Hello OpMode

Welcome to your first FTC programming lesson! Every FTC robot program starts in one place: an OpMode. By the end of this lesson, you will understand what an OpMode is, how it is structured, and you will write your very first one.

What is an OpMode?

An OpMode (short for "Operational Mode") is the entry point for all FTC robot programs. Think of it like the main() function in a regular Java program -- it is where the Robot Controller looks to find out what your robot should do.

Every time a driver selects your program on the Driver Station and presses Init, the Robot Controller creates an instance of your OpMode and starts running it.

There are two types of OpModes in the FTC SDK:

• OpMode -- Uses a callback-based structure with init(), loop(), stop() methods. Good for advanced use cases.
• LinearOpMode -- Runs your code top-to-bottom in a single runOpMode() method. Much easier to read and reason about.

The Structure of a LinearOpMode

Here is the skeleton of every LinearOpMode you will write:

@TeleOp(name = "My OpMode")
public class MyOpMode extends LinearOpMode {
    @Override
    public void runOpMode() {
        // INITIALIZATION CODE
        // Runs when the driver presses Init
waitForStart();
// RUNNING CODE
        // Runs when the driver presses Play
    }
}

There are three key parts to understand:

1. @TeleOp annotation -- This registers your OpMode so it appears on the Driver Station. You can also use @Autonomous for autonomous programs.
2. Initialization phase -- Any code before waitForStart() runs as soon as the driver presses Init. Use this to set up hardware, display status info, and get ready.
3. Running phase -- Code after waitForStart() runs once the driver presses Play. This is where your robot actually does things.

Telemetry: Talking to the Driver Station

Your robot cannot talk, but it can display messages on the Driver Station screen using telemetry. This is invaluable for debugging and for giving drivers real-time information.

Here is how telemetry works:

telemetry.addData("Caption", "Value");
telemetry.update();

• addData(caption, value) adds a line of data to the telemetry buffer. The caption is a label, and the value is what gets displayed next to it.
• update() sends the buffered data to the Driver Station screen. Without calling update(), nothing will appear!

telemetry.addData("Status", "Initialized");
telemetry.addData("Team", "12345");
telemetry.update();  // Both lines appear at once

Your Exercise

Time to write your first OpMode! Your task is to:

1. Before waitForStart(): Display a telemetry message with caption "Message" and value "Hello, FTC!", then call telemetry.update().
2. After waitForStart(): Display a telemetry message with caption "Status" and value "Running", then call telemetry.update().

Give it a try in the editor below!