1. 2015 FRC roboRio C++ and JAVA
Two languages saying the same thing but differently!!!!
Presented By:
Frank Larkin
Lansdale Catholic Robotics, Team 272
Philadelphia PA, Dec. 2016

2. Goals
Get a good understanding of what the control system can and cannot do.
Get a good understanding of how to program in C++ and JAVA
Be able to create your own classes to allow multiple threads for development.
See different programming designs for the FRC robot.
Learn how to get autonomous working well.

3. How will we do it? Eat donut holes and then lunch!
Discuss C++ and JAVA
No rat holing on theory.
Exchange cards, get phone numbers and
Review online resources
Forums, Wiki, bla bla
Review LC and other code to explore possibilities
Get many flavors of the same thing.
Touches many of the approaches available to you
See how other accomplished
Shamelessly steal their stuff.
Thought Games
I ask, you figure it out. Fun!!!!
Hands On
Play until it is time to leave.

4. FRC roboRio Hardware Google:FRC robot control system picture

5. C++ and JAVA Both languages are similar…
Both are somewhat human readable.
Both follow a very similar syntax.
Both are object oriented
Both allow you to declare variables
Integer, long, short, float, double
All numbers that reserve different amounts of space.
Character, string
A way to store letters and words. Not really used too much in robots but we can.
Google: [language] operators
A million Internet sites discuss this topic.
Both are extensible and use something called a class
Bundle all of a things, things into a single thing.
A class’s “things” can be public or they can be private. If private you use public methods to set values to them or get values from them.
Classes can inherit other classes

6. Programming Lexicon Object Class Inheritance
Objects are definitions of things you can use in programming you robot. All objects have state and behavior. They define behavior with the outside world through methods.
Class
A class is the blueprint from which individual objects are created.
Inheritance
Different kinds of objects often have a certain amount in common with each other. Object-oriented programming allows classes to inherit commonly used state and behavior from other classes.
Interface (Java only) (just another class in C++)
In its most common form, an interface is a group of related methods with empty bodies.
Variable
A way to associate some information with a name that we can use in our programs. Some variables are created as static and once created cannot be changed.
Package (Java only) (header file (.h) in C++)
A package is a namespace that organizes a set of related classes and interfaces. Conceptually you can think of packages as being similar to different folders on your computer.

7. Class Inheritance
One class can “inherit” everything from another class
People are several inherited classes.
class mammal
Methods: GetAge(), SetAge(), GetHeartBeat(“bpm”)
class human extends mammal
Methods: GetName(), SetName()
class student extends human
Methods: SetGrade(), GetGrade()
Human.GetAge() still works.

8. How Many Classes?

9. FRC Class Example Joystick
What “things” would you expect from an object called a joystick?
Buttons
Trigger
Top
Other user buttons
Various Axis controllers
X = side to side
Y = forward and back
Z = twist or variable level
Throttle = variable level

10. KISS
Class variables
Public – Everyone can get to them.
Private – You decide who gets to them using set and get. (used in real world)
…a dazzling triumph for aerospace designer and maverick genius Burt Rutan. ... SpaceShipOne' s "pressurization" system is essentially a couple of corks.

11. Motor Basics: Java Examples
import edu.wpi.first.wpilibj.Jaguar;
import edu.wpi.first.wpilibj.Victor;
import edu.wpi.first.wpilibj.Relay;
// creating a Jaguar reference
Jaguar motor1 = new Jaguar(1); // default digital module, channel 1
// setting the desired speed (range of -­1.0 to 1.0)
motor1.set(0.5);
// creating a Victor reference
Victor motor2 = new Victor(2); // default digital module, channel 2
motor2.set(0.25);
// creating a Relay reference
// allowing forward direction only
// default digital module, channel 1
Relay motor3 = new Relay(1, kForward);;
// setting the motor to on and off
motor3.set(kOn);
motor3.set(kOff);

