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Servo Component

The servo component supports “RC” or “hobby” servo motors. These are small motors with built-in potentiometer position sensors, enabling you to control the angular position of the servo precisely.

As servos can use a lot of power, drawing voltage away from a board, you should power your servo with its own power supply in most cases. The following shows an example wiring diagram for a hobby servo wired to a pi board:

A diagram showing the signal wire of a servo connected to pin 16 on a Raspberry Pi. The servo’s power wires are connected to a 4.8V power supply.

The colors of the servo wires in this diagram may not match your servo. Refer to your servo’s data sheet for wiring specifications.

Most machines with a servo need at least the following hardware:

A board component that can run viam-server
A servo
A power supply for the board
A power supply for the servo

Frame System

Data Management

Tip

The Viam servo component supports hobby servos.

If your motor is coupled with an encoder, not a potentiometer, for position feedback, you should not configure it as a servo. Check your device’s data sheet and configure that type of servo as an encoded motor.

Supported models

To use your servo component, check whether one of the following models supports it.

For configuration information, click on the model name:

RDK
micro-RDK

Model

Description

Add support for other models

If none of the existing models fit your use case, you can create a modular resource to add support for it.

Model	Description
`gpio`	A hobby servo.

Add support for other models

If none of the existing models fit your use case, you can create a modular resource to add support for it.

The micro-RDK works differently from the RDK, so creating modular resources for it is different. Refer to the Micro-RDK Module Template on GitHub for information on how to create custom resources for your micro-RDK machine. You will need to recompile and flash your ESP32 yourself instead of using Viam’s prebuilt binary and installer.

To use your servo component, check whether one of the following models supports it.

For configuration information, click on the model name:

Model

Description

Add support for other models

If none of the existing models fit your use case, you can create a modular resource to add support for it.

Control your servo with Viam’s client SDK libraries

To get started using Viam’s SDKs to connect to and control your machine, go to your machine’s page on the Viam app, navigate to the CONNECT tab’s Code sample page, select your preferred programming language, and copy the sample code generated.

API key and API key ID

By default, the sample code does not include your machine API key and API key ID. We strongly recommend that you add your API key and API key ID as an environment variable and import this variable into your development environment as needed.

To show your machine’s API key and API key ID in the sample code, toggle Include secret on the CONNECT tab’s Code sample page.

Caution

Do not share your API key or machine address publicly. Sharing this information could compromise your system security by allowing unauthorized access to your machine, or to the computer running your machine.

When executed, this sample code will create a connection to your machine as a client. Then control your machine programmatically by adding API method calls as shown in the following examples.

These examples assume you have a servo called "my_servo" configured as a component of your machine. If your servo has a different name, change the name in the code.

Be sure to import the servo package for the SDK you are using:

Python
Go

from viam.components.servo import Servo

import (
  "go.viam.com/rdk/components/servo"
)

API

The servo component supports the following methods:

Method Name	Description	micro-RDK Support
`Move`	Move the servo to the desired angle in degrees.
`GetPosition`	Get the current set angle of the servo in degrees.
`GetGeometries`	Get all the geometries associated with the servo in its current configuration, in the frame of the servo.
`IsMoving`	Returns whether the servo is actively moving (or attempting to move) under its own power.
`Stop`	Stop the servo from moving.
`Reconfigure`	Reconfigure this resource.
`DoCommand`	Execute model-specific commands that are not otherwise defined by the component API.
`FromRobot`	Get the resource from the provided robot with the given name.
`GetResourceName`	Get the `ResourceName` for this servo with the given name.
`Close`	Safely shut down the resource and prevent further use.

Move

Move the servo to the desired angle in degrees.

Stability Notice

Support for continuous servos with the GPIO servo model is experimental. Stability is not guaranteed. Breaking changes are likely to occur, and occur often.

If you are using a continuous rotation servo, you can use the Move command, but instead of moving to a given position, the servo will start moving at a set speed.

The speed will be related to the “angle” you pass in as a linear approximation. 90 degrees represents stop, 91 to 180 represents counter-clockwise rotation from slowest to fastest, and 89 to 1 represents clockwise from slowest to fastest. It is recommended that you test your servo to determine the desired speed.

Supported by the micro-RDK.

Parameters:

angle (int) (required): The desired angle of the servo in degrees.
extra (Mapping[str, Any]) (optional): Extra options to pass to the underlying RPC call.
timeout (float) (optional): An option to set how long to wait (in seconds) before calling a time-out and closing the underlying RPC call.

Returns:

None.

Example:

my_servo = Servo.from_robot(robot=robot, name="my_servo")

# Move the servo from its origin to the desired angle of 10 degrees.
await my_servo.move(10)

# Move the servo from its origin to the desired angle of 90 degrees.
await my_servo.move(90)

For more information, see the Python SDK Docs.

