1. Session 11
Intro to FRC API

2. What is an API? API stands for application programming interface
It’s a set of routines, protocols, and tools for building software
You can think of it as a bunch of classes that does stuff for us
If we didn’t have an API, programming a robot in 6 weeks would be impossible for most people

3. New Robot Project Go to File > New > Other…
Open the “WPILib Robot Java Development” folder
Select “Robot Java Project” and click next
If you don’t have that folder: /m/13809/l/ installing- eclipse-c-java

4. 3 Main Types of Robot Projects
Command-Based Robot
A more complicated project for more complicated robots
Iterative Robot
Much more simple, but functionality is more limited
Sample Robot
Just the raw basics. Used for testing small things, or for highly advanced control flow.

5. New Robot Project Give your project a name Leave the package as is
That’s how packages are supposed to be named
Select “Iterative Robot”
Click “Finish”

6. Looking at your new project
Robot.java – the main class
Referenced Libraries – the API
wpilib – main robot stuff
networktables – network communication stuff
JRE System Library – what java version the project runs on

7. Robot.java IterativeRobot – the parent class
robotInit() – called when the robot starts up
periodic methods – called periodically while the robot is running
All of these methods were inherited from IterativeRobot

8. FRC Driver Station
The software that controls the robot from your computer
First tab is the operation tab (left half of the screen)

9. Robot Run Modes TeleOperated – a human controls the robot
Autonomous – the robot does stuff itself
Practice – a simulation of a real match
Test – anything you want it to be

10. Misc Information Elapsed Time – how long the robot has been running
PC stats
Window – how the DS appears
windowed / fullscreen
Team Station – where you are
Can get this from the API

11. Robot Information Team # - ours is 5002 Battery Voltage – battery life
Communications – if the DS can “see” the roboRIO
Robot Code – if the roboRIO has code on it
Joysticks – if a joystick is plugged in

12. Logs The log shows errors that happen while the robot’s running
The chart shows packet loss % and other information about the roboRIO
Third tab is both of them at once

13. Driver Station: Diagnostics Tab
Shows what the DS can communicate with
FMS – Field Management System, the thing at a competition
Lets you reboot roboRIO
Also shows version and memory usage

14. Driver Station: Setup Tab
Team Number – determines what IP the DS looks for
Practice Timing – the timing of practice mode
Don’t touch dashboard type and protocols for now

15. Driver Station – USB Devices Tab
Shows any joysticks plugged in
Says what buttons are pressed
Gives values of the axes

16. Driver Station – Power & CAN Tab
Faults – very bad errors
CAN Metrics – we’ll get into later

17. Motor Controllers They control motors via a signal from the roboRIO
Simple ones use a PWM signal
Advanced ones use CAN

18. Robot Wiring PWM ports on the right control basic motor controllers
Use the number on the port to determine which one you’re controlling in code

19. Classes for a Basic Program
Joystick – gets axes and buttons from a joystick
Constructor takes which port the joystick is plugged into
Talon – controls a standard Talon SR motor controller
Constructor takes the PWM port it’s plugged into
RobotDrive – a utility class that drives a robot
Constructor takes the motor controllers

20. Writing the Code: Declaring Variables
Declare your variables
If you get an error, then the classes haven’t been imported
Hover over it with your mouse and select the “Import” option

21. Writing the Code: Initializing Variables
Make a constructor and initialize your variables in it
First joystick will be 0
Need to look at roboRIO for the PWM ports of the Talons
RobotDrive takes those motor controller objects

22. Writing the Code: TeleOp
Driving around the robot in teleop is as easy as this line of code:
arcadeDrive takes a joystick object and uses it to control the robot
The true is for squared inputs
Makes lower values of the axes less sensitive
Allows for more precise control over the robot

23. Writing the Code: Autonomous
Set a motor controller’s speed manually by using the method public void set(double speed)
0 is neutral, -1 is full reverse, 1 is full forward

24. Uploading the Code Connect to the roboRIO (USB, ethernet, or wireless)
Run the project as “WPILib Java Deploy”
Wait for the roboRIO to load the new code
Run the robot