Arduino Uno Servo Motor | How Do Servo Motors Work?

Step 3: How It Works

Servos are clever devices. Using just one input pin, they receive the position from the Arduino and they go there. Internally, they have a motor driver and a feedback circuit that makes sure that the servo arm reaches the desired position. But what kind of signal do they receive on the input pin?

It is a square wave similar to PWM. Each cycle in the signal lasts for 20 milliseconds and for most of the time, the value is LOW. At the beginning of each cycle, the signal is HIGH for a time between 1 and 2 milliseconds. At 1 millisecond it represents 0 degrees and at 2 milliseconds it represents 180 degrees. In between, it represents the value from 0–180. This is a very good and reliable method. The graphic makes it a little easier to understand.

Remember that using the Servo library automatically disables PWM functionality on PWM pins 9 and 10 on the Arduino UNO and similar boards.

Code breakdown

The code simply declares the servo object and then initializes the servo by using the servo.attach() function. We shouldn’t forget to include the servo library. In the loop(), we set the servo to 0 degrees, wait, then set it to 90, and later to 180 degrees.

Testing it out

After we have successfully uploaded the code to the board, the standard servo should now start moving from 0 – 180, and then start moving from 180 – 0. This is due to the two for loops in the program, which gradually increases the

variable, which is written to the servo.

pos


Congratulations! That was just a few easy steps to get started with standard servo motors. Now that you have this working, you can start exploring a lot of different cool projects that uses servo motors, and perhaps start making your very own robot!

Step 4: More Things About Servos

Controlling servos is easy, and here are a few more tricks we can use:

Controlling the exact pulse time

Arduino has a built-in function servo.write(degrees) that simplifies the control of servos. However, not all servos respect the same timings for all positions. Usually, 1 millisecond means 0 degrees, 1.5 milliseconds mean 90 degrees, and, of course, 2 milliseconds mean 180 degrees. Some servos have smaller or larger ranges.

For better control, we can use the servo.writeMicroseconds(us) function, which takes the exact number of microseconds as a parameter. Remember, 1 millisecond equals 1,000 microseconds.

More servos

In order to use more than one servo, we need to declare multiple servo objects, attach different pins to each one, and address each servo individually. First, we need to declare the servo objects—as many as we need:

// Create servo objects Servo Servo1, Servo2, Servo3;

Then we need to attach each object to one servo motor. Remember, every servo motor uses an individual pin:

Servo1.attach(servoPin1); Servo2.attach(servoPin2); Servo3.attach(servoPin3);

In the end, we just have to address each servo object individually:

Servo1.write(0); // Set Servo 1 to 0 degrees Servo2.write(90); // Set Servo 2 to 90 degrees

Connection-wise, the grounds from the servos go to GND on the Arduino, the servo power to 5V or VIN (depending on the power input), and in the end, each signal line has to be connected to a different digital pin. Contrary to popular belief, servos don’t need to be controlled by PWM pins—any digital pin will work.

Continuous rotation servos

There is a special breed of servos labelled as continuous rotation servos. While a normal servo goes to a specific position depending on the input signal, a continuous rotation servo either rotates clockwise or counter-clockwise at a speed proportional to the signal. For example, the Servo1.write(0) function will make the servomotor spin counter-clockwise at full speed. The Servo1.write(90) function will stop the motor and Servo1.write(180) will turn the motor clockwise at full speed.

There are multiple uses for such servos; however, they are really slow. If you are building a microwave and need a motor to turn the food, this is your choice. But be careful, microwaves are dangerous!

How Do Servo Motors Work?

You can control the servo motor by sending a series of pulses to it. A typical servo motor expects a pulse every 20 milliseconds (i.e., the signal should be 50Hz).

The length of the pulse determines the position of the servo motor.

• A short pulse of 1 ms or less will rotate the servo to 0 degrees (one extreme).
• A pulse duration of 1.5 ms will rotate the servo to 90 degrees (middle position).
• A pulse duration of 2 ms or so will rotate the servo to 180 degrees (other extreme).

Pulses ranging from 1ms to 2ms will rotate the servo to a position proportional to the pulse width. The animation below will help you understand the relationship between pulses and position.

