Sending sensor data to computer in Arduino - Mini Project: Build & Apply

Sending sensor data to computer

📖 Scenario: You have a temperature sensor connected to an Arduino board. You want to send the temperature readings to your computer so you can see them in real time.

🎯 Goal: Build a simple Arduino program that reads a temperature sensor value and sends it to the computer via the serial port.

📋 What You'll Learn

Create a variable to store the sensor pin number

Create a variable to store the sensor reading

Initialize serial communication at 9600 baud

Read the sensor value inside the loop

Send the sensor value to the computer using Serial.println

💡 Why This Matters

🌍 Real World

Sending sensor data to a computer is common in projects like weather stations, home automation, and robotics to monitor and analyze sensor readings.

💼 Career

Understanding how to read sensors and send data to a computer is a key skill for embedded systems developers, IoT engineers, and hardware programmers.

1

Set up the sensor pin

Create an integer variable called sensorPin and set it to A0 to represent the analog pin where the temperature sensor is connected.

Arduino

int sensorPin = A0;  // Your code here

Hint

The analog pins on Arduino are named A0, A1, A2, etc. Use int sensorPin = A0;.

2

Create a variable for sensor reading

Create an integer variable called sensorValue to store the reading from the sensor.

Arduino

int sensorPin = A0;
int sensorValue;  // Your code here

Hint

Just declare int sensorValue; without assigning a value yet.

3

Initialize serial communication and read sensor

Write the setup() function to start serial communication at 9600 baud using Serial.begin(9600);. Then write the loop() function to read the sensor value from sensorPin using analogRead(sensorPin) and store it in sensorValue.

Arduino

int sensorPin = A0;
int sensorValue;

void setup() {
  // Your code here
}

void loop() {
  // Your code here
}

Hint

Use Serial.begin(9600); in setup() and sensorValue = analogRead(sensorPin); in loop().

4

Send sensor data to computer

Inside the loop() function, after reading the sensor value, send it to the computer using Serial.println(sensorValue); so it appears on the serial monitor.

Arduino

int sensorPin = A0;
int sensorValue;

void setup() {
  Serial.begin(9600);
}

void loop() {
  sensorValue = analogRead(sensorPin);
  // Your code here
}

Hint

Use Serial.println(sensorValue); to send the value to the computer.

Practice

1. What is the purpose of Serial.begin(9600); in an Arduino sketch when sending sensor data to a computer?

easy

A. It reads the sensor value from analog pin 0.

B. It stops the serial communication.

C. It sends data to the sensor.

D. It starts serial communication at 9600 bits per second.

Solution

1. Step 1: Understand Serial.begin()

   Serial.begin(9600); initializes serial communication at 9600 bits per second speed.

2. Step 2: Identify its role in communication

   This function sets up the Arduino to send and receive data through the serial port to the computer.

3. Final Answer:

   It starts serial communication at 9600 bits per second. -> Option D

4. Quick Check:

   Serial.begin() = start communication [OK]

Hint: Serial.begin() always starts communication speed [OK]

Common Mistakes:

• Confusing Serial.begin() with reading sensor data
• Thinking Serial.begin() sends data
• Assuming Serial.begin() stops communication

2. Which of the following is the correct syntax to read an analog sensor connected to pin A0 and store its value in a variable named sensorValue?

easy

A. sensorValue = digitalRead(A0);

B. sensorValue = analogRead(A0);

C. sensorValue = analogWrite(A0);

D. sensorValue = Serial.read(A0);

Solution

1. Step 1: Identify the function to read analog input

   The function analogRead(pin) reads the voltage on an analog pin and returns a value between 0 and 1023.

2. Step 2: Match the correct syntax

   Using sensorValue = analogRead(A0); correctly reads the sensor on pin A0 and stores it.

3. Final Answer:

   sensorValue = analogRead(A0); -> Option B

4. Quick Check:

   analogRead() reads analog sensor [OK]

Hint: Use analogRead() for analog sensors, not digitalRead() [OK]

Common Mistakes:

• Using digitalRead() for analog sensors
• Confusing analogRead() with analogWrite()
• Trying to read sensor with Serial.read()

3. What will be the output on the serial monitor when running this Arduino code snippet?

void setup() {
  Serial.begin(9600);
}

void loop() {
  int sensorValue = analogRead(A0);
  Serial.println(sensorValue);
  delay(1000);
}

medium

A. No output because Serial.begin() is missing.

B. The digital value 0 or 1 printed every second.

C. The analog value from pin A0 printed every second.

D. A syntax error because delay() is not allowed.

Solution

1. Step 1: Analyze the code flow

   The code initializes serial communication, reads analog value from A0, prints it, then waits 1 second.

2. Step 2: Understand Serial.println() output

   Serial.println(sensorValue) sends the analog reading as a number to the serial monitor every 1000 ms.

3. Final Answer:

   The analog value from pin A0 printed every second. -> Option C

4. Quick Check:

   Serial.println(analogRead(A0)) = analog value output [OK]

Hint: Serial.println() prints values line by line [OK]

Common Mistakes:

• Thinking analogRead() returns digital 0 or 1
• Forgetting Serial.begin() causes no output
• Assuming delay() causes errors

4. Identify the error in this Arduino code that tries to send sensor data to the computer:

void setup() {
  Serial.begin(9600);
}

void loop() {
  int sensorValue = analogRead(10);
  Serial.print(sensorValue);
  delay(500);
}

medium

A. Using analogRead(10) instead of analogRead(A0).

B. Missing Serial.begin() in setup().

C. Using Serial.print() instead of Serial.println().

D. delay() cannot be used in loop().

Solution

1. Step 1: Check analogRead() parameter

   analogRead() expects an analog pin like A0, not just 10. Using 10 may cause unexpected behavior.

2. Step 2: Confirm other parts are correct

   Serial.begin() is present, Serial.print() works but prints without newline, delay() is allowed.

3. Final Answer:

   Using analogRead(10) instead of analogRead(A0). -> Option A

4. Quick Check:

   Use A0 for analogRead() pin [OK]

Hint: Use A0, A1... for analog pins, not just numbers [OK]

Common Mistakes:

• Using numeric 10 instead of A0 for analogRead()
• Thinking Serial.print() must be Serial.println()
• Believing delay() is disallowed in loop()

5. You want to send temperature sensor data from analog pin A1 to the computer every 2 seconds. Which code snippet correctly implements this?

hard

A. void setup() {
Serial.begin(9600);
}

void loop() {
int temp = analogRead(A1);
Serial.println(temp);
delay(2000);
}

B. void setup() {
Serial.begin(115200);
}

void loop() {
int temp = digitalRead(A1);
Serial.print(temp);
delay(2000);
}

C. void setup() {
Serial.begin(9600);
}

void loop() {
int temp = analogRead(1);
Serial.println(temp);
delay(1000);
}

D. void setup() {
Serial.begin(9600);
}

void loop() {
int temp = analogRead(A1);
Serial.print(temp);
delay(500);
}

Solution

1. Step 1: Check serial speed and pin reading

   Serial.begin(9600) is standard and analogRead(A1) correctly reads temperature sensor on pin A1.

2. Step 2: Verify output and delay timing

   Serial.println(temp) sends data with newline, delay(2000) waits 2 seconds as required.

3. Final Answer:

   Code snippet D correctly reads and sends data every 2 seconds. -> Option A

4. Quick Check:

   Use analogRead(A1), Serial.println(), delay(2000) [OK]

Hint: Use Serial.println() and delay(2000) for 2-second intervals [OK]

Common Mistakes:

• Using digitalRead() for analog sensor
• Wrong delay time for 2 seconds
• Using analogRead(1) instead of analogRead(A1)