Parameters:

ctx (Context): A Context carries a deadline, a cancellation signal, and other values across API boundaries.
angleDeg (uint32): The desired angle of the servo in degrees.
extra (map[string]interface{}): Extra options to pass to the underlying RPC call.

Returns:

(error): An error, if one occurred.

Example:

// Move the servo from its origin to the desired angle of 30 degrees.
myServoComponent.Move(context.Background(), 30, nil)

For more information, see the Go SDK Docs.

Parameters:

angle int (required)
extra Map<String, dynamic>? (optional)

Returns:

Future<void>

For more information, see the Flutter SDK Docs.

GetPosition

Get the current set angle of the servo in degrees. Supported by the micro-RDK.

Parameters:

extra (Mapping[str, Any]) (optional): Extra options to pass to the underlying RPC call.
timeout (float) (optional): An option to set how long to wait (in seconds) before calling a time-out and closing the underlying RPC call.

Returns:

(int): The current angle of the servo in degrees.

Example:

my_servo = Servo.from_robot(robot=robot, name="my_servo")

# Move the servo from its origin to the desired angle of 10 degrees.
await my_servo.move(10)

# Get the current set angle of the servo.
pos1 = await my_servo.get_position()

# Move the servo from its origin to the desired angle of 20 degrees.
await my_servo.move(20)

# Get the current set angle of the servo.
pos2 = await my_servo.get_position()

For more information, see the Python SDK Docs.

Parameters:

ctx (Context): A Context carries a deadline, a cancellation signal, and other values across API boundaries.
extra (map[string]interface{}): Extra options to pass to the underlying RPC call.

Returns:

(uint32): The current set angle of the servo in degrees.
(error): An error, if one occurred.

Example:

// Get the current set angle of the servo.
pos1, err := myServoComponent.Position(context.Background(), nil)

// Move the servo from its origin to the desired angle of 20 degrees.
myServoComponent.Move(context.Background(), 20, nil)

// Get the current set angle of the servo.
pos2, err := myServoComponent.Position(context.Background(), nil)

logger.Info("Position 1: ", pos1)
logger.Info("Position 2: ", pos2)

For more information, see the Go SDK Docs.

Parameters:

extra Map<String, dynamic>? (optional)

Returns:

Future<int>

Example:

var angle = await myServo.position();

For more information, see the Flutter SDK Docs.

GetGeometries

Get all the geometries associated with the servo in its current configuration, in the frame of the servo. The motion and navigation services use the relative position of inherent geometries to configured geometries representing obstacles for collision detection and obstacle avoidance while motion planning.

Python

Parameters:

extra (Mapping[str, Any]) (optional): Extra options to pass to the underlying RPC call.
timeout (float) (optional): An option to set how long to wait (in seconds) before calling a time-out and closing the underlying RPC call.

Returns:

(List[viam.proto.common.Geometry]): The geometries associated with the Component.

Example:

geometries = await component.get_geometries()

if geometries:
    # Get the center of the first geometry
    print(f"Pose of the first geometry's centerpoint: {geometries[0].center}")

For more information, see the Python SDK Docs.

IsMoving

Returns whether the servo is actively moving (or attempting to move) under its own power.

Parameters:

timeout (float) (optional): An option to set how long to wait (in seconds) before calling a time-out and closing the underlying RPC call.

Returns:

(bool): Whether the servo is moving.

Example:

my_servo = Servo.from_robot(robot=robot, name="my_servo")

print(my_servo.is_moving())

For more information, see the Python SDK Docs.

Parameters:

ctx (Context): A Context carries a deadline, a cancellation signal, and other values across API boundaries.

Returns:

(bool): Whether this resource is moving (true) or not (false).
(error): An error, if one occurred.

Example:

// This example shows using IsMoving with an arm component.
myArm, err := arm.FromRobot(machine, "my_arm")

// Stop all motion of the arm. It is assumed that the arm stops immediately.
myArm.Stop(context.Background(), nil)

// Log if the arm is currently moving.
is_moving, err := myArm.IsMoving(context.Background())
logger.Info(is_moving)

For more information, see the Go SDK Docs.

Parameters:

None.

Returns:

Future<bool>

Example:

var isItMoving = await myServo.isMoving();

For more information, see the Flutter SDK Docs.

Stop

Stop the servo from moving. Supported by the micro-RDK.

Parameters:

extra (Mapping[str, Any]) (optional): Extra options to pass to the underlying RPC call.
timeout (float) (optional): An option to set how long to wait (in seconds) before calling a time-out and closing the underlying RPC call.