It is important to note that there is no standard for the exact relationship between pulses and position, so you may need to tweak your sketch to adjust for the range of your servo.

Also, the pulse duration can vary between brands; for example, it might be 2.5ms for 180 degrees and 0.5ms for 0 degrees.

Popular RC / Hobby Servos for Arduino Projects

There are many different models and manufacturers of RC or hobby. The main consideration when choosing a servo motor is its torque, operating voltage, current draw and size.

Here are the two most popular servo models among makers, the SG90 Micro Servo and the MG996R.

SG90 Micro Servo technical specifications:

Stall Torque	1.2kg·cm @4.8V, 1.6kg·cm @6V,
Operating Voltage	3.5 – 6V
No Load Current	100mA
Stall Current	650mA
Max Speed	60 degrees in 0.12s
Weight	9g

MG996R Servo technical specifications:

Stall Torque	11kg.cm @4.8v, 13kg.cm @6V
Operating Voltage	4.8 – 7.2V
No Load Current	220mA @4.8V, 250mA @6V
Stall Current	650mA
Max Speed	60 degrees in 0.20s
Weight	55g

Step 1: How to Connect Them

A servo motor has everything built in: a motor, a feedback circuit, and most important, a motor driver. It just needs one power line, one ground, and one control pin.

Following are the steps to connect a servo motor to the Arduino:

1. The servo motor has a female connector with three pins. The darkest or even black one is usually the ground. Connect this to the Arduino GND.
2. Connect the power cable that in all standards should be red to 5V on the Arduino.
3. Connect the remaining line on the servo connector to a digital pin on the Arduino.

Check the image for a view of the servo connected to the Arduino.

Powering Servo Motors

Servo motors have different power requirements depending on their size and the workload they are experiencing. A common servo motor such as the Feetech Mini Servo Motor requires between 4.8 – 6 V at 5 – 6 mA when idle. It doesn’t take very much energy to stand still.

But as soon as the motor starts moving, it starts using more energy, and it gets that energy by pulling more current from the power source.

If it experiences heavier loads such as added weight or an object blocking its movement , it naturally needs to use even more energy to move the obstacle, and as a result the current consumption increases. The current consumption of the motor linked above can reach up to 800 mA.

This high current-draw is generally not safe to draw from an Arduino board. To avoid damaging our board we need to power the servo motor through an external power supply. Choosing the correct power supply depends on the servo motor you are using, so always check the specifications. Pay especially close attention to the:

• operating voltage range
• idle current – consumption when not moving
• running current – consumption when moving freely
• stall current – consumption under max load or when blocked

To power a 4.8 – 6 V servo you could use a 5 V 1 A AC Adapter, cut the cable, and connect the wires to the servo using e.g. a breadboard.

Note that USB wall chargers are limited to 500 mA (USB 2.0) or 900 mA (USB 3.0).

If your project needs to move around freely without being attached to a power outlet you can also choose batteries to power the servo. If you need 5 V exactly you can use two 18650 Li-Ion batteries together with a step-down converter.

A step-down converter is needed because 18650 Li-Ion batteries will give you around 7.4 V. The max current depends on the specific battery but most of them are designed to output above 1A which is enough to power our small servo.

If you are using bigger or more servos make sure to check your power requirements accordingly.

Capacitors are recommended for powering servo motors. They help stabilize the power supply, minimize voltage drops, and reduce electrical noise. The specific capacitor values may vary based on the servo motor’s requirements, but including them is good practice for better performance and reliability.

When using a Feetech Mini Servo Motor we recommend using a 100 µF capacitor.

Because some capacitors are polarised (meaning that they have a direction), you may need to be careful with how you connect them to your circuit. Make sure to connect them correctly by checking for markings such as a white stripe, a ‘+’ symbol, or a longer lead. If your capacitor has these, match the indicators of the capacitor with your circuit (pay attention to the + and – signs), and be careful not to exceed the voltage limits. This precaution helps prevent issues like leaks or damage that could harm your circuit.

You can read more about capacitors here.

