Servo angle positioning in Arduino - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a servo motor in Arduino projects?

A servo motor is a small device that can move to a specific angle when told by the Arduino. It is used to control precise movements like turning a wheel or moving a robot arm.

beginner

How do you include the Servo library in an Arduino sketch?

You include the Servo library by writing #include <Servo.h> at the top of your Arduino code. This lets you use servo functions easily.

beginner

What function moves the servo to a specific angle?

The function servo.write(angle); moves the servo to the angle you specify, where angle is between 0 and 180 degrees.

beginner

Why do you need to attach a servo to a pin in Arduino?

You attach a servo to a pin using servo.attach(pinNumber); so the Arduino knows which pin controls the servo motor.

beginner

What is the typical angle range for a standard servo motor?

Most standard servo motors move between 0 and 180 degrees. This means you can tell the servo to point anywhere in that range.

Which Arduino library is used to control servo motors?

A SPI

B Wire

C EEPROM

D Servo

The Servo library is specifically designed to control servo motors in Arduino.

What does servo.write(90); do?

A Moves the servo to 90 degrees

B Moves the servo to 0 degrees

C Stops the servo

D Moves the servo to 180 degrees

The write function moves the servo to the angle given, here 90 degrees.

Before moving a servo, what must you do in your code?

A Set pinMode to OUTPUT

B Attach the servo to a pin

C Start Serial communication

D Declare a variable

You must attach the servo to a pin using servo.attach(pinNumber); before controlling it.

What is the valid angle range for most servo motors?

A 0 to 90 degrees

B 0 to 360 degrees

C 0 to 180 degrees

D -90 to 90 degrees

Standard servos usually move between 0 and 180 degrees.

Which pin type should you connect a servo signal wire to on Arduino?

A Digital PWM pin

B Analog input pin

C Power pin

D Ground pin

Servo signal wires connect to digital PWM pins to receive control signals.

Explain how to control a servo motor angle using Arduino code.

Think about the steps from setup to moving the servo.

What are the typical angle limits of a servo motor and why is it important to stay within them?

Consider what happens if you try to move beyond the servo's range.

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