# Absolute Encoders YAGSL supports most common FRC absolute encoders. Absolute encoders are required if you are using a brushed motor . The absolute encoder value will show up in your driver dashboard under `swerve/modules/.../Raw Absolute Encoder` and can be used to tune the `absoluteEncoderOffset` in module JSON configuration files under most circumstances. ## Absolute Encoder Checklist * [ ] All Absolute Encoder's spin counterclockwise positive. * [ ] Magnetic Absolute encoders have a good read on the magnet while still and in operation (while the robot moves). * [ ] Absolute Encoders have unique CAN ID's or Analog Input Channel's. * [ ] Absolute Encoder are defined with the correct ID or Analog Input Channel. * [ ] Absolute Encoders have full range (`0`-`360`) ## Swerve Absolute Encoder Wrapper YAGSL created wrappers over all supported Absolute Encoders to uniformly fetch and set data that is needed for a Swerve Module to operate. This wrapper is called [`SwerveAbsoluteEncoder`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/encoders/SwerveAbsoluteEncoder.html). All [`SwerveAbsoluteEncoder`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/encoders/SwerveAbsoluteEncoder.html)'s can be fetched via the [`SwerveModule`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/SwerveModule.html#configuration) configuration object [`SwerveModuleConfiguration`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/parser/SwerveModuleConfiguration.html) absolute encoder attribute [`absoluteEncoder`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/parser/SwerveModuleConfiguration.html#absoluteEncoder). The [`SwerveModule`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/SwerveModule.html) is able to be fetched by [`SwerveDrive.getModules()`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/SwerveDrive.html#getModules\(\)) easily. YAGSL created wrappers over all supported Motor Controllers to uniformly fetch and set data that is needed for a Swerve Drive to operate. This wrapper is called [`SwerveMotor`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/motors/SwerveMotor.html). All [`SwerveMotor`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/motors/SwerveMotor.html)'s can be fetched via the [`SwerveModule`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/SwerveModule.html#configuration) configuration object [`SwerveModuleConfiguration`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/parser/SwerveModuleConfiguration.html) motor definitions [`angleMotor`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/parser/SwerveModuleConfiguration.html#angleMotor) and [`driveMotor`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/parser/SwerveModuleConfiguration.html#driveMotor). The [`SwerveModule`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/SwerveModule.html) is able to be fetched by [`SwerveDrive.getModules()`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/SwerveDrive.html#getModules\(\)) easily.

import com.ctre.phoenix6.hardware.CANcoder;
 
   /**
   * Initialize {@link SwerveDrive} with the directory provided.
   *
   * @param directory Directory of swerve drive config files.
   */
  public SwerveSubsystem(File directory)
  {
    // Angle conversion factor is 360 / (GEAR RATIO * ENCODER RESOLUTION)
    //  In this case the gear ratio is 12.8 motor revolutions per wheel rotation.
    //  The encoder resolution per motor revolution is 1 per motor revolution.
    double angleConversionFactor = SwerveMath.calculateDegreesPerSteeringRotation(12.8, 1);
    // Motor conversion factor is (PI * WHEEL DIAMETER IN METERS) / (GEAR RATIO * ENCODER RESOLUTION).
    //  In this case the wheel diameter is 4 inches, which must be converted to meters to get meters/second.
    //  The gear ratio is 6.75 motor revolutions per wheel rotation.
    //  The encoder resolution per motor revolution is 1 per motor revolution.
    double driveConversionFactor = SwerveMath.calculateMetersPerRotation(Units.inchesToMeters(4), 6.75, 1);

    // Configure the Telemetry before creating the SwerveDrive to avoid unnecessary objects being created.
    SwerveDriveTelemetry.verbosity = TelemetryVerbosity.HIGH;
    try
    {
      swerveDrive = new SwerveParser(directory).createSwerveDrive(maximumSpeed, angleConversionFactor, driveConversionFactor);
    } catch (Exception e)
    {
      throw new RuntimeException(e);
    }
    swerveDrive.setHeadingCorrection(false); // Heading correction should only be used while controlling the robot via angle.

    for(SwerveModule m : swerveDrive.getModules())
    {
      System.out.println("Module Name: "+m.configuration.name);
      CANcoder absoluteEncoder = (CANcoder)m.configuration.absoluteEncoder.getAbsoluteEncoder();
    }
  }

## Absolute Encoder Configuration {% hint style="warning" %} Only CTRE devices currently support the `canbus` option, if your device is using the roboRIO `canbus` you must use the value of `null` or `"rio"` for supported CTRE devices. If you are using a CANivore, and the device is on the CANivore bus, the name must match the CANivore name. {% endhint %} {% hint style="success" %} If your absolute encoder is attached to your SparkMAX, use the function [`SwerveDrive.pushOffsetsToEncoders()`](https://broncbotz3481.github.io/YAGSL-Lib/docs/swervelib/SwerveDrive.html#pushOffsetsToEncoders\(\)) for the best performance. This sets the onboard PID sensor to the attached encoder! {% endhint %} Inside any module JSON such as `frontleft.json`,`frontright.json`,`backleft.json`,`backright.json` this is what you would see to configure a absolute encoder.

