Servo angle positioning in Arduino - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to include the Servo library.

Arduino

#include [1]

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

A<Servo.h>

B<Servo>

C"Servo.h"

D<servo.h>

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes instead of angle brackets

Misspelling the library name

Using lowercase letters in the filename

The Servo library is included with #include <Servo.h> to control servo motors.

2fill in blank

medium

Complete the code to attach the servo to pin 9.

Arduino

servo.[1](9);

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

Aconnect

Bstart

Cbegin

Dattach

Attempts:

3 left

💡 Hint

Common Mistakes

Using connect() instead of attach()

Using begin() or start() which are not servo methods

The attach() method connects the servo object to the specified pin.

3fill in blank

hard

Fix the error in the code to write 90 degrees to the servo.

Arduino

servo.[1](90);

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

AwriteAngle

Bwrite

CsetAngle

Dmove

Attempts:

3 left

💡 Hint

Common Mistakes

Using writeAngle() or setAngle() which do not exist

Using move() which is not a Servo method

The correct method to set the servo angle is write().

4fill in blank

hard

Fill both blanks to create a loop that moves the servo from 0 to 180 degrees in steps of 30.

Arduino

for (int angle = [1]; angle <= [2]; angle += 30) {
  servo.write(angle);
  delay(500);
}

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

A0

B180

C90

D360

Attempts:

3 left

💡 Hint

Common Mistakes

Using 90 as start or end angle

Using 360 which is beyond servo range

The loop starts at 0 degrees and goes up to 180 degrees to cover the servo's range.

5fill in blank

hard

Fill all three blanks to create a dictionary-like mapping of angles to delay times and move the servo only if delay is greater than 300 ms.

Arduino

int delays[] = {100, 400, 600};
for (int i = 0; i < 3; i++) {
  int angle = [1];
  int delayTime = delays[i];
  if (delayTime [2] 300) {
    servo.[3](angle);
    delay(delayTime);
  }
}

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

Ai * 60

B>

Cwrite

Di + 30

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' instead of '*' for angle calculation

Using '<' instead of '>' in the if condition

Using move() instead of write() for servo

We calculate angle as i*60, check if delayTime > 300, and use write() to move the servo.

Practice

1. What does the Servo.write(angle) function do in Arduino servo control?

easy

A. Reads the current angle of the servo motor

B. Sets the servo motor to the specified angle between 0 and 180 degrees

C. Attaches the servo motor to a pin

D. Stops the servo motor immediately

Solution

1. Step 1: Understand Servo.write() purpose

   The Servo.write(angle) function commands the servo to move to the angle given as a parameter, which must be between 0 and 180 degrees.

2. Step 2: Differentiate from other functions

   Servo.attach() connects the servo to a pin, Servo.read() reads the current angle, and stopping is not done by Servo.write().

3. Final Answer:

   Sets the servo motor to the specified angle between 0 and 180 degrees -> Option B

4. Quick Check:

   Servo.write(angle) sets angle [OK]

Hint: Servo.write sets angle; attach connects servo [OK]

Common Mistakes:

• Confusing Servo.write() with Servo.attach()
• Thinking Servo.write() reads angle
• Assuming Servo.write() stops the servo

2. Which of the following is the correct way to attach a servo to pin 9 in Arduino?

easy

A. servo.connect(9);

B. servo.attachPin(9);

C. servo.attach(9);

D. servo.setPin(9);

Solution

1. Step 1: Recall correct Servo library syntax

   The correct method to connect a servo to a pin is servo.attach(pinNumber); where pinNumber is the Arduino pin number.

2. Step 2: Verify other options

   Methods like attachPin(), connect(), or setPin() do not exist in the Servo library.

3. Final Answer:

   servo.attach(9); -> Option C

4. Quick Check:

   servo.attach(pin) attaches servo [OK]

Hint: Use attach() to connect servo to pin [OK]

Common Mistakes:

• Using non-existent methods like attachPin()
• Confusing attach() with write()
• Forgetting parentheses in attach()

3. What will be the servo angle after running this code snippet?

#include <Servo.h>
Servo servo;
void setup() {
  servo.attach(10);
  servo.write(90);
  delay(1000);
  servo.write(45);
}
void loop() {}

medium

A. 45 degrees

B. 90 degrees

C. 135 degrees

D. 0 degrees

Solution

1. Step 1: Analyze servo.write() calls in setup()

   The servo is first set to 90 degrees, then after 1 second delay, it is set to 45 degrees.

2. Step 2: Determine final servo position after setup()

   The last command in setup() sets the servo to 45 degrees, so it stays there since loop() is empty.

3. Final Answer:

   45 degrees -> Option A

4. Quick Check:

   Last servo.write() angle = 45 [OK]

Hint: Last servo.write() sets final angle [OK]

Common Mistakes:

• Ignoring the second servo.write() call
• Assuming delay changes angle
• Thinking loop() affects angle here

4. Identify the error in this Arduino code controlling a servo:

#include <Servo.h>
Servo myServo;
void setup() {
  myServo.attach(5);
  myServo.write(200);
}
void loop() {}

medium

A. Servo angle 200 is out of valid range (0-180)

B. Servo not attached to pin 5 correctly

C. Missing delay after write()

D. Servo library not included

Solution

1. Step 1: Check servo angle range

   The servo angle must be between 0 and 180 degrees. Writing 200 is invalid and may cause unexpected behavior.

2. Step 2: Verify other code parts

   The servo is attached correctly to pin 5, delay is optional but recommended, and the Servo library is included.

3. Final Answer:

   Servo angle 200 is out of valid range (0-180) -> Option A

4. Quick Check:

   Servo angle must be 0-180 [OK]

Hint: Servo angles must be 0 to 180 degrees [OK]

Common Mistakes:

• Setting angle above 180
• Ignoring servo angle limits
• Assuming delay is mandatory

5. You want to sweep a servo smoothly from 0 to 180 degrees and back continuously. Which code snippet correctly implements this behavior?

hard

A. servo.write(0); delay(1000); servo.write(180); delay(1000);

B. servo.attach(9); servo.write(90);

C. while(true) { servo.write(90); delay(1000); }

D. for(int angle=0; angle<=180; angle++) { servo.write(angle); delay(15); } for(int angle=180; angle>=0; angle--) { servo.write(angle); delay(15); }

Solution

1. Step 1: Understand sweeping motion requirements

   Sweeping means moving the servo gradually from 0 to 180 degrees and back repeatedly, requiring loops and small delays for smooth movement.

2. Step 2: Analyze each option

   for(int angle=0; angle<=180; angle++) { servo.write(angle); delay(15); } for(int angle=180; angle>=0; angle--) { servo.write(angle); delay(15); } uses two for loops to increment and decrement angle with delays, creating smooth sweep. servo.write(0); delay(1000); servo.write(180); delay(1000); jumps instantly between 0 and 180. while(true) { servo.write(90); delay(1000); } holds at 90 degrees. servo.attach(9); servo.write(90); only sets servo once.

3. Final Answer:

   for(int angle=0; angle<=180; angle++) { servo.write(angle); delay(15); } for(int angle=180; angle>=0; angle--) { servo.write(angle); delay(15); } -> Option D

4. Quick Check:

   Sweep needs gradual angle changes with delay [OK]

Hint: Use loops with delay for smooth servo sweep [OK]

Common Mistakes:

• Jumping angles without gradual steps
• Missing delay causing jerky movement
• Not looping back from 180 to 0