Bluetooth: App not receiving data from Arduino HC-05

[robotinkerer23]

Hello, I am making a joystick-controlled robotic car for my project. When an obstacle is detected by the ultrasonic sensors, it should send this data to the mobile app and the app will produce a sound to alert the user.

I am having issues with the app not receiving the data which is sent by the Arduino.

To test a simple scenario, I just want the app to make a 'beep' sound when the joystick is pressed. The Arduino IDE will Serial.println("j") just fine, but it is somehow not received by the app. I watched tutorials which used call BluetoothClient1.BytesAvailableToReceive > 0 but it didn't work. I changed the value to > -1 and got some progress. But still, it is not producing the sound when the joystick is pressed.

I am in need of help and I greatly appreciate any assistance I can get. Thank you

#include <Joystick.h>

#include <AxisJoystick.h>

#include <AFMotor.h>

#include <NewPing.h>

AF_DCMotor motor1(1);

AF_DCMotor motor2(2);

AF_DCMotor motor3(3);

AF_DCMotor motor4(4);

//jotstick pins

#define joystick_SWPIN A10

#define joystick_XPIN A8

#define joystick_YPIN A9

//ultrasonic sensor #1 (front center)

#define TRIG1 22

#define ECHO1 24

//ultrasonic sensor #2 (left side)

#define TRIG2 26

#define ECHO2 28

//ultrasonic sensor #3 (right side)

#define TRIG3 30

#define ECHO3 32

//for car movement

int speeds = 100;

Joystick* joystick;

unsigned long debounceDuration = 50;

unsigned long lastTimeButtonStateChanged = 0;

byte lastButtonState = 0; //released

byte MovementMode = 0; //0=translation, 1=rotation

//initiate ultrasonic sensors

NewPing US1(TRIG1, ECHO1, 200);

NewPing US2(TRIG2, ECHO2, 200);

NewPing US3(TRIG3, ECHO3, 200);

void setup()

{

  Serial.begin(9600);

  joystick = new AxisJoystick(joystick_SWPIN, joystick_XPIN, joystick_YPIN);

  motor1.setSpeed(speeds);

  motor2.setSpeed(speeds);

  motor3.setSpeed(speeds);

  motor4.setSpeed(speeds);

  motor1.run(RELEASE);

  motor2.run(RELEASE);

  motor3.run(RELEASE);

  motor4.run(RELEASE);

  pinMode(joystick_SWPIN, INPUT_PULLUP);

}

void loop()

{

  int US1_distance = US1.ping_cm();

  int US2_distance = US2.ping_cm();

  int US3_distance = US3.ping_cm();

  /*

  Serial.print("Distance US1: ");

  Serial.print(US1_distance);

  Serial.print(" cm\n");

  delay(50);

  Serial.print("Distance US2: ");

  Serial.print(US2_distance);

  Serial.print(" cm\n");

  delay(50);

  Serial.print("Distance US3: ");

  Serial.print(US3_distance);

  Serial.print(" cm\n");

  delay(50);

  */

  //int obstacle = checkdistance(distanceInCm);

  if(MovementMode == 0) //MODE: TRANSLATION

  {

    if(joystick->readVRx()==0 && joystick->readVRy()>=253 && joystick->readVRy()<=759)

    {

      //Serial.println("UP");

      if(checkfront(US1_distance) == 0) //no obstacle

      {

        forward();

      }

      else

      {

        //Serial.println("OBSTACLE FRONT");

        stop();

      }

    }

    if(joystick->readVRx()==1023 && joystick->readVRy()>=253 && joystick->readVRy()<=759)

    {

      //Serial.println("DOWN");

      backward();

    }

    if(joystick->readVRx()>=253 && joystick->readVRx()<=739 && joystick->readVRy()==1023)

    {

      //Serial.println("LEFT");

     

      if(checkleft(US2_distance) == 0)

      {

        left();

      }

      else

      {

        //Serial.println("OBSACLE LEFT");

        stop();

