📋Tasks

Multithreading made simple

Tasks allow the code to execute multiple functions simultaneously. For example, one task could handle the driving inputs, and another task could spin a catapult or flywheel at the same time.

Tasks themselves are functions that return an integer (it's C++, go along with it). You can put whatever code you want inside of it, but usually there's a while loop so actions within the task execute more than once. Here's a basic task (called myTask) that spins a flywheel forward:

int myTask() {
  while (true) {
    //do something here
    Flywheel.spin(forward); //just an example
    wait(25, msec);
  }
  
  return 0; //C++ technicality
}

Tasks can be created with this line of code, and will not run until they have been created. The variable spinFlywheel stores the task internally for future reference.

task spinFlywheel = task(myTask);

If you want the task to stop running, call the stop() function on it:

spinFlywheel.stop();

We recommend using tasks for controlling lifts, catapults, or flywheels when the control algorithm required is non-trivial.

Example

Here's an example of using a task to spin a motor when a distance sensor detects an object. Let's start by making the task itself:

int spinMotorTask() {
  while (true) {
    if (DistanceSensor.objectDistance(mm) < 50) {
      Motor.spin(forward, 11, volt); //spin the motor when the distance sensor picks up an object
    } else {
      Motor.stop(); //stop the motor when the sensor doesn't
    }
    
    wait(20, msec); //don't hog the CPU
  }
  
  return 0; //C++ technicality
}

Now, in the main function, we'll call the task like so:

task myTask = task(spinMotorTask);

This code checks every 20 milliseconds to see if the distance sensor detects an object, and spins the motor forward if it does.