Returns:

None.

Example:

my_servo = Servo.from_robot(robot=robot, name="my_servo")

# Move the servo from its origin to the desired angle of 10 degrees.
await my_servo.move(10)

# Stop the servo. It is assumed that the servo stops moving immediately.
await my_servo.stop()

For more information, see the Python SDK Docs.

Parameters:

ctx (Context): A Context carries a deadline, a cancellation signal, and other values across API boundaries.
extra (map[string]interface{}): Extra options to pass to the underlying RPC call.

Returns:

(error): An error, if one occurred.

Example:

// This example shows using Stop with an arm component.
myArm, err := arm.FromRobot(machine, "my_arm")

// Stop all motion of the arm. It is assumed that the arm stops immediately.
err = myArm.Stop(context.Background(), nil)

For more information, see the Go SDK Docs.

Parameters:

extra Map<String, dynamic>? (optional)

Returns:

Future<void>

Example:

await myServo.stop();

For more information, see the Flutter SDK Docs.

Reconfigure

Reconfigure this resource. Reconfigure must reconfigure the resource atomically and in place.

Parameters:

ctx (Context): A Context carries a deadline, a cancellation signal, and other values across API boundaries.
deps (Dependencies): The resource dependencies.
conf (Config): The resource configuration.

Returns:

(error): An error, if one occurred.

For more information, see the Go SDK Docs.

DoCommand

Execute model-specific commands that are not otherwise defined by the component API. For built-in models, model-specific commands are covered with each model’s documentation. If you are implementing your own servo and add features that have no built-in API method, you can access them with DoCommand. Supported by the micro-RDK.

Parameters:

command (Mapping[str, ValueTypes]) (required): The command to execute.
timeout (float) (optional): An option to set how long to wait (in seconds) before calling a time-out and closing the underlying RPC call.

Returns:

(Mapping[str, viam.utils.ValueTypes]): Result of the executed command.

Raises:

(NotImplementedError): Raised if the Resource does not support arbitrary commands.

Example:

command = {"cmd": "test", "data1": 500}
result = component.do(command)

For more information, see the Python SDK Docs.

Parameters:

ctx (Context): A Context carries a deadline, a cancellation signal, and other values across API boundaries.
cmd (map[string]interface{}): The command to execute.

Returns:

(map[string]interface{}): The command response.
(error): An error, if one occurred.

Example:

// This example shows using DoCommand with an arm component.
myArm, err := arm.FromRobot(machine, "my_arm")

command := map[string]interface{}{"cmd": "test", "data1": 500}
result, err := myArm.DoCommand(context.Background(), command)

For more information, see the Go SDK Docs.

Parameters:

command Map<String, dynamic> (required)

Returns:

Future<Map<String, dynamic>>

Example:

// Example using doCommand with an arm component
const command = {'cmd': 'test', 'data1': 500};
var result = myArm.doCommand(command);

For more information, see the Flutter SDK Docs.

FromRobot

Get the resource from the provided robot with the given name.

Flutter

Parameters:

robot RobotClient (required)
name String (required)

Returns:

Servo

For more information, see the Flutter SDK Docs.

GetResourceName

Get the ResourceName for this servo with the given name.

Python
Flutter

Parameters:

name (str) (required): The name of the Resource.

Returns:

(viam.proto.common.ResourceName): The ResourceName of this Resource.

Example:

# Can be used with any resource, using an arm as an example
my_arm_name = my_arm.get_resource_name("my_arm")

For more information, see the Python SDK Docs.

Parameters:

name String (required)

Returns:

ResourceName

Example:

// Example:
var name = Servo.getResourceName('myServo');

For more information, see the Flutter SDK Docs.

Close

Safely shut down the resource and prevent further use.

Python
Go

Parameters:

None.

Returns:

None.

Example:

await component.close()

For more information, see the Python SDK Docs.

Parameters:

ctx (Context): A Context carries a deadline, a cancellation signal, and other values across API boundaries.

Returns:

(error): An error, if one occurred.

Example:

// This example shows using Close with an arm component.
myArm, err := arm.FromRobot(machine, "my_arm")

err = myArm.Close(ctx)

For more information, see the Go SDK Docs.

Troubleshooting

You can find additional assistance in the Troubleshooting section.

You can also ask questions in the Community Discord and we will be happy to help.

Next steps

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Servo Component

Related services

Tip

Supported models

Add support for other models

Add support for other models

Add support for other models

Control your servo with Viam’s client SDK libraries

API key and API key ID

Caution

API

Move

Stability Notice

GetPosition

GetGeometries

IsMoving

Stop

Reconfigure

DoCommand

FromRobot

GetResourceName

Close

Troubleshooting

Next steps