ModeIndex == 0){
      CoolingDown(Ctemperature);
      Ctemperature = temp;
    }
    if(ModeIndex == 1){
      DryTemp -= 1;
      if(DryTemp < 67){
        DryTemp = 67;
        bleuart.write("\rMin Drying Temp Reached");
      }else{
        bleuart.write("\rDry Temp Set to: ");
        ToASCII(DryTemp);
        bleuart.write(bluff[tens]);bleuart.write(bluff[ones]);
      }
    }
    if(ModeIndex == 2){
      bleuart.write("\rInvalid input");
    }
    if(ModeIndex == 3){
      Press4 += 1;
      if((Press4 == 1) && (Press2 == 0)){
        bleuart.write("\rAuto Temps(C/H): ");
        FractionDisplay(AutoTempC, AutoTempH);
        SetFlag = 1;
      }else if(((Press4 > 1)||(Press2 >= 1)) && (TempFlag == 0)){
        CoolingDown(AutoTempC);
        AutoTempC = temp;
        HeatingDown(AutoTempH);
        AutoTempH = temp;
        bleuart.write("\rAuto Temps(C/H): ");
        FractionDisplay(AutoTempC,AutoTempH);
        SetFlag = 1;
      }        
        if(SetC == 1){
          CoolingDown(AutoTempC);
          AutoTempC = temp;
          bleuart.write("\rAuto Temps(C/H): ");
          FractionDisplay(AutoTempC, AutoTempH);
        }
        if(SetH == 1){
          HeatingDown(AutoTempH);
          AutoTempH = temp;
          bleuart.write("\rAuto Temps(C/H): ");
          FractionDisplay(AutoTempC, AutoTempH);
        }
      }
    if(ModeIndex == 4){
      Press5 += 1;
      if((Press5 == 1)&&(Press3 == 1)){
        bleuart.write("\rSet-Back Temps(C/H): ");
        FractionDisplay(BackTempC, BackTempH);
        SetFlag = 1;
      }else if(((Press5 > 1)||(Press3 >= 1)) && (TempFlag == 0)){
        CoolingDown(BackTempC);
        BackTempC = temp;
        HeatingDown(BackTempH);
        BackTempH = temp;
        bleuart.write("\rSet-Back Temps(C/H): ");
        FractionDisplay(BackTempC,BackTempH);
        SetFlag = 1;
      }        
        if(SetC == 1){
          CoolingDown(BackTempC);
          BackTempC = temp;
          bleuart.write("\rSet-Back Temps(C/H): ");
          FractionDisplay(BackTempC, BackTempH);
        }
        if(SetH == 1){
          HeatingDown(BackTempH);
          BackTempH = temp;
          bleuart.write("\rSet-Back Temps(C/H): ");
          FractionDisplay(BackTempC, BackTempH);
        }     
    }
    if(ModeIndex == 5){
       HeatingDown(Htemperature);
       Htemperature = temp;
    }
  }else{
    bleuart.write("\rTurn Power On");
  }
}

void MODE(){
  if(pflag == 1){
  Press += 1;
  if(SetFlag == 1){
    bleuart.write("\rSet Individual Temps");
    if((TempFlag == 0) && (Press = 1)){
      bleuart.write("\rSet Cooling Temp");
      SetC = 1;
      SetH = 0;
      TempFlag = 1;
    }else if((TempFlag == 1) && (Press ==2)){
      bleuart.write("\rSet Heating Temp");
      SetC = 0;
      SetH = 1;
      TempFlag = 2;
    }else{
      SetFlag = 0;
      TempFlag = 0;
      SetH = 0;
    } 
  }
  if(Press == 3){
    bleuart.write("\rTemp Setting Exited");
    bleuart.write(" Press UP/Dwn To Re-enter");
    bleuart.write(" Temperature Settings");
    Press == 0;
  }else if((SetFlag == 0)&&(TempFlag == 0)){
    ModeIndex += 1;
    if(ModeIndex > 5){
      ModeIndex = 0;
    }
    bleuart.write("\rMode: ");
    bleuart.write(bluff[ModeIndex]);
    if(ModeIndex == 0){
      bleuart.write(": Cool");
    }else if(ModeIndex == 1){
      bleuart.write(": Drying");
    }else if(ModeIndex == 2){
      bleuart.write(": Fan");
    }else if(ModeIndex == 3){
      bleuart.write(": Auto");
    }else if(ModeIndex == 4){
      bleuart.write(": Set-Back");
    }else{
      bleuart.write(": Heat");
    }
    Press = 0;
  }
  }else{
    bleuart.write("\rTurn Power On");
  }
}

