Reading a potentiometer in Arduino - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to read the analog value from the potentiometer.

Arduino

int sensorValue = analogRead([1]);

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

A5

B13

CA0

DLED_BUILTIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using a digital pin number instead of an analog pin.

Using the built-in LED pin instead of the analog input.

The potentiometer is connected to analog pin A0, so we use analogRead(A0) to read its value.

2fill in blank

medium

Complete the code to print the potentiometer value to the Serial Monitor.

Arduino

Serial.println([1]);

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

ApotValue

BsensorValue + 1

CanalogRead(A0)

DsensorValue

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to print the function call instead of the variable.

Using a variable name that was not declared.

We print the variable sensorValue which stores the potentiometer reading.

3fill in blank

hard

Fix the error in the setup function to initialize serial communication.

Arduino

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

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

A96000

B9600

C960

D115200

Attempts:

3 left

💡 Hint

Common Mistakes

Using an incorrect baud rate that causes communication failure.

Typing the baud rate with missing zeros.

The standard baud rate for serial communication is 9600 bits per second.

4fill in blank

hard

Fill both blanks to create a loop that reads and prints the potentiometer value repeatedly.

Arduino

void loop() {
  int sensorValue = analogRead([1]);
  Serial.println([2]);
  delay(500);
}

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

AA0

BsensorValue

CA1

DpotValue

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong pin number.

Printing a variable that was not declared.

The potentiometer is connected to pin A0, and we print the variable sensorValue that stores the reading.

5fill in blank

hard

Fill all three blanks to map the potentiometer value to a range from 0 to 255 and print it.

Arduino

int sensorValue = analogRead([1]);
int outputValue = map(sensorValue, [2], 1023, 0, 255);
Serial.println([3]);

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

AA0

B0

CoutputValue

D512

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong pin for reading.

Using an incorrect minimum value in the map function.

Printing the wrong variable.

The potentiometer is read from pin A0. The map function converts the 0-1023 range to 0-255. We print the mapped value outputValue.

Practice

1. What does the analogRead(pin) function do when reading a potentiometer on Arduino?

easy

A. It reads the voltage level on the analog pin and returns a value from 0 to 1023.

B. It sets the output voltage of the pin to control the potentiometer.

C. It converts a digital signal to an analog voltage.

D. It resets the potentiometer to zero position.

Solution

1. Step 1: Understand analogRead function

   The analogRead(pin) reads the voltage on the specified analog pin and converts it to a number between 0 and 1023.

2. Step 2: Relate to potentiometer reading

   Since a potentiometer outputs a variable voltage depending on its position, analogRead returns a value representing that voltage level.

3. Final Answer:

   It reads the voltage level on the analog pin and returns a value from 0 to 1023. -> Option A

4. Quick Check:

   analogRead() returns 0-1023 value [OK]

Hint: Remember analogRead returns 0-1023 for voltage levels [OK]

Common Mistakes:

• Thinking analogRead sets voltage instead of reading it
• Confusing analogRead with digitalRead
• Assuming analogRead returns voltage in volts

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

easy

A. sensorValue = analogWrite(A0);

B. sensorValue = digitalRead(A0);

C. sensorValue = analogRead(A0);

D. sensorValue = readAnalog(A0);

Solution

1. Step 1: Identify correct function for analog input

   The function to read analog input is analogRead(pin), not digitalRead or analogWrite.

2. Step 2: Check variable assignment syntax

   Assigning the result of analogRead(A0) to sensorValue uses the syntax: sensorValue = analogRead(A0);

3. Final Answer:

   sensorValue = analogRead(A0); -> Option C

4. Quick Check:

   Use analogRead() to read analog pin [OK]

Hint: Use analogRead(pin) to read analog sensors [OK]

Common Mistakes:

• Using digitalRead instead of analogRead
• Using analogWrite which is for output
• Using a non-existent function readAnalog

3. What will be printed on the Serial Monitor when the following Arduino code runs and the potentiometer is turned to mid position?

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

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

medium

A. A value close to 0 printed every second

B. A value close to 1023 printed every second

C. No output because Serial.begin is missing

D. A value close to 512 printed every second

Solution

1. Step 1: Understand analogRead output range

   The potentiometer at mid position outputs about half the voltage, so analogRead(A0) returns around 512 (half of 1023).

2. Step 2: Analyze Serial output

   The code prints the sensorValue every 1000 milliseconds (1 second), so the Serial Monitor shows a value near 512 each second.

3. Final Answer:

   A value close to 512 printed every second -> Option D

4. Quick Check:

   Mid potentiometer = ~512 output [OK]

Hint: Mid potentiometer gives about half max value 512 [OK]

Common Mistakes:

• Expecting 0 or 1023 at mid position
• Forgetting Serial.begin causes no output
• Confusing analogRead with digitalRead values

4. The following code is intended to read a potentiometer and print its value, but it does not work correctly. What is the error?

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

void loop() {
  int sensorValue;
  sensorValue = analogRead(0);
  Serial.print(sensorValue);
  delay(500);
}

medium

A. Missing Serial.println instead of Serial.print

B. Serial.begin baud rate is too low

C. No delay after Serial.print

D. Using analogRead(0) instead of analogRead(A0)

Solution

1. Step 1: Check Serial output method

   The code uses Serial.print(sensorValue) without a newline, causing consecutive values to print on the same line and appear garbled or unreadable.

2. Step 2: Use println for readability

   Serial.println(sensorValue) adds a newline after each value, making the output clear on the Serial Monitor.

3. Final Answer:

   Missing Serial.println instead of Serial.print -> Option A

4. Quick Check:

   Serial.print vs println for newlines [OK]

Hint: Use Serial.println() not print() for readable output [OK]

Common Mistakes:

• Using numeric 0 instead of A0 for analogRead
• Confusing Serial.print and Serial.println
• Ignoring delay causing fast output

5. You want to read a potentiometer and map its 0-1023 value to a 0-255 range to control LED brightness using PWM on pin 9. Which code snippet correctly does this?

hard

A. int sensorValue = analogRead(9);
int brightness = map(sensorValue, 0, 255, 0, 1023);
analogWrite(A0, brightness);

B. int sensorValue = analogRead(A0);
int brightness = map(sensorValue, 0, 1023, 0, 255);
analogWrite(9, brightness);

C. int sensorValue = digitalRead(A0);
int brightness = sensorValue * 255;
analogWrite(9, brightness);

D. int sensorValue = analogRead(A0);
int brightness = sensorValue / 4;
digitalWrite(9, brightness);

Solution

1. Step 1: Read potentiometer value correctly

   Use analogRead(A0) to get a value from 0 to 1023.

2. Step 2: Map value to 0-255 for PWM

   Use map(sensorValue, 0, 1023, 0, 255) to convert the range for LED brightness.

3. Step 3: Write PWM value to LED pin

   Use analogWrite(9, brightness) to set LED brightness on pin 9.

4. Final Answer:

   int sensorValue = analogRead(A0); int brightness = map(sensorValue, 0, 1023, 0, 255); analogWrite(9, brightness); -> Option B

5. Quick Check:

   Read analog, map range, write PWM [OK]

Hint: Use map() to convert 0-1023 to 0-255 for PWM [OK]

Common Mistakes:

• Using digitalRead instead of analogRead
• Writing PWM to analog pin or wrong pin
• Using digitalWrite for PWM control