# Sensors

## What is a `Sensor`?

A `Sensor` is a wrapper around what would be a real sensor on your robot, like a `CanandColor`, beam break, `CANRange`, `LaserCAN`, or anything else! While some of these have really good simulation capabilities; others have no simulation capabilities.

Sensors essentially report back primitive values. Sometimes we know the sensor should trip at a certain time during the match, like autonomous, or under certain conditions like game piece trade offs or intaking for a second or more. Sometimes we want to trigger the sensor ourselves too!

## How do I create a `Sensor`?

{% hint style="info" %}
Using a `Sensor` wrapper will NEVER be as fast or efficient as using the original input.
{% endhint %}

You can create a sensor using `SensorConfig` which is where you define the Sensor name, and fields.

```java
private DigitalInput dio = new DigitalInput(0); // Standard DIO
private final Sensor coralSensor = new SensorConfig("CoralDetectorBeamBreak") // Name of the sensor 
  .withField("Beam", dio::get, false) // Add a Field to the sensor named "Beam" whose value is dio.get() and defaults to false
  .withSimulatedValue("Beam", Seconds.of(3), Seconds.of(4), true) // Change the "Beam" field to true between 3s and 4s into a match
  .withSimulatedValue("Beam",()->arm.isNear(Degrees.of(40), Degrees.of(2)), true) // Change "Beam" field to true when the arm is near 40deg +- 2deg
  .getSensor(); // Get the sensor.
```

You can use `int`, `long`, `double`, or `bool` as sensor field values.

## How do I add simulated values to a sensor?

You can add simulated values to an existing `Sensor` using `Sensor.addSimTrigger` like below.

<pre class="language-java"><code class="lang-java">private DigitalInput dio = new DigitalInput(0); // Standard DIO
private final Sensor coralSensor = new SensorConfig("CoralDetectorBeamBreak") // Name of the sensor 
  .withField("Beam", dio::get, false) // Add a Field to the sensor named "Beam" whose value is dio.get() and defaults to false
  .withSimulatedValue("Beam", Seconds.of(3), Seconds.of(4), true) // Change the "Beam" field to true between 3s and 4s into a match
  .getSensor(); // Get the sensor.

...
<strong>coralSensor.addSimTrigger("Beam",()->arm.isNear(Degrees.of(40), Degrees.of(2)), true); // Change "Beam" field to true when the arm is near 40deg +- 2deg
</strong></code></pre>

## What does this look like?

<figure><img src="https://1354553280-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FZM0CFmYiQzcrY4zDcTtZ%2Fuploads%2FxZnE2jTxxjCEg91Q7rhP%2Fimage.png?alt=media&#x26;token=bc957101-6b79-4283-a53b-a4e1069017aa" alt=""><figcaption></figcaption></figure>

The circled value changes when the Arm is near 40deg +-2 deg. You can also change it in the Simulation GUI manually.

## How do I use the value from a `Sensor`?

{% hint style="danger" %}
The sensor field value will only automatically update if the sensor is checked!
{% endhint %}

Instead of doing `dio.get()` in the example, you would have to do `coralSensor.getAsBoolean("Beam")` like the example below.&#x20;

<pre class="language-java"><code class="lang-java">public boolean getBeamBreak()
{
  // return dio.get() // Will not work because the value is not modified by Sensor or automatically updated.
<strong>  return coralSensor.getAsBoolean("Beam");
</strong>}
</code></pre>

## How do I simulate the sensor value?

You can set the sensor value manually by getting the field (`.getField`) from a sensor and calling the `.set` function. It will overwrite the previous value of the sensor field until its changed from glass or via `.set` again.

{% hint style="info" %}
This will only change the sensor value when running under simulations. It does not affect the real value whenr unning on the robot.
{% endhint %}

```java
public void setBeamBreakWhenArmIsLow()
{
    new Trigger(arm::isLow).onTrue(Commands.run(()->coralSensor.getField("Beam").set(true)));
}
```