void HeatingUP(int Temp){
      temp = Temp + 1;
      if(temp > 83){
        temp = 83;
        bleuart.write("\rMax Heat Temp Reached");
      }else{
        ToASCII(temp);
        bleuart.write("\rHeating Temp Set to: ");
        bleuart.write(bluff[tens]);
        bleuart.write(bluff[ones]);
      }  
}

void HeatingDown(int Temp){
  temp = Temp - 1;
  if(temp < 40){
    temp = 40;
    bleuart.write("\rMin Heat Temp Reached");
  }else{
    ToASCII(temp);
    bleuart.write("\rHeating Temp Set to: ");
    bleuart.write(bluff[tens]);
    bleuart.write(bluff[ones]);
  }
}

void CoolingUP(int Temp){
     temp = Temp + 1;
      if(temp > 95){
        temp = 95;
        bleuart.write("\rMax Cool Temp Reached");
      }else{
        ToASCII(temp);
        bleuart.write("\rCooling Temp Set to: ");
        bleuart.write(bluff[tens]);
        bleuart.write(bluff[ones]);  
      }  
}

void CoolingDown(int Temp){
  temp = Temp - 1;
  if(temp < 67){
    temp = 67;
    bleuart.write("\rMin Cool Temp Reached");
  }else{
    ToASCII(temp);
    bleuart.write("\rCooling Temp Set to: ");
    bleuart.write(bluff[tens]);
    bleuart.write(bluff[ones]);
  }
}

void FractionDisplay(int Temp1, int Temp2){
      ToASCII(Temp1);
      bleuart.write(bluff[tens]);
      bleuart.write(bluff[ones]);
      bleuart.write("/");
      ToASCII(Temp2);
      bleuart.write(bluff[tens]);
      bleuart.write(bluff[ones]);  
}

#include <SoftwareSerial.h>
#include <dht.h>
#include <Servo.h>
dht DHT;

#define DHT11_PIN 2
Servo Powerservo;
Servo Tempservo;
Servo ModeServo;

int up = 80;

int power = 140;
int Pflag = 0;
int fan = 25;

int temp = 22;
int humid = 40;
int tempup = 25;
int tempdown = 140;

int mode = 25;

String inString = "";    // string to hold input
int counter = 0;
int counter2 = 0;
int minute = 0;

//Serial Com to BLE Module
SoftwareSerial Feather(3, 4); //RX, TX

void setup(){
  Powerservo.attach(9);  // attaches the servo on pin 9 to the servo object
  Tempservo.attach(10);
  ModeServo.attach(11);
  
  Serial.begin(115200);
  while(!Serial){;}
  
  Feather.begin(115200);
}

void loop()
{
  Feather.listen();
  while(Feather.available()> 0) {
    char inByte = Feather.read();
    if(inByte == 1){
      Power();
    }
    if(inByte == 2){
      Fan();
    }
    if (inByte == 3){
      Feather.write(temp);
    }
    if(inByte == 4){
      Feather.write(humid);
    }
    if(inByte == 5){
      TempUP();
    }
    if(inByte == 6){
      TempDOWN();
    }
    if(inByte == 8){
      MODE();
    }
    Serial.println(inByte);
  }
  
  timer();
  if(minute = 1){
    Sensor();
  }
}

void Power(){
  Powerservo.write(power);
  delay(150);
  Powerservo.write(up);
  if(Pflag = 1){
    Pflag = 0;
  }else{
    Pflag = 0;
  }
}

void Fan(){
  Powerservo.write(fan);
  delay(150);
  Powerservo.write(up);
}

void TempUP(){
  Tempservo.write(tempup);
  delay(150);
  Tempservo.write(up);
}

void TempDOWN(){
  Tempservo.write(tempdown);
  delay(150);
  Tempservo.write(up);
}

void MODE(){
  ModeServo.write(mode);
  delay(150);
  ModeServo.write(up);
}


void Sensor(){
  int chk = DHT.read11(DHT11_PIN);
  delay(100);
  temp = DHT.temperature;
  humid = DHT.humidity;
  minute = 0;
}

void timer(){
  counter += 1;
  if(counter = 1000){
    counter2 += 1;
    counter = 0;
  }
  if(counter2 = 600){
    counter2 = 0;
    minute = 1;
  }
}

Credits

Josiah Heikes

1 project • 0 followers

Bluetooth Controlled Thermostat

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Custom parts and enclosures

Wall Mount for Project

Schematics

Circuit Diagram

Code

Adafruit Feather Code

Arduino Code

Credits

Josiah Heikes

Comments

Embed the widget on your own site

Bluetooth Controlled Thermostat

Bluetooth Controlled Thermostat

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Custom parts and enclosures

Wall Mount for Project

Schematics

Circuit Diagram

Code

Adafruit Feather Code

Arduino Code

Credits

Josiah Heikes

Comments

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