FRC Programming

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FRC Programming

• Languages, Libraries and Tools

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Mikes Stuff

• Industry Overview

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The LabVIEW Language

• A LV program consists of one or more Virtual
  Instruments (VIs)
• A VI is like a function or a procedure or a
  subroutine except that it has a richer interface

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The LabVIEW Language

• A VI is built by describing the flow of data as
  it is transformed by logical, arithmetic, or I/O
  operations
• Thus LV is a dataflow language

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The LabVIEW Language

• A VI is implemented in two windows
• Panel is where user interacts with data
• Diagram is where computer interacts with data

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The LabVIEW Language

• Panel inputs are called controls e.g. a button,
  a switch, a knob
• Outputs are called indicators e.g. a graph or
  chart
• Not going to discuss panels much
• NOTE Inputs and outputs act as parameters as
  well as user interface

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The LabVIEW Language

• A sample block diagram that defines PWM 1 and 2
  as being left and right motors
• Sets the speed to 50, then delays for 1 second

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The LabVIEW Language

• It now drives Fwd for 1 second, then pivots at
  30 for 0.5 second
• Assuming this turns about 90, how would we move
  in a square?

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The LabVIEW Language

• We could copy/paste code three more times, or we
  can use a For loop
• Surround code similar to or begin end
• Also stop motors

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The LabVIEW Language

• Weve now made the square code conditional on a
  driver station digital input
• If True, move in a square

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The LabVIEW Language

• If False, move in an S shape

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The LabVIEW Language

• What does this new code do?
• Hint it turns on a motor to 40 for 4 seconds
• What else?

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The LabVIEW Language

• This is equivalent

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The LabVIEW Language

• Quiz Time ?
• What does this code do?

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The LabVIEW Language

• Compare it to this code?

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Object Oriented Programming

• C C Objects other features
• C programs that dont use the extensions look
  are C programs
• C objects are similar to Java objects
• Java taught in many high schools
• Java used on programming AP exams

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Quick Tour of Objects

• Objects are a good way of representing real-world
  things
• Motors, sensors, driver station, robot drive
  train, your whole robot
• Have data associated with the thing and code
  that operates on the data (member data and
  methods)
• Some objects are more specific versions of other
  objects (subclasses)

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Objects (Classes)
Quadrature Encoder Object
Member Variables
What can it do? GetCount() GetPeriod() Reset()
What does it know? Port numbers Reversed or not
RobotDrive Object
What can it do? Drive() ArcadeDrive() TankDrive()
What does it know? Port numbers Speed controller
type
Methods
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Subclass of a class
SimpleRobot class
Team190Robot class
Autonomous() print message Autonomous
OperatorControl() print message Operator
control
Autonomous() Drive around the field and score
point OperatorControl() Drive our robot
using tank steering
IsAutonomous() return the current field state
IsEnabled() return robot state
Very boring!
Now very cool!
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Objects in sample program
myRobot
RobotDrive Object
Methods RobotDrive(leftmotor, rightmotor) Drive(
speed, curve) Arcade(joystick)
stick
Joystick Object
Methods Joystick(port) GetX() Gety() GetTwist(
)
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Robot Definition
class RobotDemo public SimpleRobot
RobotDrive myRobot Joystick stick //
constructor, Autonomous, and Operator Control go
here START_ROBOT_CLASS(RobotDemo)
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Initialization (constructor)
RobotDemo(void) myRobot(1, 2),
stick(1) GetWatchdog().SetExpiration(100)

Initialize the RobotDrive and Joystick
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Autonomous part of program
void Autonomous(void) GetWatchdog().SetEnabl
ed(false) myRobot.Drive(0.5, 0.0)
Wait(2000) myRobot.Drive(0.0, 0.0)
Use the RobotBase object Drive method to go 0.5
speed (forward, half speed) with no turn
Key to the example myRobot.Drive(speed, curve)
speed a value from -1.0 to 1.0 where 0.0 is
stopped curve a value from -1.0 to 1.0 where
0.0 is no turn
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Object References vs Pointers

• References are pointers without and
• Look like an instance variable
• Guaranteed to be initialized, no NULL
• new returns pointers

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Function Overloading

• Same function name with different parameter types
  can have different implementations
• Example
• Victor(channel)
• OR
• Victor(slot, channel)

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Accessible from C or C

• What if I cant or dont want to write C code?
• Put .cpp at the end of file names
• Write C code, except when referencing WPILib
  objects
• Use C object construction and referencing
  rather than the C method
• Create one class for your robot program
• Everything else looks like C
• C wrappers available soon

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C Example
void Autonomous(void) SetWatchdogEnabled(fals
e) Drive(0.5, 0.0) Wait(2000)
Drive(0.0, 0.0) void OperatorControl(void)
SetWatchdogEnabled(true) while
(IsOperatorControl())
WatchdogFeed() ArcadeDrive(JOYSTICK_PORT)
START_ROBOT_CLASS(SimpleCRobot)

• include "WPILib.h"
• include "SimpleCRobot.h"
• include "CRobotDrive.h"
• static const UINT32 LEFT_MOTOR_PORT 1
• static const UINT32 RIGHT_MOTOR_PORT 2
• static const UINT32 JOYSTICK_PORT 1
• void Initialize(void)
• CreateRobotDrive(LEFT_MOTOR_PORT,
  RIGHT_MOTOR_PORT)
• SetWatchdogExpiration(100)

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The LabVIEW Environment

• The LabVIEW project window organizes source files
  and designates which computer they will run on
• Set IP address to deploy to
• Select code for cRIO to boot

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The LabVIEW Environment

• The VIs are found in the palettes
• If not easily found, use Search

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The LabVIEW Environment

• The context help window describes the object
  under the mouse
• Detailed help link leads to an external full help
  system

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The LabVIEW Environment

• Tutorials
• Breakpoints
• Probes
• Exec Hilighting

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Wind River Tools
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HW Architecture
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Architecture
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WPI Robotics Library

• Presenter Notes
• Open the help system for WindRiver
• Browse to show the SW hierarchy, drill down to
  Victor to review the capabilities of the object
• Open the LV help system, browse to
  WPIgtgtActuatorsgtgtMotors to show the Open, Set
  Speed and Get Speed equivalents
• If you like, visit Gyro or another class

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Vision and Camera Libraries

• Presenter Notes
• Open the help system for WindRiver
• Browse to the Camera section and review acquiring
  images
• Browse to the Image Processing section and review
  color tracking
• Open the LV help system, browse to WPIgtgtCamera to
  show the Open, Get Image and related functions
• Review the First Vision VI documentation

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LabVIEW Frameworks

• Presenter Notes
• From Getting Started screen or New create a
  Robot Project using the Wizard and default
  settings
• Open the Robot Main diagram and review where
  objects are opened, where they are closed, and
  review the TeleOp code
• From the project open the Autonomous Independent
  VI and review the default code.
• In Robot Main discuss the Vision and Periodic
  Loop sections

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LabVIEW Frameworks

• Presenter Notes
• From Getting Started screen or New create a
  Robot Project using the Wizard and click to the
  advanced version
• Open the Robot Main diagram and discuss when
  various VIs will be called.
• Double click on the VIs or open them in the
  project and go over the comments for what Begin,
  Finish, Teleop, Autonomous Iterative, Autonomous
  Independent, Disabled, Vision, and Periodic Tasks
  are used for

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LabVIEW Frameworks

• Basic Picture/description

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LabVIEW Frameworks

• Advanced Picture/description

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C Framework

• Simple
• Iterative

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C Framework
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Dashboard
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Imaging the HW
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Open Source