Step 4: More Things About Servos

Controlling servos is easy, and here are a few more tricks we can use:

Controlling the exact pulse time

Arduino has a built-in function servo.write(degrees) that simplifies the control of servos. However, not all servos respect the same timings for all positions. Usually, 1 millisecond means 0 degrees, 1.5 milliseconds mean 90 degrees, and, of course, 2 milliseconds mean 180 degrees. Some servos have smaller or larger ranges.

For better control, we can use the servo.writeMicroseconds(us) function, which takes the exact number of microseconds as a parameter. Remember, 1 millisecond equals 1,000 microseconds.

More servos

In order to use more than one servo, we need to declare multiple servo objects, attach different pins to each one, and address each servo individually. First, we need to declare the servo objects—as many as we need:

// Create servo objects Servo Servo1, Servo2, Servo3;

Then we need to attach each object to one servo motor. Remember, every servo motor uses an individual pin:

Servo1.attach(servoPin1); Servo2.attach(servoPin2); Servo3.attach(servoPin3);

In the end, we just have to address each servo object individually:

Servo1.write(0); // Set Servo 1 to 0 degrees Servo2.write(90); // Set Servo 2 to 90 degrees

Connection-wise, the grounds from the servos go to GND on the Arduino, the servo power to 5V or VIN (depending on the power input), and in the end, each signal line has to be connected to a different digital pin. Contrary to popular belief, servos don’t need to be controlled by PWM pins—any digital pin will work.

Continuous rotation servos

There is a special breed of servos labelled as continuous rotation servos. While a normal servo goes to a specific position depending on the input signal, a continuous rotation servo either rotates clockwise or counter-clockwise at a speed proportional to the signal. For example, the Servo1.write(0) function will make the servomotor spin counter-clockwise at full speed. The Servo1.write(90) function will stop the motor and Servo1.write(180) will turn the motor clockwise at full speed.

There are multiple uses for such servos; however, they are really slow. If you are building a microwave and need a motor to turn the food, this is your choice. But be careful, microwaves are dangerous!

Servo Motor Control Arduino Code

Now let’s take a look at the Arduino code for controlling the servo motor. The code is very simple. We just need to define the pin to which the servo is connect, define that pin as an output, and in the loop section generate pulses with the specific duration and frequency as we explained earlier.


/* Servo Motor Control - 50Hz Pulse Train Generator by Dejan, https://howtomechatronics.com */ void setup() { pinMode(servoPin, OUTPUT); } void loop() { // A pulse each 20ms digitalWrite(servoPin, HIGH); delayMicroseconds(1450); // Duration of the pusle in microseconds digitalWrite(servoPin, LOW); delayMicroseconds(18550); // 20ms - duration of the pusle // Pulses duration: 600 - 0deg; 1450 - 90deg; 2300 - 180deg }

Code language: Arduino (arduino)

After some testing I came up with the following values for the duration of the pulses that work with my servo. Pulses with 0.6ms duration corresponded to 0 degrees position, 1.45ms to 90 degrees and 2.3ms to 180 degrees.

I connected a multimeter in series with the servo to check the current draw. The maximum current draw that I noticed was up to 0.63A at stall. Well that’s because this isn’t the original TowerPro MG996R servo, but a cheaper replica, which obviously has worse performance.

Nevertheless, let’s take a look at a more convenient way of controlling servos using Arduino. That’s using the Arduino servo library.


/* Servo Motor Control using the Arduino Servo Library by Dejan, https://howtomechatronics.com */ Servo myservo; // create servo object to control a servo void setup() { myservo.attach(9,600,2300); // (pin, min, max) } void loop() { myservo.write(0); // tell servo to go to a particular angle delay(1000); myservo.write(90); delay(500); myservo.write(135); delay(500); myservo.write(180); delay(1500); }

Code language: Arduino (arduino)

Here we just need to include the library, define the servo object, and using the attach() function define the pin to which the servo is connected as well as define the minimum and maximum values of the pulses durations. Then using the write() function we simply set the position of the servo from 0 to 180 degrees.

