MIT App Inventor

MIT App Inventor is a block-based programming app builder that allows us to create Android apps without coding.

I start with app inventor for this week assignment, I create the account also. Then we can create the new app

Then add the Devices setup user interface and change the customization which one I like to visualize

Add the label for the external devices bluetooth connectivity and adjust the customization also

I set the limit for the joystick butoons by using the table arrangement and made some customs

Then import the button for the joystick and arrange it properly

Address the names for the respective buttons for simple user interface

For the bluetooh connectivity I import the Bluetooth Client, it has no visualization so it only appear in the below of the phone screen for the reference

After finishing everything in the Designer section I moved on the Block section to build a program relative to my design

Step by step I import the reqiured blocks and set their fuctions and relate their working operations

This is my final block for my app to operate it

Then I came back to the design section and put out my app by .apk format

Then we can see this QR code, by using this we can download it by our smart phones

Then upload the code into Xiao board to work on Bluetooth, by using Arduino IDE I did.
I check with my phone after download it, but there is one problem I faced. All things came good but I can't connect with my Xiao board in the app I created, the name is not displayed but it showing phone's bluetooth but still I can't able to connect so I start debugging.

At first I check with the Xiao board bluetooth, there is one I find out at that time Xiao nrf52840 has only Bluetooth Low Energy, so I download the extension for the bluetooth communication - BluetoothLE
I just go through the details of that extension and understand litte bit of how it works - Link

Here we can see the downloaded extension after import it into the MIT App Inventor.
Then I change the Blockcode as well regarding the BluetoothLE.

Now again I upload the code into the Xiao nrf52840 board and check once again, but this time it shows the list of all bluetooth nearby me and I find out the XIAO name. In the code itself I named it like XIAO_BLE. I planned to work on servo motor controlling with this app, so I start setup the code and implement it.

Xiao nrf52840 code

#include <bluefruit.h>
#include <Servo.h>

BLEUart bleuart;

Servo myServo;

void setup() {

  Serial.begin(115200);

  // Attach Servo
  myServo.attach(D0);

  // Initial Position
  myServo.write(90);

  // BLE Setup
  Bluefruit.begin();

  Bluefruit.setName("XIAO_BLE");

  bleuart.begin();

  Bluefruit.Advertising.addFlags(BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE);

  Bluefruit.Advertising.addService(bleuart);

  Bluefruit.ScanResponse.addName();

  Bluefruit.Advertising.start(0);

  Serial.println("BLE Ready");
}

void loop() {

  while (bleuart.available()) {

    char cmd = bleuart.read();

    Serial.print("Received: ");
    Serial.println(cmd);

    // Forward
    if (cmd == 'F') {

      Serial.println("Rotate Forward");

      for(int pos = 90; pos <= 180; pos++) {

        myServo.write(pos);

        delay(10);
      }
    }

    // Backward
    else if (cmd == 'B') {

      Serial.println("Rotate Backward");

      for(int pos = 180; pos >= 0; pos--) {

        myServo.write(pos);

        delay(10);
      }
    }

    // Stop
    else if (cmd == 'S') {

      Serial.println("Stop Servo");

      myServo.write(90);
    }
  }
}

After connecting the Xiao board I can able to work on the app which was I created.
I made the wire connection with the Servo motor and test it.

Bluetooth Testing

The result has some good but there is some time lack only happen when I command front and back one after one, but its not much issues
Finally I succed to work on Bluetooth connection with my own app.