12. Motor Basics: C++ Examples
#include “WPILib.h”;
#include <Jaguar.h>;
#include <Victor.h>;
#include <Relay.h>;
// creating a Jaguar reference
// default digital module,
Jaguar *motor1 = new Jaguar(1); //channel 1
// setting the desired speed (range of -­1.0 to 1.0)
motor1-­>Set(0.5);
// creating a Victor reference
Victor *motor2 = new Victor(2); //channel 2
motor2-­>Set(0.25);
// creating a Relay reference,
// allowing forward direction only
// default digital module
Relay *motor3 = new Relay(1, Relay::kForward); // channel 1
// setting the motor to on and off
motor3-­>Set(Relay::kOn);
motor3-­>Set(Relay::kOff);

13. Sensor Basics: Java Examples
import edu.wpi.first.wpilibj.AnalogChannel;
import edu.wpi.first.wpilibj.DigitalInput;
// Create a reference to an analog sensor
// default analog module, channel 1
AnalogInput ana_sensor1 = new AnalogInput(1);
// Get the average voltage from the analog sensor
double voltage = ana_sensor1.getAverageVoltage();
double distance = ana_sensor1.getValue();
double distance = ana_sensor1.getAverageValue();
// Create a reference to a digital sensor
// default digital module, channel 1
DigitalInput dig_sensor2 = new DigitalInput(1);
// Get the value from the sensor
boolean b_SensorState = sensor2.get();

14. Sensor Basics: C++ Examples
#include <AnalogChannel.h>
#include <DigitalInput.h>
// Create variable pointers for sensors
AnalogChannel *sensor1;
DigitalInput *sensor2;
// Initialize the analog sensor
// default analog module, channel 1
sensor1 = new AnalogChannel(1);
// Get the average voltage from the analog sensor
float voltage = sensor1->GetAverageVoltage();
// Create a reference to a digital sensor
// default digital module, channel 1
sensor2 = new DigitalInput(1);
// Get the value from the sensor
UINT32 value = sensor2->Get();

15. Differences between C++ and JAVA
Import
Brings in external packages or classes to make it available to your code.
C++ Variables must be declared in constructor and then initialized
C++
#include
Preprocessor directive that brings in external definitions to make them available to your code
Actual code is recompiled into libraries and linked in later
What is this ??
->

16. C++ Pointers vs Local Declarations Declaration Section:
Pointers – References to things in memory
Possibly looks cleaner
How most examples are being done.
Declarations – The things in memory
No need for pointers but a little more complicated
Why do I care?
You will see code described both ways. Do not be afraid embrace them.
Declaration Section:
class IterativeDemo : public IterativeRobot {
// Declare variable for the robot drive system
Servo *p_servo;
} Note: * means this is a pointer!
Initialization Section:
IterativeDemo(void)
printf("IterativeDemo Constructor Started\n");
p_servo = new Servo(5); }
Usage:
p_servo->Set(.50);
p_servo->Set(p_leftStick->GetZ());

17. Declared Example Declaration Section: Initialization Section: Usage:
class IterativeDemo : public IterativeRobot {
// Declare variable for the robot drive system
Servo m_servo;
Joystick m_leftStick;
Joystick m_RightStick;
Joystick m_OperatorStick; }
Initialization Section:
IterativeDemo(void) : servo(5), leftStick(), rightStick(), operatorStick()
Usage:
m_servo.Set( leftStick.GetZ() );
How do I keep it all straight?
Liberal use of variable prefixes can help.
p_servo, p_leftJoystick; = pointers
i_count = integer (not a pointer)
ip_speed = integer pointer (may never see this).
f_motorPower = floating point variable
M_stuff = member variable (used in many beta examples)
This should scare you…..
p_servo.Set(5);

18. Death By Pointer Java uses pointers under the covers.
Java makes sure you cannot hurt yourself.
What happens if you do it wrong?
It will compile
The Driver Station will show Ok
It will not run.
“Slow Blinking LED of Doom!”