      }

    }

    if(joystick->readVRx()>=253 && joystick->readVRx()<=759 && joystick->readVRy()==0)

    {

      //Serial.println("RIGHT");

      if(checkright(US3_distance) == 0)

      {

        right();

      }

      else

      {

        //Serial.println("OBSACLE RIGHT");

        stop();

      }

    }

    if(joystick->readVRx()>=0 && joystick->readVRx()<=253 && joystick->readVRy()>=0 && joystick->readVRy()<=253)

    {

      //Serial.println("FORWARD RIGHT");

      forwardright();

    }

    if(joystick->readVRx()>=0 && joystick->readVRx()<=253 && joystick->readVRy()>=759 && joystick->readVRy()<=1023)

    {

      //Serial.println("FORWARD LEFT");

      forwardleft();

    }

    if(joystick->readVRx()>=739 && joystick->readVRx()<=1023 && joystick->readVRy()>=759 && joystick->readVRy()<=1023)

    {

      //Serial.println("BACKWARDS LEFT");

      backwardleft();

    }

    if(joystick->readVRx()>=759 && joystick->readVRx()<=1023 && joystick->readVRy()>=0 && joystick->readVRy()<=253)

    {

      //Serial.println("BACKWARDS RIGHT");

      backwardright();

    }

  }

  else //MODE: ROTATION

  {

    if(joystick->readVRx()>=253 && joystick->readVRx()<=739 && joystick->readVRy()==1023)

    {

      //Serial.println("ROTATE LEFT");

      rotateleft();

    }

    if(joystick->readVRx()>=253 && joystick->readVRx()<=759 && joystick->readVRy()==0)

    {

      //Serial.println("ROTATE RIGHT");

      rotateright();

    }

  }

  unsigned long timeNow = millis();

 

  if(timeNow - lastTimeButtonStateChanged > debounceDuration)

  {

    byte buttonState = joystick->isPress();

    if(buttonState != lastButtonState)

    {

      lastTimeButtonStateChanged = timeNow;

      lastButtonState = buttonState;

      if(buttonState == 0) //button has been released

      {

        MovementMode = (MovementMode == 0) ? 1 : 0;

        //send to serial button has been pressed

        Serial.println("j");

      }

    }

  }

  if (moveTitle(joystick->multipleRead()) == "NOT")

  {

    //Serial.println("STOP");

    stop();

  }

}

String moveTitle(const Joystick::Move move)

{

  switch (move)

  {

    case Joystick::Move::NOT:

      return "NOT";

    case Joystick::Move::PRESS:

      return "PRESS";

    case Joystick::Move::UP:

      return "LEFT";

    case Joystick::Move::DOWN:

      return "RIGHT";

    case Joystick::Move::RIGHT:

      return "DOWN";

    case Joystick::Move::LEFT:

      return "UP";

    default:

      return "???";

  }

}

int checkfront(int US1_distance)

{

  if(US1_distance > 20 || US1_distance == 0) //no obstacle

  {

    return 0;

  }

  else //got obstacle

  {

    return 1;

  }

}

int checkleft(int US2_distance)

{

  if(US2_distance > 20 || US2_distance == 0) //no obstacle

  {

    return 0;

  }

  else //got obstacle

  {

    return 1;

  }

}

int checkright(int US3_distance)

{

  if(US3_distance > 20 || US3_distance == 0) //no obstacle

  {

    return 0;

  }

  else //got obstacle

  {

    return 1;

  }

}

void stop(){

  motor1.run(RELEASE);

  motor2.run(RELEASE);

  motor3.run(RELEASE);

  motor4.run(RELEASE);

}

void forward() {

  motor1.run(FORWARD);

  motor2.run(FORWARD);

  motor3.run(FORWARD);

  motor4.run(FORWARD);

}

void backward() {

  motor1.run(BACKWARD);

  motor2.run(BACKWARD);

  motor3.run(BACKWARD);

  motor4.run(BACKWARD);

}

void right() {

  motor1.run(BACKWARD);

  motor2.run(FORWARD);

  motor3.run(BACKWARD);

  motor4.run(FORWARD);

