Motors & Encoders

• Description
• Encoder
  • Header
  • Initialization
  • Usage
• PWM Servo
  • Header
  • Initialization
  • Percent Output
• CAN Spark Max
  • Header
  • Initialization
  • Percent Output
  • Idle Mode
  • Encoder
  • PID Controller
• CAN Talon FX
  • Header
  • Initialization
  • Percent Output
  • Idle Mode
  • Encoder
  • PID Controller
• CAN Talon SRX
  • Header
  • Initialization
  • Percent Output
  • Idle Mode
  • Encoder
  • PID Controller
• CANCoder
  • Header
  • Initialization
  • Absolute Position
• Spark
  • Header
  • Initialization
  • Percent Output

Description

This section covers the basics of using different kinds of motor controllers and encoders. Motors are typically controlled through either PWM or CAN. PWM is a protocol that uses a single wire to send data to the motor controller, so it cannot provide back any information or sensor data from the motor. CAN is more advanced and allows for more information to be sent to and from the motor controller, such as configuration data, encoder position, temperature, current draw, etc.

Encoder

Typically when using dedicated encoders, you can use the frc::Encoder class.

Header

#include <frc/Encoder.h>

Initialization

frc::Encoder encoder{0, 1};

Usage

encoder.Get(); // Position (in ticks)
encoder.GetRate(); // Velocity (RPM)

PWM Servo

PWM Servos can be controlled with the frc::Servo class.

Header

#include <frc/Servo.h>

Initialization

frc::Servo servo { 0 };

Percent Output

servo.Set(0.5);

CAN Spark Max

CAN Spark Max motor controllers are used to control REV motors, such as Neos or Neo 550s. They can be controlled with the rev::CANSparkMax class.

Header

#include <rev/CANSparkMax.h>

Initialization

frc::CANSparkMax motor { 0, rev::CANSparkMax::MotorType::kBrushless }; // kBrushless or kBrushed

Percent Output

motor.Set(0.5);

Idle Mode

motor.SetIdleMode(rev::CANSparkMax::IdleMode::kCoast); // kCoast or kBrake

Encoder

rev::SparkMaxRelativeEncoder encoder(motor.GetEncoder());
double position = encoder.GetPosition();
double velocity = encoder.GetVelocity();

PID Controller

rev::SparkMaxPIDController pidController = motor.GetPIDController();
// Configure the PID Controller
pidController.SetP(0.1);
pidController.SetI(0.0);
pidController.SetD(0.0);
pidController.SetFF(0.0);
pidController.SetIZone(0.0);
// Set the reference (kVelocity, kPosition, kCurrent, etc.).
pidController.SetReference(1.0, rev::ControlType::kVelocity);

CAN Talon FX

CAN Talon FX motor controllers are used to control CTRE motors, predominantly the Falcon 500. They can be controlled with the ctre::phoenix::motorcontrol::can::TalonFX class.

Header

#include <ctre/Phoenix.h>

Initialization

ctre::phoenix::motorcontrol::can::TalonFX motor { 0 };

Percent Output

motor.Set(ctre::phoenix::motorcontrol::ControlMode::PercentOutput, 0.5);

Idle Mode

motor.SetNeutralMode(ctre::phoenix::motorcontrol::NeutralMode::Coast); // Coast or Brake

Encoder

double position = motor.GetSelectedSensorPosition(0);
double velocity = motor.GetSelectedSensorVelocity(0);

PID Controller

motor.Config_kP(0, 0.1);
motor.Config_kI(0, 0.0);
motor.Config_kD(0, 0.0);
motor.Config_kF(0, 0.0);
motor.Config_IntegralZone(0, 0.0);
// Set the reference (Position, Velocity, Current, etc.).
motor.Set(ctre::phoenix::motorcontrol::TalonFXControlMode::Velocity, 1.0);

CAN Talon SRX

CAN Talon FX motor controllers are used to control CTRE motors, predominantly the Falcon 500. They can be controlled with the ctre::phoenix::motorcontrol::can::TalonSRX class.

Header

#include <ctre/Phoenix.h>

Initialization

ctre::phoenix::motorcontrol::can::TalonSRX motor { 0 };

Percent Output

motor.Set(ctre::phoenix::motorcontrol::ControlMode::PercentOutput, 0.5);

Idle Mode

motor.SetNeutralMode(ctre::phoenix::motorcontrol::NeutralMode::Coast); // Coast or Brake

Encoder

double position = motor.GetSelectedSensorPosition(0);
double velocity = motor.GetSelectedSensorVelocity(0);

PID Controller

motor.Config_kP(0, 0.1);
motor.Config_kI(0, 0.0);
motor.Config_kD(0, 0.0);
motor.Config_kF(0, 0.0);
motor.Config_IntegralZone(0, 0.0);
// Set the reference (Position, Velocity, Current, etc.).
motor.Set(ctre::phoenix::motorcontrol::TalonSRXControlMode::Velocity, 1.0);

CANCoder

The CTRE CANCoder is an absolute encoder, meaning that it’s position won’t reset when the robot is powered off. They can be controlled with the ctre::phoenix::sensors::CANCoder class.

Header

#include <ctre/Phoenix.h>

Initialization

ctre::phoenix::sensors::CANCoder canCoder { 0 };

// Signed_PlusMinus180 or Unsigned_0_to_360
canCoder.ConfigAbsoluteSensorRange(ctre::phoenix::sensors::AbsoluteSensorRange::Signed_PlusMinus180);

Absolute Position

canCoder.GetAbsolutePosition();

Spark

PWM Spark motor controllers can be controlled with the frc::Spark class.

Header

#include <frc/Spark.h>

Initialization

frc::Spark motor { 0 };

Percent Output

motor.Set(0.5);