Encoder

Introduction

The encoder class is used with the Optical Shaft Encoder, which measures the rotational position and speed of a shaft. It uses internal optical sensors to detect how far and how fast the shaft turns, making it useful for tracking wheel rotation, arm position, or other mechanisms.

Class Constructor

encoder(
  triport::port &port );

Class Destructor

Destroys the encoder object and releases associated resources.

virtual ~encoder();

Parameters

Parameter	Type	Description
port	triport::port &	The first 3-Wire Port of a required two-port group used by the Optical Shaft Encoder. The encoder occupies two adjacent ports (A–B, C–D, E–F, or G–H) on either the Brain or a 3-Wire Expander. Specify the first port in the pair (A, C, E, or G), written as Brain.ThreeWirePort.X or ExpanderName.X where X is the port letter (for example, Brain.ThreeWirePort.A or Expander1.C).

Examples

// Create an encoder instance in Ports A and B
encoder EncoderA = encoder(Brain.ThreeWirePort.A);

Member Functions

The encoder class includes the following member functions:

• setPosition — Sets the encoder’s current position to a specified value.

• position — Returns how far the encoder has rotated.

• velocity — Returns the current rotational velocity of the encoder.

Before calling any encoder member functions, a encoder instance must be created, as shown below:

/* This constructor is required when using VS Code.
Encoder configuration is generated automatically
in VEXcode using the Device Menu. Replace the values
as needed. */

// Create an encoder instance in Ports A and B
encoder EncoderA = encoder(Brain.ThreeWirePort.A);

setPosition

Sets the encoder’s current position to a specified value. This can be used to manually set the tracked position without rotating a motor or other mechanism.

Available Functions

void setPosition(
  double        value,
  rotationUnits units);

Parameters

Parameters	Type	Description
value	double	The rotational position to set.
units	rotationUnits	The unit that represents the position: deg / degrees — degrees turns / rev — revolutions

Return Values

This function does not return a value.

position

Returns how far the shaft connected to the encoder has rotated.

Available Functions

double position(
  rotationUnits units );

Parameters

Parameters	Type	Description
units	rotationUnits	The unit that represents the position: deg / degrees — degrees turns / rev — revolutions

Return Values

Returns a double representing the rotation in the specified units.

velocity

Returns the rotational velocity of the encoder.

Available Functions

double velocity(
  velocityUnits units );

Parameters

Parameters	Type	Description
units	velocityUnits	The unit used to represent the velocity: percent / pct — percent rpm — rotations per minute dps — degrees per second

Return Values

Returns a double representing the velocity in the specified units.