}

void left() {

  motor1.run(FORWARD);

  motor2.run(BACKWARD);

  motor3.run(FORWARD);

  motor4.run(BACKWARD);

}

void forwardright() {

  motor1.run(RELEASE);

  motor2.run(FORWARD);

  motor3.run(RELEASE);

  motor4.run(FORWARD);

}

void forwardleft() {

  motor1.run(FORWARD);

  motor2.run(RELEASE);

  motor3.run(FORWARD);

  motor4.run(RELEASE);

}

void backwardleft() {

  motor1.run(RELEASE);

  motor2.run(BACKWARD);

  motor3.run(RELEASE);

  motor4.run(BACKWARD);

}

void backwardright() {

  motor1.run(BACKWARD);

  motor2.run(RELEASE);

  motor3.run(BACKWARD);

  motor4.run(RELEASE);

}

void rotateleft() {

  motor1.run(BACKWARD);

  motor2.run(FORWARD);

  motor3.run(FORWARD);

  motor4.run(BACKWARD);

}

void rotateright() {

  motor1.run(FORWARD);

  motor2.run(BACKWARD);

  motor3.run(BACKWARD);

  motor4.run(FORWARD);

}

[SteveJG]

Does using your Button btn_playsound play the beep? If the sound beep does not play, where are you setting the Sound Player's source?

[robotinkerer23]

Yes, it does play the beep. I tested it by creating a button press which will play the sound and it works.

[SteveJG]

Great, then perhaps call sound_beep.Play at the arrow in the image?''

might work.

[robotinkerer23]

Unfortunately the code does not even go to that branch, it goes to the yellow 'cant detect' statement. My problem is less to do with the sound not playing, and more with the code not being able to return TRUE for the purple block.

[uskiara]

Hi @robotinkerer23,
try by rearranging the receiving procedure like this:

The procedure "DoTheJob..." for me is dummy, here you have to implement your tasks.
The label L-Ricevuto is just for debug purposes.
Last hint: instead of looking for the exact text "j", you could relax the check by checking only the presence of a "j" in your received string.
Something like:

Once you are sure it works, you can return to the exact test (= "j").
Give it a try and let us know if it works.
Cheers.

[robotinkerer23]

Hi @uskiara ,
I have followed your suggestions but alas, the app is still not producing a sound when I press my joystick button. Here is the full code in MIT app inventor: (note, the btn_playsound is just for testing to ensure that a sound actually plays. it is not part of the final app)

Here is the serial output (9600) in Arduino IDE:

Here is the application interface with the textbox used to debug:

P.S. I wonder if I need to declare the bluetooth pins or install any library in Arduino IDE? My assumption is the Bluetooth module is working fine since there is no problem in establishing connection (as seen in the app interface), and several YouTube tutorials I watched did not need to declare or install anything from the Arduino side.

Your help is greatly appreciated, thanks

[Anke]

Android version?
You must request / grant permissions (on Android 12+).

[ABG]

(Canned Response)
These blocks can be dragged into your Blocks Editor to request permission(s) for Bluetooth scanning and connecting. All three parts are needed.

Thanks to @Anke for the original code.
My changes include

• use of the Screen1 permission blocks to avoid the possibility of a typo
• using a TinyDB tag particular to BT permissions and only for BT permissions.

[ABG]

I normally see two Serial streams in these projects, one for debugging and one for data transfer.

[Juan_Antonio]

In Designer ClientBluetooth.DelimiterByte : 10

How can i display current 3 sensor variables from HC05 as a graph?

See this section of the Graphs Usage Guide: Bluetooth In order to import real time data via Bluetooth, the BluetoothClient component should be used either via the Source property, or the ChangeDataSource block. First, it is important to set the corresponding DelimiterByte in the BluetoothClient component (see Figure 62). This byte is used to separate each individual incoming value (which also has to be taken care of on the Bluetooth client side) [image] Figure 62: BluetoothClient DelimiterB…

In the example of @uskiara in Designer Clock Enabled.

Comment out all // Serial.println except Serial.println("j");
What do you get on your Serial Monitor when you press the joystickbutton: buttonState?

What Arduino terminals do you have the BT module connected to?

How many bauds is your HC-05 set to?

HC-05 Bluetooth. Arduino. Change baud rate 38400. Send random to app

Hello friends, To carry out applications with Bluetooth between Arduino and App Inventor, the HC-06 module is usually used. This module can only work as a client, enough for most of the projects that you will see in the tutorials, it is the most used and recommended. Default 9600. [bluetooth1] Another similar module is the HC-05, this can function as a server or a client. You may have to set the speed using AT commands to adapt it to App Inventor. It comes with 38400 baud and you will have t…

More examples:

Bluetooth HC-06. Arduino. Send. Receive. Send text file. Multitouch. Image

Hello friends, In this topic I am going to show some examples of Arduino UNO with the Bluetooth HC-06 module. I will start with simple examples and later I will put some more complicated codes.

[robotinkerer23]

In an attempt to simplify the experiment, I have made a simple circuit using an Arduino, breadboard, the same HC-05 module, and 1 ultrasonic sensor. When the ultrasonic sensor's distance is less than 20cm, the app should make a sound. I followed the YouTube tutorial here: Bluetooth Arduino RECEIVE data + Chart - YouTube [timestamp 6:13]

This is much closer to my actual project since the app is supposed to make a sound when the rc car detects an obstacle, rather than the joystick press which was just used for testing.

Sadly, the app still does not make a sound when I put my hand near the ultrasonic sensor. I suspect it may have something to do with 'ping time' (I don't know the proper term) between the sensor and the app.

In response to @Juan_Antonio , my bluetooth baud is at 9600. Just for good measure, I tried 38,400 and it did not work either. My bluetooth is connected to my Arduino UNO (for testing, it will be switched to Mega for final) with Tx and Rx on the opposite pins respectively.

I have yet to attempt @ABG 's suggestion on the 3-part blocks about permissions. I will update on how that goes. My Android version is 13.

Here's my simple experiment setup:

1. MIT app inventor
   

   
   
   
   

2. Arduino code and serial output (9600)

#include <NewPing.h>

#define TRIG1 5
#define ECHO1 4

//initiate ultrasonic sensors
NewPing US1(TRIG1, ECHO1, 200);

void setup() 
{
  Serial.begin(38400);
}

void loop()
{
  int US1_distance = US1.ping_cm();

  if(US1_distance > 20 || US1_distance == 0) //no obstacle
  {
    Serial.println("n");
  }
  else //got obstacle 
  {
    Serial.println("d");
  }
}

3. Phone app
   

   

4. Physical setup

Again, I appreciate all of your help, thank you.

[Juan_Antonio]

Does this code work with the ultrasonic.zip library?

Bluetooth HC-06. Arduino. Send. Receive. Send text file. Multitouch. Image

36.- Ultrasound SR04 sends distance to App by Bluetooth. pA0_Bluetooth_Arduino_Ultrasonido.aia (3.0 KB) Arduino Library Ultrasonic.zip: http://kio4.com/appinventor/9A0_Resumen_Bluetooth.htm#ultrasonido [bluetooth_basico37] #include <Ultrasonic.h> Ultrasonic ultrasonic(12,13); // (Trig PIN, Echo PIN) void setup() { Serial.begin(9600); } void loop(){ Serial.println(ultrasonic.Ranging(CM)); delay(500); } [bluetooth_basico38]

JoyStick
https://community.appinventor.mit.edu/t/bluetooth-hc-06-arduino-send-receive-send-text-file-multitouch-image/9518/23

[ABG]

Your app should show the raw data received from BlueTooth to aid in debugging.

Assign the incoming data into a global variable, and feed that variable into a Label and into your if/then testing.

Here is a logger you can add to your project to log your incoming messages into a List Picker.
https://groups.google.com/g/mitappinventortest/c/II_RlElGddU/m/J0q_E-2rAwAJ