App for Arduino+Bluetooth HC-05

We created an App in order to control an Arduino UNO via Bluetooth. The Arduino controls a servomotor and an UV LED.

Materials:

Arduino UNO

Bluetooth modul HC-05 ( for +5V)

Small Servomotor SG90

UV LED or any other LED

Circuit:

Pin connections:

App with MIT AppInventor:

For more information and tutorials visit their website:

https://appinventor.mit.edu/

We created a very simple App that has a button to connect to the Bluetooth module and three buttons as interface with the user.

APP interface:

The first part of the code searches for the Bluetooth devices that are available in your surroundings and displays a list where you can then choose your HC-05 module. Once you pick your Bluetooth module, the App will display the message „Connected“:

The second part of the code just tells the Bluetooth module which text to send depending on which Buttons the user just clicked.

Arduino code:

The main loop calls three different functions depending on the value that the Bluetooth module received. This value depends on the button that the user clicked on the interface.

IMPORTANT: while uploading the code to your Arduino, you have to disconnect the HC-05 module!

/************* www-mstronik.blog *************/
#include <Servo.h>
#include <EEPROM.h>
int servoPin = 9;
int LEDpin = 3;
char incoming_value;
int pos_adr, last_pos;
Servo mvservo;
void setup() {
  // put your setup code here, to run once:
 pos_adr = 1;
 Serial.begin(9600);
 pinMode(LEDpin, OUTPUT);
 last_pos = EEPROM.read(pos_adr);
 //mvservo.write(0);
 go_to_0();
 mvservo.attach(servoPin);
 digitalWrite (LEDpin,LOW);
 incoming_value = 3;
 }
void loop() {
  // put your main code here, to run repeatedly:
 if(Serial.available() > 0)  
  {
    incoming_value = Serial.read();      
    //Serial.print(incoming_value);        
    //Serial.print("\n");        
    switch (incoming_value){
      case '0':
        seq_1();
        read_pos();
        digitalWrite (LEDpin,LOW);
        break;
      case '1':
        seq_2();
        read_pos();
        digitalWrite (LEDpin,LOW);
        break;
      case '2':
          seq_3();
        read_pos();
        digitalWrite (LEDpin,LOW);
        break;
      case '3':
        break;
    }
    
  }     
 
}
/**************** FUNCTIONS ******************/
void read_pos(){
 int servo_last = mvservo.read();
 EEPROM.write(pos_adr, servo_last);
 last_pos = EEPROM.read(pos_adr);
}
void go_to_0(){
int xpos;
  for(xpos = last_pos; xpos>0; xpos--)
  {
    mvservo.write(xpos);
    delay(50);
  }
}
void go_to_180(){
int xpos;
  for(xpos = last_pos; xpos<180; xpos++)
  {
    mvservo.write(xpos);
    delay(50);
  }
}
void rotate_45L()
{ int xpos;
  for(xpos = 45; xpos>0; xpos--)
  {
    mvservo.write(xpos);
    delay(50);
  }
}
void rotate_45R()
{int xpos;
  for(xpos = 0; xpos < 45; xpos++)
  {
    mvservo.write(xpos);
    delay(50);
  }
}
void rot_180()
{int xpos;
  for(xpos = 180; xpos >0; xpos--)
  {
    mvservo.write(xpos);
    delay(50);
  }  
}
void seq_1(){
  digitalWrite(LEDpin,HIGH);
  go_to_180();
  rot_180();
  delay(200);
  go_to_0();
}
void seq_2(){
  digitalWrite(LEDpin,HIGH);
  rotate_45R();
  rotate_45L();
  digitalWrite(LEDpin,LOW);
  delay(500);
  digitalWrite(LEDpin,HIGH);
  rotate_45R();
  rotate_45L();
}
void seq_3(){
  digitalWrite(LEDpin,HIGH);
  rotate_45R();
  rotate_45L();
  rotate_45R();
  digitalWrite(LEDpin,LOW);
  delay(250);
  digitalWrite(LEDpin,HIGH);
  rotate_45L();
  rotate_45R();
  rotate_45L();
  digitalWrite(LEDpin,LOW);
  delay(700);
  digitalWrite(LEDpin,HIGH);
  rotate_45R();
  rotate_45L();
}

Examples:

A comet:

A haunted house: