ADC resolution (10-bit, 0-1023 range) in Arduino - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to read an analog value from pin A0.

Arduino

int sensorValue = analogRead([1]);

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

AA0

B13

C0

DLED_BUILTIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using a digital pin number instead of an analog pin name.

Using 0 instead of A0, which is not recognized as analog pin.

The analogRead function reads the voltage on the specified analog pin. Pin A0 is the first analog input pin on Arduino.

2fill in blank

medium

Complete the code to convert the analog reading to a voltage (0-5V).

Arduino

float voltage = sensorValue * ([1] / 1023.0);

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

A5.0

B3.3

C10.0

D12.0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 3.3 instead of 5.0 volts for boards with 5V reference.

Dividing by 1024 instead of 1023.

The Arduino analog reference voltage is usually 5.0 volts. We multiply the reading by 5.0 and divide by 1023 to get the voltage.

3fill in blank

hard

Fix the error in the code to print the voltage with two decimal places.

Arduino

Serial.println([1], 2);

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

AsensorValue

Bvoltage

C5.0

DanalogRead(A0)

Attempts:

3 left

💡 Hint

Common Mistakes

Printing sensorValue instead of voltage.

Passing a constant like 5.0 instead of a variable.

To print the voltage with two decimal places, we use the variable 'voltage' which holds the converted value.

4fill in blank

hard

Fill both blanks to loop over analog pins A0-A5 and print readings greater than 500.

Arduino

for(int [1] = 0; [1] < 6; [1]++) {
  int value = analogRead([2]);
  if (value > 500) {
    Serial.print("Pin A");
    Serial.print([1]);
    Serial.print(": ");
    Serial.println(value);
  }
}

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

Ai

BA0

CA0 + i

Dpin

Attempts:

3 left

💡 Hint

Common Mistakes

Using a fixed pin like A0 inside the loop.

Using an undefined variable for the pin.

We use 'i' as the loop variable and 'A0 + i' to read analog pins A0 to A5.

5fill in blank

hard

Fill all three blanks to calculate and print the percentage of the maximum ADC value.

Arduino

int maxValue = [1];
int reading = analogRead(A0);
float percentage = (reading * 100.0) / [2];
Serial.print([3]);
Serial.println("%");

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

A1023

Cpercentage

D500

Attempts:

3 left

💡 Hint

Common Mistakes

Using 500 instead of 1023 as max ADC value.

Printing the wrong variable instead of percentage.

The maximum ADC value for 10-bit resolution is 1023. We use it to calculate the percentage and print the 'percentage' variable.

Practice

1. What is the maximum value returned by analogRead() on a 10-bit ADC in Arduino?

easy

A. 1023

B. 255

C. 512

D. 4095

Solution

1. Step 1: Understand ADC bit resolution

   A 10-bit ADC means it can represent values from 0 to 2^10 - 1.

2. Step 2: Calculate maximum value

   2^10 - 1 = 1024 - 1 = 1023.

3. Final Answer:

   1023 -> Option A

4. Quick Check:

   10-bit ADC max = 1023 [OK]

Hint: 10-bit ADC max value is 2^10 minus 1 = 1023 [OK]

Common Mistakes:

• Confusing 10-bit with 8-bit max value (255)
• Using 512 which is half range
• Using 4095 which is 12-bit max

2. Which of the following is the correct syntax to read an analog value from pin A0 in Arduino?

easy

A. readAnalog(A0);

B. digitalRead(A0);

C. analogReadPin(A0);

D. analogRead(A0);

Solution

1. Step 1: Recall Arduino analog read syntax

   The function to read analog input is analogRead(pin).

2. Step 2: Identify correct pin notation

   Pin A0 is correctly passed as A0, not using digitalRead or other variants.

3. Final Answer:

   analogRead(A0); -> Option D

4. Quick Check:

   Correct function and pin name used [OK]

Hint: Use analogRead() with A0 for analog pin 0 [OK]

Common Mistakes:

• Using digitalRead(A0) which reads digital value (0 or 1)
• Using non-existent functions like analogReadPin()
• Using readAnalog() which is not Arduino syntax

3. Given the code:

int sensorValue = analogRead(A1);
float voltage = sensorValue * (5.0 / 1023.0);
Serial.println(voltage);

If analogRead(A1) returns 512, what will be printed?

medium

A. 1.0

B. 5.0

C. 2.5

D. 0.5

Solution

1. Step 1: Substitute sensorValue with 512

   voltage = 512 * (5.0 / 1023.0)

2. Step 2: Calculate voltage value

   5.0 / 1023.0 ≈ 0.004887585, so voltage ≈ 512 * 0.004887585 ≈ 2.5

3. Final Answer:

   2.5 -> Option C

4. Quick Check:

   Half of 5V ≈ 2.5V for 512 reading [OK]

Hint: Multiply reading by 5/1023 to get voltage [OK]

Common Mistakes:

• Using 1024 instead of 1023 in division
• Confusing sensorValue with voltage directly
• Rounding errors ignoring decimal precision

4. What is wrong with this Arduino code snippet?

int sensorValue = analogRead(A2);
float voltage = sensorValue * (5 / 1023);
Serial.println(voltage);

medium

A. Division uses integer math, causing voltage to be zero

B. analogRead() cannot read from A2

C. Serial.println() cannot print float values

D. sensorValue should be float, not int

Solution

1. Step 1: Analyze division in voltage calculation

   5 / 1023 uses integer division, which results in 0.

2. Step 2: Effect on voltage value

   Multiplying sensorValue by 0 gives voltage = 0 always.

3. Final Answer:

   Division uses integer math, causing voltage to be zero -> Option A

4. Quick Check:

   Use float division 5.0/1023.0 to fix [OK]

Hint: Use decimal points for float division (5.0/1023.0) [OK]

Common Mistakes:

• Ignoring integer division effect
• Thinking analogRead can't read A2
• Believing Serial.println can't print floats

5. You want to measure a sensor voltage that ranges from 0 to 3.3V using Arduino's 10-bit ADC with 5V reference. Which formula correctly converts the ADC reading to the sensor voltage?

hard

A. voltage = reading * (3.3 / 1023.0);

B. voltage = reading * (5.0 / 1023.0);

C. voltage = reading * (3.3 / 1024.0);

D. voltage = reading * (5.0 / 1024.0);

Solution

1. Step 1: Understand ADC reference voltage

   The ADC measures voltage from 0 to 5V (reference voltage).

2. Step 2: Calculate voltage from ADC reading

   Since ADC max is 1023, voltage = reading * (5.0 / 1023.0).

3. Step 3: Sensor voltage range consideration

   The sensor outputs 0-3.3V, but Arduino reads 0-5V range, so conversion uses 5V scale.

4. Final Answer:

   voltage = reading * (5.0 / 1023.0); -> Option B

5. Quick Check:

   Use ADC reference voltage (5V) for conversion [OK]

Hint: Always scale by ADC reference voltage, not sensor max voltage [OK]

Common Mistakes:

• Using sensor max voltage instead of ADC reference
• Using 1024 instead of 1023 in denominator
• Confusing sensor output range with ADC range