Step 5: Check Out More

More topics regarding motors such as brushless, transistor drivers ormotor speed control can be found in my Arduino Development Cookbook available here. 😀

Usage

This library allows an Arduino board to control RC (hobby) servo motors. Servos have integrated gears and a shaft that can be precisely controlled. Standard servos allow the shaft to be positioned at various angles, usually between 0 and 180 degrees. Continuous rotation servos allow the rotation of the shaft to be set to various speeds.

The Servo library supports up to 12 motors on most Arduino boards and 48 on the Arduino Mega. On boards other than the Mega, use of the library disables

analogWrite()

(PWM) functionality on pins 9 and 10, whether or not there is a Servo on those pins. On the Mega, up to 12 servos can be used without interfering with PWM functionality; use of 12 to 23 motors will disable PWM on pins 11 and 12.

To use this library:


#include


Circuit

Servo motors have three wires: power, ground, and signal. The power wire is typically red, and should be connected to the 5V pin on the Arduino board. The ground wire is typically black or brown and should be connected to a ground pin on the Arduino board. The signal pin is typically yellow, orange or white and should be connected to a digital pin on the Arduino board. Note that servos draw considerable power, so if you need to drive more than one or two, you’ll probably need to power them from a separate supply (i.e. not the 5V pin on your Arduino). Be sure to connect the grounds of the Arduino and external power supply together.

Usage

This library allows an Arduino board to control RC (hobby) servo motors. Servos have integrated gears and a shaft that can be precisely controlled. Standard servos allow the shaft to be positioned at various angles, usually between 0 and 180 degrees. Continuous rotation servos allow the rotation of the shaft to be set to various speeds.

The Servo library supports up to 12 motors on most Arduino boards and 48 on the Arduino Mega. On boards other than the Mega, use of the library disables

analogWrite()

(PWM) functionality on pins 9 and 10, whether or not there is a Servo on those pins. On the Mega, up to 12 servos can be used without interfering with PWM functionality; use of 12 to 23 motors will disable PWM on pins 11 and 12.

To use this library:


#include


Circuit

Servo motors have three wires: power, ground, and signal. The power wire is typically red, and should be connected to the 5V pin on the Arduino board. The ground wire is typically black or brown and should be connected to a ground pin on the Arduino board. The signal pin is typically yellow, orange or white and should be connected to a digital pin on the Arduino board. Note that servos draw considerable power, so if you need to drive more than one or two, you’ll probably need to power them from a separate supply (i.e. not the 5V pin on your Arduino). Be sure to connect the grounds of the Arduino and external power supply together.

There are many motors to pick from, but it’s important to pick the right one for the job. If your project requires precise positioning, a servo motor is usually the best option. Instruct them where to point, and they’ll do it for you. It’s as simple as that!

They’re useful in a variety of robotics projects, such as steering an RC model’s front wheels or pivoting a sensor on a robotic vehicle.

Troubleshooting

Sometimes, your servo may misbehave, especially if you decide to operate it directly from the Arduino. The reason for this is that the servo consumes a significant amount of power, particularly during startup, which can cause the Arduino board to reset.

To solve this problem, place a relatively large electrolytic decoupling capacitor (470µF – 1000µF) across the input power. Make sure the capacitor’s longer lead is connected to 5V and the negative lead is connected to GND.

The capacitor stores electric charge, so when the motor starts, it draws power from both the Arduino supply and the capacitor, ensuring a smooth flow of current.

Powering Servo Motors

Servo motors have different power requirements depending on their size and the workload they are experiencing. A common servo motor such as the Feetech Mini Servo Motor requires between 4.8 – 6 V at 5 – 6 mA when idle. It doesn’t take very much energy to stand still.

But as soon as the motor starts moving, it starts using more energy, and it gets that energy by pulling more current from the power source.

If it experiences heavier loads such as added weight or an object blocking its movement , it naturally needs to use even more energy to move the obstacle, and as a result the current consumption increases. The current consumption of the motor linked above can reach up to 800 mA.

