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Titan Robotics 2022 Preseason Training Repository

Welcome to the Titan Robotics programming subteam.

Contents

Homework

VSCode and Git

  1. Checkout Training2022/git-lesson
  2. Create a branch off of that branch called <yourname>-git-lesson
  3. Push a commit that adds a file named <yourname>.txt to your new branch
  4. Merge your branch into Training2022/git-lesson and make sure this change is pushed

Introduction to Motors and Controllers

In a branch called yourname-motors off of the motors branch, write a program that uses some sort of input from an XboxController to control a WPI_TalonFX motor. Explicitly set the neutral mode of the motor. Don't forget to push your code (you don't need to merge the branch). For an extra (optional) challenge, create multiple motors and control them using a joystick, a button, and a trigger.

Links and Resources

Here are some useful links that will be useful during training. You aren't expected to go check them out right now, but they're here for anyone who wants a preview of the kinds of things we'll go over.

VSCode and Git

Introduction to Motors and Controllers

Command Based Programming: Subsystems

Command Based Programming: Commands

NetworkTables and the FRC Control System

CAN for Programming

Introduction to Advanced Topics

Limelight Tuning and Other Sensors

Quick Reference

Git Review

Create a branch: git checkout -b your-branch-name

Stage changes: git add .

Commit staged changes: git commit -m "a short description of your changes"

Publish a new branch: git push -u origin your-branch-name

Switch to another existing branch: git checkout other-branch-name

Check for updates: git pull

Merge a branch into the branch you are on: git merge your-branch-name

Motors

WPI_TalonFX constructor: WPI_TalonFX(int id) (id is the CAN id of the motor controller)

Control Modes:

  • motor.set(ControlMode.PercentOutput, pct) - -1.0 < pct < 1.0
  • motor.set(ControlMode.Velocity, vel) - vel is in ticks per 100ms (requires an encoder and a PID index to be selected)
  • motor.set(ControlMode.Position, pos) - pos is in ticks (requires an encoder and a PID index to be selected)

Neutral Modes:

  • motor.setNeutralMode(NeutralMode.Brake) motor provides resistance to turning
  • motor.setNeutralMode(NeutralMode.Coast) motor coasts to a stop without providing resistance

Inverting Directions:

  • motor.setInverted(true/false)
  • motor.setSensorPhase(true/false)

Encoder Initialization:

  • motor.configSensorInitializationStrategy(SensorInitializationStrategy.BootToZero, 0) zeros the integrated encoder on startup
  • motor.configSensorInitializationStrategy(SensorInitializationStrategy.BootToAbsolutePosition, 0) uses absolute orientation for the integrated encoder

Selecting an Encoder and PID index:

  • motor.configSelectedFeedbackSensor(TalonFXFeedbackDevice.IntegratedSensor, idx, 0) selects the integrated encoder for PID index idx (usually 0)
  • motor.selectProfileSlot(idx, 0) tells the motor to use PID index idx (usually 0)

Controllers / Gamepads

XboxController constructor: XboxController(int port) (port is the USB port the controller is plugged into)

Joysticks: xbox.getLeftX(), xbox.getLeftY(), xbox.getRightX(), and xbox.getRightY() return values from -1.0 to +1.0. The left Y stick is reversed.

Buttons:

  • xbox.getXButton() returns true if the X button is currently pressed
  • xbox.getXButtonPressed() returns true if the X button was pressed since the last time it was checked
  • xbox.getXButtonReleased() returns true if the X button was released since the last time it was checked
  • xbox.getLeftTrigger(), xbox.getRightTrigger(), xbox.getLeftStickButton(), and xbox.getRightStickButton() work the same way, with the same three variants.

Triggers: xbox.getLeftTriggerAxis() and xbox.getRightTriggerAxis() return values from 0.0 to 1.0.