19. Death By Pointer Startup of program on cRIO
Exception current instruction address: 0x012eb5c8
Machine Status Register: 0x0000b032
Data Access Register: 0x537fb81b
Condition Register: 0x
Data storage interrupt Register: 0x
Task: 0x1307e98 "FRCRobotTask"
0x1307e98 (FRCRobotTask): task 0x1307e98 has had a failure and has been stopped.
0x1307e98 (FRCRobotTask): fatal kernel task-level exception!
Welcome to LabVIEW Real-Time 8.5.1
Indicator Mode changed... Slow Blink
Driver Station shows correctly
Do not panic over the slow blink of death!
May be a pointer issue. Do a code review looking for illegal use of pointers.
p_servo.Set(0.0); // p_ indicates pointer!!!
p_servo->Set(0.0); // correct

20. Good Boot Up Startup of program on cRIO Resync command from DS...
Enabled!
Booting watchdog!
Indicator Mode changed... Steady On
WPILib was compiled from SVN revision 1330:1345
Spawned FRCRobotTask (0x12f7b70)
RobotIterativeBase Constructor Start
RobotIterativeBase Constructor Finish
IterativeDemo Constructor Started
IterativeDemo Constructor Completed
RobotIterativeBase StartCompetition() Commenced
Teleop_Init() completed
Welcome to LabVIEW Real-Time 8.5.1

21. Making It All Work Inputs with Java
// Declaration and Initialization in one step
DriverStation m_Dstation = new DriverStation.getInstance();
Joystick m_DriverStick = new Joystick(1);
Joystick m_OperatorStick = new Joystick(2);
Analog a_IRSensor = new Analog(0);
// Use
double d_DYAxis = m_DriverStick.getY();
double d_DXAxis = m_DriverStick.getX();
double f_DTrigger = m_DriverStick.getTrigger();
int i_AutoMode = m_Dstation.getAnalog(1);

22. Making It All Work Inputs with C++
// Declaration
DriverStation *p_DStation;
Joystick *p_DriverStick;
Joystick *p_OperatorStick;
int i_AutoMode;
float f_DYAxis, f_DXAxis; f_DTrigger;
// Initialization
p_DriverStick = new Joystick(1);
p_OperatorStick = new Joystick(2);
// Use
f_DYAxis = p_DriverStick->GetY();
f_DXAxis = p_DriverStick->GetX();
f_DTrigger = p_DriverStick->GetTrigger();
i_AutoMode = p_Dstation.GetAnalog(1);
Later inputs are fed to outputs.

23. Making It Work Floating point power ranges Percentage of power
Stated as range is -1.0 to 1.0 with 0.0 being stop.
Forward and Back are relative
2 motors side by side set to (1.0) are running at full power. But what direction?
All relative to the motors position, gearing, wheels surface top vs. bottom
Joysticks Y axis
Backwards to what you might think?
Push forward get a value of -1.0.
Pull back get 1.0

24. Inputs to Outputs Inputs are fed to outputs
JAVA
m_LeftDriveMotor.set(f_DYaxis)
C++
p_LeftDriveMotor->Set(f_DYaxis)
What about the right motor?

25. Inputs to Outputs Right Motor opposite side of the robot
Will normally have to go in opposite direction to match left motor.
JAVA
m_LeftDriveMotor.set(f_DYaxis)
m_RightDriveMotor.set(-f_DYaxis)
C++
p_LeftDriveMotor->Set(f_DYaxis)
p_RightDriveMotor->Set(-f_DYaxis)

26. Cooking The Inputs Sometimes we “cook” the inputs What will this do?
Joystick gives us percentage of power. 1.0 to -1.0
float tmp = my_joystick.getY();
Squaring: multiply input by itself
driverY = tmp * tmp;
Qubing: multiplying input 3 times
driverY = tmp * tmp * tmp;
What will this do?

27. Cooking The Inputs

28. Discoveries Use excel to help figure out value ranges
Simple math is your friend!
Joystick “twist” comes in a GetZ()
Range 1.0 to -1.0
What does this do?
my.f_Power = ( (-my.p_LeftDriverStick->GetZ() + 1) /2);
Use excel to help figure out value ranges

29. Robot Class Types SimpleRobot Google: frc2168 FRC robot
A simple robot base class that knows the standard FRC competition states (disabled, autonomous, or operator controlled).
You can build a simple robot program off of this by overriding the robotinit(), disabled(), autonomous() and operatorControl() methods.
The startCompetition() method will calls these methods (sometimes repeatedly). depending on the state of the competition.
Alternatively you can override the robotMain() method and manage all aspects of the robot yourself.
Google: frc2168 FRC robot