This high current-draw is generally not safe to draw from an Arduino board. To avoid damaging our board we need to power the servo motor through an external power supply. Choosing the correct power supply depends on the servo motor you are using, so always check the specifications. Pay especially close attention to the:

• operating voltage range
• idle current – consumption when not moving
• running current – consumption when moving freely
• stall current – consumption under max load or when blocked

To power a 4.8 – 6 V servo you could use a 5 V 1 A AC Adapter, cut the cable, and connect the wires to the servo using e.g. a breadboard.

Note that USB wall chargers are limited to 500 mA (USB 2.0) or 900 mA (USB 3.0).

If your project needs to move around freely without being attached to a power outlet you can also choose batteries to power the servo. If you need 5 V exactly you can use two 18650 Li-Ion batteries together with a step-down converter.

A step-down converter is needed because 18650 Li-Ion batteries will give you around 7.4 V. The max current depends on the specific battery but most of them are designed to output above 1A which is enough to power our small servo.

If you are using bigger or more servos make sure to check your power requirements accordingly.

Capacitors are recommended for powering servo motors. They help stabilize the power supply, minimize voltage drops, and reduce electrical noise. The specific capacitor values may vary based on the servo motor’s requirements, but including them is good practice for better performance and reliability.

When using a Feetech Mini Servo Motor we recommend using a 100 µF capacitor.

Because some capacitors are polarised (meaning that they have a direction), you may need to be careful with how you connect them to your circuit. Make sure to connect them correctly by checking for markings such as a white stripe, a ‘+’ symbol, or a longer lead. If your capacitor has these, match the indicators of the capacitor with your circuit (pay attention to the + and – signs), and be careful not to exceed the voltage limits. This precaution helps prevent issues like leaks or damage that could harm your circuit.

You can read more about capacitors here.

Arduino Example 1 – Sweep

To get started, we will use one of the Arduino IDE’s built-in examples. Navigate to the Examples sub-menu. Select the Servo and load the Sweep sketch.

Go ahead and upload the sketch. The shaft of your servo motor will begin to sweep back and forth across 180 degrees.


#include

int servoPin = 9; Servo servo; int angle = 0; // servo position in degrees void setup() { servo.attach(servoPin); } void loop() { // scan from 0 to 180 degrees for(angle = 0; angle < 180; angle++) { servo.write(angle); delay(15); } // now scan back from 180 to 0 degrees for(angle = 180; angle > 0; angle--) { servo.write(angle); delay(15); } }



Code Explanation:

Controlling servos is not a simple task, but fortunately, the Arduino IDE already includes a wonderful library called Servo. It contains simple commands that can be used to quickly instruct the servo to rotate to a specific angle.

Therefore, at the beginning of the sketch, we include this library.


#include


Then we declare the Arduino pin to which the servo motor’s control pin is connected.


int servoPin = 9;


The line below creates a servo object.


Servo servo;


You can actually define up to eight servos in this way; for example, if you had two servos, you would write:


Servo servo1; Servo servo2;


The variable

angle

is used to store the servo’s current angle in degrees.


int angle = 0;


In the setup function, we use the following command to link the

servo

object to the control pin of our servo:


servo.attach(servoPin);


The loop function has two

for

loops. The first loop will rotate the motor in one direction, while the second will rotate it in the opposite direction.

The

servo.write(angle)

function instructs the servo to update its position to the specified angle.


servo.write(angle);


Sơ đồ đấu nối

Arduino Uno	Động cơ Servo SG90
5V	Dây màu đỏ
GND	Dây màu đen
D9	Dây màu vàng

Các linh kiện cần thiết cho dự án

TÊN LINH KIỆN	SỐ LƯỢNG	NƠI BÁN
Arduino Uno R3	Shopee | Cytron
Động cơ Servo SG90	Shopee | Cytron
Dây cắm	10-20	Shopee | Cytron
Breadboard	Shopee | Cytron

Controlling Multiple Servo Motors with Arduino

The Arduino servo library supports controlling of up to 12 servos at the same time with most the Arduino boards, and 48 servos using the Arduino Mega board. On top of that, controlling multiple servo motors with Arduino is as easy as controlling just a single one.

