Sending data over Bluetooth in Arduino - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the Bluetooth serial communication at 9600 baud rate.

Arduino

void setup() {
  Serial.begin([1]);
}

Drag options to blanks, or click blank then click option'

A4800

B115200

C9600

D19200

Attempts:

3 left

💡 Hint

Common Mistakes

Using a baud rate that does not match the Bluetooth module's setting.

Forgetting to initialize Serial communication.

The standard baud rate for Bluetooth serial communication is 9600.

2fill in blank

medium

Complete the code to send the string "Hello" over Bluetooth.

Arduino

void loop() {
  Serial.[1]("Hello");
  delay(1000);
}

Drag options to blanks, or click blank then click option'

Aprint

Bavailable

Cwrite

Dread

Attempts:

3 left

💡 Hint

Common Mistakes

Using read which is for receiving data.

Using available which checks incoming data.

The print function sends data as readable text over serial.

3fill in blank

hard

Fix the error in the code to read a character from Bluetooth and store it in variable 'c'.

Arduino

char c;
void loop() {
  if (Serial.[1]() > 0) {
    c = Serial.read();
  }
}

Drag options to blanks, or click blank then click option'

Awrite

Bbegin

Cprint

Davailable

Attempts:

3 left

💡 Hint

Common Mistakes

Using write() which sends data, not checks availability.

Using print() which sends data.

available() checks if data is ready to read from serial.

4fill in blank

hard

Fill both blanks to send the integer variable 'value' as a string over Bluetooth.

Arduino

int value = 123;
void loop() {
  Serial.[1](String([2]));
  delay(1000);
}

Drag options to blanks, or click blank then click option'

Aprint

Bvalue

Cwrite

DSerial

Attempts:

3 left

💡 Hint

Common Mistakes

Using write which sends raw bytes, not readable text.

Passing a wrong variable or object.

Use print to send text, and convert the integer value to a string.

5fill in blank

hard

Fill all three blanks to read a line from Bluetooth and store it in 'inputString'.

Arduino

String inputString = "";
void loop() {
  if (Serial.[1]() > 0) {
    char c = Serial.[2]();
    if (c == [3]) {
      // end of line
    } else {
      inputString += c;
    }
  }
}

Drag options to blanks, or click blank then click option'

Aavailable

Bread

C'\n'

Dwrite

Attempts:

3 left

💡 Hint

Common Mistakes

Using write() instead of read().

Checking for wrong end-of-line character.

Check if data is available, read one character, and detect newline '\n' as line end.

Practice

1. What is the main purpose of using Bluetooth with an Arduino?

easy

A. To connect Arduino to the internet directly

B. To increase the Arduino's processing speed

C. To send and receive data wirelessly

D. To power the Arduino without a battery

Solution

1. Step 1: Understand Bluetooth function

   Bluetooth is a wireless communication technology used to send and receive data without wires.

2. Step 2: Identify Arduino's Bluetooth use

   Arduino uses Bluetooth to communicate wirelessly with other devices, not to speed up or power itself.

3. Final Answer:

   To send and receive data wirelessly -> Option C

4. Quick Check:

   Bluetooth = wireless data transfer [OK]

Hint: Bluetooth means wireless data transfer [OK]

Common Mistakes:

• Thinking Bluetooth powers the Arduino
• Confusing Bluetooth with internet connection
• Assuming Bluetooth speeds up processing

2. Which Arduino code snippet correctly initializes a SoftwareSerial Bluetooth connection on pins 10 (RX) and 11 (TX) at 9600 baud?

easy

A. SoftwareSerial BT(11, 10); BT.begin(115200);

B. SoftwareSerial BT(11, 10); BT.begin(9600);

C. SoftwareSerial BT(10, 11); BT.begin(115200);

D. SoftwareSerial BT(10, 11); BT.begin(9600);

Solution

1. Step 1: Check pin order for SoftwareSerial

   SoftwareSerial constructor uses RX pin first, then TX pin. So (10, 11) means RX=10, TX=11.

2. Step 2: Verify baud rate matches 9600

   BT.begin(9600) sets baud rate to 9600, which is standard for many Bluetooth modules.