{
  "drive": {
    "type": "sparkmax",
    "id": 5,
    "canbus": null
  },
  "angle": {
    "type": "sparkmax",
    "id": 6,
    "canbus": null
  },
  "encoder": {
    "type": "cancoder",
    "id": 11,
    "canbus": null
  },
  "inverted": {
    "drive": false,
    "angle": false
  },
  "absoluteEncoderOffset": -18.281,
  "absoluteEncoderInverted": false,
  "location": {
    "front": -12,
    "left": -12
  }
}

## Possible Absolute Encoder Types {% hint style="warning" %} Try inverting your steering/angle/azimuth motor if your module keeps spinning around. {% endhint %}

Device	type
None	`none`
Integrated/Attached (via SparkMAX DutyCycle)	`attached`
SparkMax Analog (via SparkMAX Analog Pin)	`sparkmax_analog`
SparkMax Analog (via SparkMAX Analog Pin with 5V power)	`sparkmax_analog5v`
Canandmag (via SparkMAX)	`canandmag`
Canandmag (via CAN)	`canandmag_can`
CANcoder	`cancoder`
Throughbore (via DIO)	`throughbore`
Thrifty Absolute Magnetic Encoder (via Analog Input)	`thrifty`
MA3 (via Analog Input)	`ma3`
SRX Mag (via PWM)	`ctre_mag`
AM Mag (via PWM)	`am_mag`
PWM DutyCycle	`dutycycle`
Analog Encoder	`analog`

[^1]: [`CANcoder`](https://api.ctr-electronics.com/phoenix6/release/java/com/ctre/phoenix6/hardware/CANcoder.html) from Phoenix 6, initialized via CAN bus and CAN ID from configurations. [^2]: [`CANcoder`](https://api.ctr-electronics.com/phoenix6/release/java/com/ctre/phoenix6/hardware/CANcoder.html) from Phoenix 6, initialized via CAN bus and CAN ID from configurations. Cast `Object` to [`CANcoder`](https://api.ctr-electronics.com/phoenix6/release/java/com/ctre/phoenix6/hardware/CANcoder.html) [^3]: SparkMAX brushless mode is selected. [^4]: The SparkMAX has a CAN ID of `5`. [^5]: SparkMAX is not compatible with CANivore so the `canbus` should be `null` or `""`. [^6]: The SparkMAX has a CAN ID of `6`. [^7]: [`CANcoder`](https://api.ctr-electronics.com/phoenix6/release/java/com/ctre/phoenix6/hardware/CANcoder.html) is selected using the CAN ID and bus bellow. [^8]: [`CANcoder`](https://api.ctr-electronics.com/phoenix6/release/java/com/ctre/phoenix6/hardware/CANcoder.html) id for this module. [^9]: CANivore name of which the [`CANcoder`](https://api.ctr-electronics.com/phoenix6/release/java/com/ctre/phoenix6/hardware/CANcoder.html) resides on. [^10]: The drive motor spins counter clockwise positive without any inversion. [^11]: The steering/angle/azimuth motor spins counterclockwise positive without inversion. [^12]: Offset read from `Module[...] Raw Absolute Encoder` when the wheel was facing straight and bevels the same way.\ \ Offsets are in degrees. [^13]: This should rarely, if ever, be true. [^14]: The center of this module is `-12`in from the center of the robot "frontwise". [^15]: The center of this module is `-12`in from the center of the robot "left". [^16]: ```json "encoder": { "type": "attached", "id": 11, "canbus": null }, ``` [^17]: ```json "encoder": { "type": "sparkmax_analog", "id": 11, "canbus": null }, ``` [^18]: ```json "encoder": { "type": "sparkmax_analog5v", "id": 11, "canbus": null }, ``` [^19]: ```json "encoder": { "type": "canandmag", "id": 11, "canbus": null }, ``` [^20]: ```json "encoder": { "type": "canandmag_can", "id": 11, "canbus": null }, ``` [^21]: ```json "encoder": { "type": "cancoder", "id": 11, "canbus": null }, ``` [^22]: ```json "encoder": { "type": "throughbore", "id": 11, "canbus": null }, ``` [^23]: ```json "encoder": { "type": "thrifty", "id": 11, "canbus": null }, ``` [^24]: ```json "encoder": { "type": "ma3", "id": 11, "canbus": null }, ``` [^25]: ```json "encoder": { "type": "ctre_mag", "id": 11, "canbus": null }, ``` [^26]: ```json "encoder": { "type": "am_mag", "id": 11, "canbus": null }, ```