Here’s an example code for controlling multiple servos:


/* Controlling multiple servo motors with Arduino by Dejan, https://howtomechatronics.com */ Servo servo1; Servo servo2; Servo servo3; Servo servo4; Servo servo5; void setup() { servo1.attach(8); servo2.attach(9); servo3.attach(10); servo4.attach(11); servo5.attach(12); } void loop() { // move all servos to position 0 servo1.write(0); servo2.write(0); servo3.write(0); servo4.write(0); servo5.write(0); delay(2000); // move all servos to position 90 servo1.write(90); servo2.write(90); servo3.write(90); servo4.write(90); servo5.write(90); delay(2000); // move all servos to position 180 servo1.write(180); servo2.write(180); servo3.write(180); servo4.write(180); servo5.write(180); delay(2000); }

Code language: Arduino (arduino)

So, we just have to create objects from the Servo class for each servo motor, and define to which Arduino pin is connected. Of course, we can set any servo to move to any position, at any time.

As an example you can also check my Arduino Ant Hexapod Robot project where I used an Arduino MEGA board to control 22 servo motors.

Troubleshooting

Servo motor jitters and resets my Arduino board

This is a common problem with these hobby servo motors, the SG90 Micro Servo and the MG996R. The reason for this is that, as mentioned earlier, they can draw quite significant amount of current when they are at load. This can cause the Arduino board to reset, especially if you are powering the servo directly from the Arduino 5V pin.

In order to solve this issue you can use a capacitor across the GND and the 5V pin. It will act as a decouple capacitor which will provide additional current to the system at start up when the DC motor starts.

Servo motor won’t move entire range from 0 to 180 degrees

This is another common problem with these hobby servos. As we explained earlier, a pulse width of 1ms (0.5ms) corresponds to 0 degrees position, and 2ms (2.5ms) to 180 degrees. However, these values can vary from servo to servo and between different manufacturers.

In order to solve this problem, we need to adjust the pulse width we are sending to the servo motor with the Arduino. Luckily, using the Arduino Servo library we can easily adjust the pulse widths values in the attach() function.

The attach() function can take two additional parameters, and that’s the minimum and maximum pulse width in microseconds. The default values are 544 microseconds (0.544milliseconds) for minimum (0 degrees) angle, and 2400 microseconds (2.4ms). So by adjusting these values we can fine tune the moment range of the servo.


myservo.attach(9,600,2300); // (pin, min, max)

Code language: Arduino (arduino)

Conclusion

Congratulations! That was just a few easy steps to get started with standard servo motors. Now that you have this working, you can start exploring a lot of different cool projects that uses servo motors, and perhaps start making your very own robot!

Feel free to explore the Servo further.

Suggested changes

The content on docs.arduino.cc is facilitated through a public GitHub repository. You can read more on how to contribute in the contribution policy.

License

The Arduino documentation is licensed under the Creative Commons Attribution-Share Alike 4.0 license.

Dimensions and 3D Model

I made 3D models of the two most popular servo motors, the SG90 Micro Servo and the MG996R servo motor. You can download load them from the links below.

SG90 Micro Servo

3D Model: Download from Thangs.

Dimensions:

MG996R Servo Motor

MG996R Servo Motor 3D Model: Download from Thangs.

Dimensions:

Circuit

Servo motors have three wires: power, ground, and signal. The power wire is typically red, and should be connected to positive pole (+) of your power source. The ground wire is typically black or brown and should be connected to the negative pole (-) of your power source.

The signal pin is typically yellow or orange and should be connected to PWM pin on the board. In these examples, it is pin number 9.

Knob Circuit

For the Knob example, wire the potentiometer so that its two outer pins are connected to power (+5V) and ground, and its middle pin is connected to

on the board. Then, connect the servo motor as shown in the circuit below.

A0


Sweep Circuit

For the Sweep example, connect the servo motor as shown in the circuit below.

Arduino Servo Motor Control

Let’s put the above said to test and make a practical example of controlling a hobby servo using Arduino. I will use the MG996R which is a high-torque servo featuring metal gearing with stall torque of 10 kg-cm. The high torque comes at a price and that’s the stall current of the servo which is 2.5A. The running current is from 500mA to 900mA and the operating voltage is from 4.8 to 7.2V.