30. Class Types Iterative Robot
Think giant loop that is run 50 times per second.
System is designed to poll you different classes for updates or settings.
One Method…
Inputs – Get Driver inputs
Sensors – Read the sensors
Robot Think – Make decisions
RobotBase – Update to the motors
Other Classes
More to come…

31. Robot Class Types IterativeRobot (JAVA)
implements a specific type of Robot Program framework, extending the RobotBase class.
The IterativeRobot class is intended to be subclassed by a user creating a robot program. This class is intended to implement the "old style" default code.
import edu.wpi.first.wpilibj.IterativeRobot;
public class MyRobot extends IterativeRobot {
public void robotInit() { … }
public void disabledInit() { … }
public void disabledPeriodic() { … }
public void autonomousInit() { … }
public void autonomousPeriodic() { … }
public void teleopInit() { … }
public void teleopPeriodic() { … } }

32. Robot Class Types IterativeRobot (C++)
class My2011Robot : public IterativeRobot
{ // data member declarations …
public:
MyRobot(void) { // constructor }
void RobotInit() { // initialization }
void DisabledInit() { … }
void DisabledContinious() { … }
void DisabledPeriodic() { … }
void AutonomousInit() { … }
void AutonomousContinious () { … }
void AutonomousPeriodic() { … }
void TeleopInit() { … }
void TeleopContinious () { … }
void TeleopPeriodic() { … }
// team-specific methods … };
START_ROBOT_CLASS(My2011Robot);

33. Robot Class Types IterativeRobot
FMS tells code which mode be in at any time, disabled, autonomous or teleop.
Code runs in fast loop
Too fast for sensors
Continuous routines are called in every loop, good or bad?
50 times per second code drops into appropriate Periodic function. (Called polling)
F-117 only polls 40 times per second!
When FMS switches state, init function is run only once.
When robot first boots up what state are we in?

34. LC Approach Variables Major Code sections inputs.readInputs()
Put all your variables into structure (C++) or a class (Java).
Input – All your input variables
Sensors – All non-driver station sensors
Robot - RobotThink make decisions
Robotbase – all outputs
Other Classes…
Major Code sections
inputs.readInputs()
Read in and pre-cook DS into variables
sensors.GetRobotSensorInputs()
Read in all non DS sensors. Cook as necessary
robot.robotthink()
Decide what to do. Manipulate inputs vars to robotBase vars
robotbase.updateOutputs()
Update outputs variables

35. LC Approach Teleoperated
public void teleopPeriodic() { inputs.readValues(); sensors.readValues(); robotThink(); robotbase.update(); tower.update(inputs, sensors); wedge.update(inputs, sensors); inputs.outputToDashboard(); sensors.outputToDashboard(); robotbase.outputToDashboard(); tower.outputToDashboard(); wedge.outputToDashboard(); auton.outputToDashboard(); }

36. Autonomous
public void autonomousPeriodic() { inputs.zeroValues(); //not used in autoon sensors.readValues(); auton.dispatcher(inputs, sensors, wedge); robotThink(); robotbase.update(); tower.update(inputs, sensors); wedge.update(inputs, sensors); inputs.outputToDashboard(); sensors.outputToDashboard(); auton.outputToDashboard(); robotbase.outputToDashboard(); tower.outputToDashboard(); wedge.outputToDashboard(); }

37. Look At Other’s Code
Google: frc399 james-bot
Many classes
Autonomous

38. Batch Files
Use batch files to quickly change computer ethernet connection.
You must know what your connection is called.

39. netsh Command netsh – used to set network parameters
Command: netsh /? To see parameters
Example: Set interface to Crio
Note: In the example above the netsh command is on the same line!
@echo off
echo Setting the Ip to CRIO network
netsh interface ip set address name="Local Area Connection" static
pause

40. Many batches Set to camera
Set to DHCP Note: All the above commands are set on the same batch line.
netsh interface ip set address name="Local Area Connection" static
netsh interface ip set address name="Local Area Connection" dhcp

41. Final Thought
Unlike baseball crying is allowed in software development… but …
…when you’re done, get back and make it work!