Threads

Introduction

Threads allow a robot to run multiple tasks simultaneously within the same program. They enable multitasking, letting the robot perform independent actions at the same time.

Note: You must first define a function to use it with a thread.

Constructor – Create and start new threads.

• thread – Starts a new thread that runs the specified function in parallel with the main program.

Action – Control running threads.

• interrupt – Stops a thread manually, useful for halting background behavior.

Constructor

thread

thread creates and starts a thread. When you create a thread, you can name it to manage it individually in your project.

Usage:

thread myThread = thread(myFunction);

Parameters	Description
myThread	Optional. A name for the new thread.
myFunction	The name of a previously defined function.

Note: A function must always be defined before it is called.

// Drive forward while blinking screen
void blinkScreen() {
  while (true) {
    Brain.Screen.clearScreen(red);
    wait(0.5, seconds);
    Brain.Screen.clearScreen();
    wait(0.5, seconds);
  }
}

int main() {
  // Initializing Robot Configuration. DO NOT REMOVE!
  vexcodeInit();
  // Begin project code
  thread blinkScreenThread = thread(blinkScreen);
  Drivetrain.drive(forward);
}

// Run multiple threads simultaneously
// Turn right, blink screen at once
void blinkScreen() {
  while (true) {
    Brain.Screen.clearScreen(red);
    wait(0.5, seconds);
    Brain.Screen.clearScreen();
    wait(0.5, seconds);
  }
}

void turning() {
  Drivetrain.turn(right);
}

int main() {
  // Initializing Robot Configuration. DO NOT REMOVE!
  vexcodeInit();
  // Begin project code
  thread blinkScreenThread = thread(blinkScreen);
  thread turningThread = thread(turning);
}

Action

interrupt

interrupt stops a thread manually, which is useful when a task is no longer needed or when a program needs to reset or reassign threads. Once a thread is stopped, it cannot be restarted. To run it again, you must create a new thread using thread.

Usage:
myThread.interrupt();

Parameters	Description
myThread	A previously started thread object. This is the name assigned when the thread was created using thread.

// Loop through red and green
void colorLoop() {
  while (true) {
    Brain.Screen.drawRectangle(0, 120, 480, 120, red);
    wait(0.5, seconds);
    Brain.Screen.drawRectangle(0, 120, 480, 120, green);
    wait(0.5, seconds);
  }
}

// Display the current heading
void displayHeading() {
  Brain.Screen.setFont(prop60);
  while (true) {
    Brain.Screen.clearLine(1);
    Brain.Screen.setCursor(1, 1);
    Brain.Screen.print(
      "Heading: %.1f",
      DrivetrainInertial.heading(degrees)
    );
    wait(50, msec);
  }
}

int main() {
  // Initializing Robot Configuration. DO NOT REMOVE!
  vexcodeInit();

  // Turn right, change screen color, and display heading at once
  thread colorThread = thread(colorLoop);
  thread displayHeadingThread = thread(displayHeading);

  Drivetrain.turn(right);
  wait(2, seconds);

  // Stop the flashing colors
  colorThread.interrupt();
}