The current ratings indicate that we cannot directly connect this servo to the Arduino, but we must use a separate power supply for it.

Circuit Diagram

Here’s the circuit diagram for this example.

We simply need to connect the control pin of the servo to any digital pin of the Arduino board, connect the Ground and the positive wires to the external 5V power supply, and also connect the Arduino ground to the servo ground.

In case we use a smaller hobby servo, the S90 Micro Servo, it’s possible to power it directly from the 5V Arduino pin.

The S90 Micro Servo has lower current consumption, around 100-200mA no-load running current, but around 500-700mA stall current. On the other hand, the Arduino 5V pin can output only around 500mA if powered via USB, or up to 1A in powered via the barrel connector.

Even though it’s possible to run these 9g servo motors directly to Arduino, for more stable work I would suggest to always use an external power supply for them.

You can get the components needed for this example from the links below:

• MG996R Servo Motor …………………………. Amazon / Banggood / AliExpress
• or S90 Micro Servo ………..…………………… Amazon / Banggood / AliExpress
• Arduino Board ……………………………………. Amazon / Banggood / AliExpress
• 5V 2A DC Power Supply …………………..….. Amazon / Banggood / AliExpress

Disclosure: These are affiliate links. As an Amazon Associate I earn from qualifying purchases.

Examples

Knob

Controlling a servo position using a potentiometer (variable resistor).

1#include

23Servo myservo; // create servo object to control a servo45int potpin = 0; // analog pin used to connect the potentiometer6int val; // variable to read the value from the analog pin78void setup() {9 myservo.attach(9); // attaches the servo on pin 9 to the servo object10}1112void loop() {13 val = analogRead(potpin); // reads the value of the potentiometer (value between 0 and 1023)14 val = map(val, 0, 1023, 0, 180); // scale it to use it with the servo (value between 0 and 180)15 myservo.write(val); // sets the servo position according to the scaled value16 delay(15); // waits for the servo to get there17}

Sweep

Sweeps the shaft of a RC servo motor back and forth across 180 degrees.

1#include

23Servo myservo; // create servo object to control a servo4// twelve servo objects can be created on most boards56int pos = 0; // variable to store the servo position78void setup() {9 myservo.attach(9); // attaches the servo on pin 9 to the servo object10}1112void loop() {13 for (pos = 0; pos <= 180; pos += 1) { // goes from 0 degrees to 180 degrees14 // in steps of 1 degree15 myservo.write(pos); // tell servo to go to position in variable ‘pos’16 delay(15); // waits 15ms for the servo to reach the position17 }18 for (pos = 180; pos >= 0; pos -= 1) { // goes from 180 degrees to 0 degrees19 myservo.write(pos); // tell servo to go to position in variable ‘pos’20 delay(15); // waits 15ms for the servo to reach the position21 }22}

Suggested changes

The content on docs.arduino.cc is facilitated through a public GitHub repository. You can read more on how to contribute in the contribution policy.

License

The Arduino documentation is licensed under the Creative Commons Attribution-Share Alike 4.0 license.

Step 3: How It Works

Servos are clever devices. Using just one input pin, they receive the position from the Arduino and they go there. Internally, they have a motor driver and a feedback circuit that makes sure that the servo arm reaches the desired position. But what kind of signal do they receive on the input pin?

It is a square wave similar to PWM. Each cycle in the signal lasts for 20 milliseconds and for most of the time, the value is LOW. At the beginning of each cycle, the signal is HIGH for a time between 1 and 2 milliseconds. At 1 millisecond it represents 0 degrees and at 2 milliseconds it represents 180 degrees. In between, it represents the value from 0–180. This is a very good and reliable method. The graphic makes it a little easier to understand.

Remember that using the Servo library automatically disables PWM functionality on PWM pins 9 and 10 on the Arduino UNO and similar boards.

Code breakdown

The code simply declares the servo object and then initializes the servo by using the servo.attach() function. We shouldn’t forget to include the servo library. In the loop(), we set the servo to 0 degrees, wait, then set it to 90, and later to 180 degrees.