3. Final Answer:

   SoftwareSerial BT(10, 11); BT.begin(9600); -> Option D

4. Quick Check:

   Correct pins and baud = SoftwareSerial BT(10, 11); BT.begin(9600); [OK]

Hint: RX pin first, then TX pin in SoftwareSerial [OK]

Common Mistakes:

• Swapping RX and TX pins
• Using wrong baud rate
• Calling begin() with wrong speed

3. What will be the output on the Bluetooth receiver if the Arduino code below runs?

SoftwareSerial BT(10, 11);
void setup() {
  BT.begin(9600);
  BT.println("Hello");
}
void loop() {}

medium

A. HELLO

B. Hello

C. hello

D. No output

Solution

1. Step 1: Understand BT.println() behavior

   BT.println("Hello") sends the string "Hello" followed by a newline over Bluetooth.

2. Step 2: Check case sensitivity

   The string "Hello" is sent exactly as written, preserving case.

3. Final Answer:

   Hello -> Option B

4. Quick Check:

   BT.println("Hello") sends "Hello" [OK]

Hint: println sends exact string with newline [OK]

Common Mistakes:

• Assuming output is uppercase
• Thinking no output because loop is empty
• Confusing println with print

4. Identify the error in this Arduino Bluetooth code snippet:

SoftwareSerial BT(10, 11);
void setup() {
  Serial.begin(9600);
  BT.begin(9600);
}
void loop() {
  Serial.println("Send data");
  BT.print("Data");
}

medium

A. No error, code works fine

B. Missing BT.read() to receive data

C. Pins 10 and 11 are swapped in SoftwareSerial

D. Serial.begin() should be BT.begin() only

Solution

1. Step 1: Verify initialization

   Serial.begin(9600) initializes USB serial correctly; BT.begin(9600) initializes SoftwareSerial on pins 10 (RX), 11 (TX) correctly.

2. Step 2: Check loop behavior

   The loop sends "Send data\n" to Serial and "Data" repeatedly to Bluetooth. No syntax errors or crashes; code works fine for sending data over Bluetooth.

3. Final Answer:

   No error, code works fine -> Option A

4. Quick Check:

   Initializes correctly and sends data continuously [OK]

Hint: Code runs fine for sending; BT.read() not needed if only sending [OK]

Common Mistakes:

• Thinking Serial.begin() interferes with Bluetooth
• Believing BT.read() is always required
• Assuming pins 10 and 11 are swapped

5. You want to send sensor data from Arduino to a phone via Bluetooth every second. Which code snippet correctly implements this using SoftwareSerial on pins 2 (RX) and 3 (TX) at 9600 baud?

hard

A. SoftwareSerial BT(2, 3);
void setup() {
BT.begin(9600);
}
void loop() {
int sensorValue = analogRead(A0);
BT.println(sensorValue);
delay(1000);
}

B. SoftwareSerial BT(3, 2);
void setup() {
BT.begin(9600);
}
void loop() {
int sensorValue = analogRead(A0);
BT.print(sensorValue);
delay(1000);
}

C. SoftwareSerial BT(2, 3);
void setup() {
BT.begin(115200);
}
void loop() {
int sensorValue = analogRead(A0);
BT.println(sensorValue);
delay(1000);
}

D. SoftwareSerial BT(2, 3);
void setup() {
Serial.begin(9600);
}
void loop() {
int sensorValue = analogRead(A0);
Serial.println(sensorValue);
delay(1000);
}

Solution

1. Step 1: Verify SoftwareSerial pins and baud rate

   BT is created with RX=2 and TX=3, and BT.begin(9600) matches baud rate for Bluetooth.

2. Step 2: Check data sending and timing

   Inside loop, sensor value is read and sent with BT.println(), then delay(1000) waits 1 second.

3. Final Answer:

   SoftwareSerial BT(2, 3); void setup() { BT.begin(9600); } void loop() { int sensorValue = analogRead(A0); BT.println(sensorValue); delay(1000); } -> Option A

4. Quick Check:

   Correct pins, baud, send, and delay = SoftwareSerial BT(2, 3); void setup() { BT.begin(9600); } void loop() { int sensorValue = analogRead(A0); BT.println(sensorValue); delay(1000); } [OK]

Hint: Match pins, baud, and use println with delay [OK]

Common Mistakes:

• Swapping RX and TX pins
• Using wrong baud rate
• Sending data on Serial instead of BT