Wiring Servo Motor to Arduino UNO

Let’s hook the servo motor to the Arduino.

We will be using an SG90 Micro Servo Motor in our experiments. It operates on 4.8-6VDC (5V typical) and can rotate 180 degrees (90 in each direction).

It draws about 10mA when idle and 100mA to 250mA when moving, so we can power it with the Arduino’s 5-volt output.

If your servo consumes more than 250mA, consider using a separate power supply for it.

Connect the red wire to the Arduino’s 5V and the black/brown wire to ground. Finally, attach the Orange/Yellow wire to PWM enabled pin #9.

The following table lists the pin connections:

Servo Motor	Arduino
5V	5V
GND	GND
Control

The image below shows how to connect SG90 servo motor to the Arduino.

Step 5: Check Out More

More topics regarding motors such as brushless, transistor drivers ormotor speed control can be found in my Arduino Development Cookbook available here. 😀

Bài 10: Điều khiển động cơ RC Servo sử dụng Arduino

Tiếp tục trong chuỗi bài viết Khóa học lập trình Arduino Miễn Phí dành cho người nhập môn.

Trong bài viết hôm nay mình sẽ hướng dẫn các bạn làm thế nào để điều khiển góc của một động cơ Servo.

Để có thể hiểu một cách tốt nhất về động cơ RC Servo là gì? Cấu tạo và nguyên lý hoạt động ra làm sao. Các bạn xem bài viết bên dưới nhé.

Xem thêm: Động cơ RC Servo là gì?

Circuit

Servo motors have three wires: power, ground, and signal. The power wire is typically red, and should be connected to positive pole (+) of your power source. The ground wire is typically black or brown and should be connected to the negative pole (-) of your power source.

The signal pin is typically yellow or orange and should be connected to PWM pin on the board. In these examples, it is pin number 9.

Knob Circuit

For the Knob example, wire the potentiometer so that its two outer pins are connected to power (+5V) and ground, and its middle pin is connected to

on the board. Then, connect the servo motor as shown in the circuit below.

A0


Sweep Circuit

For the Sweep example, connect the servo motor as shown in the circuit below.

How Servo Motors Work?

There are four main components inside of a hobby servo, a DC motor, a gearbox, a potentiometer and a control circuit. The DC motor is high speed and low torque but the gearbox reduces the speed to around 60 RPM and at the same time increases the torque.

The potentiometer is attached on the final gear or the output shaft, so as the motor rotates the potentiometer rotates as well, thus producing a voltage that is related to the absolute angle of the output shaft. In the control circuit, this potentiometer voltage is compared to the voltage coming from the signal line. If needed, the controller activates an integrated H-Bridge which enables the motor to rotate in either direction until the two signals reach a difference of zero.

A servo motor is controlled by sending a series of pulses through the signal line. The frequency of the control signal should be 50Hz or a pulse should occur every 20ms. The width of pulse determines angular position of the servo and these type of servos can usually rotate 180 degrees (they have a physical limits of travel).

Generally pulses with 1ms duration correspond to 0 degrees position, 1.5ms duration to 90 degrees and 2ms to 180 degrees. Though the minimum and maximum duration of the pulses can sometimes vary with different brands and they can be 0.5ms for 0 degrees and 2.5ms for 180 degrees position.

Read More: Stepper Motors and Arduino – The Ultimate Guide

What is a Servo and what makes it precise?

Servos are motors that allow you to precisely control physical movement because they generally move to a position rather than continuously rotating. They are simple to connect and control because the motor driver is built right into them.

Servos contain a small DC motor connected to the output shaft through gears. The output shaft drives a servo horn and is also linked to a potentiometer (pot).

The potentiometer provides position feedback to the error amplifier in the control unit, which compares the current position of the motor to the target position.

In response to the error, the control unit adjusts the motor’s current position so that it matches the desired position.

In control engineering, this mechanism is known as a servomechanism, or servo for short. It is a closed-loop control system that uses negative feedback to adjust the motor’s speed and direction to achieve the desired result.

Keywords searched by users: arduino uno servo motor

Categories: Chi tiết 43 Arduino Uno Servo Motor

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