> For the complete documentation index, see [llms.txt](https://yagsl.yassrobotics.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://yagsl.yassrobotics.com/reference/api-reference.md). # API Reference YAGSL's own Java surface is intentionally small: `SwerveParser` reads your [JSON config](/reference/json-schema.md) and hands you back a fully-built **YAMS** `SwerveDrive`. From that point on, you're driving and configuring a YAMS object, not a YAGSL-specific one, so the authoritative API reference lives in the YAMS docs, not here. ## YAGSL packages YAGSL 2027 is split into a command framework agnostic core and one small package per WPILib command framework. Which packages you have depends on the [vendordep you installed](/reference/vendordep-installation.md). | Package | Artifact | What's in it | | --------------------------------------------------------- | ----------------- | --------------------------------------------------------------------------------------------------------------------------------------- | | `swervelib.commands2` | `YAGSL-commands2` | `SwerveParser` for Commands v2. Returns a `yams.commands2.swerve.SwerveDrive` bound to your `Subsystem`. | | `swervelib.commands3` | `YAGSL-commands3` | `SwerveParser` for Commands v3. Returns a `yams.commands3.swerve.SwerveDrive` bound to your `Mechanism`. | | `swervelib.core.parser` | `YAGSL-core` | The base `SwerveParser` (JSON reading, the `SwerveDriveDevices` / `SwerveModuleDevices` records), `CANBuses`, `PIDFConfig`. | | `swervelib.core.parser.json` (and `.json.modules`) | `YAGSL-core` | The classes each JSON file is read into: `SwerveDriveJson`, `ModuleJson`, `DeviceJson`, `PhysicalPropertiesJson`, `PIDFPropertiesJson`. | | `swervelib.core.parser.deserializer` (and `.reflections`) | `YAGSL-core` | `ReflectionsManager` and the per-vendor device classes, loaded by reflection. | | `swervelib.core.telemetry` | `YAGSL-core` | `SwerveDriveTelemetry`. | The pre-2027 `swervelib.parser.*` and `swervelib.telemetry.*` packages are now `swervelib.core.parser.*` and `swervelib.core.telemetry.*`. Robot code should import `SwerveParser` from `swervelib.commands2` or `swervelib.commands3`, not from `swervelib.core.parser`. ## SwerveParser entry points Every method is `static`. Parse the directory first, then create the drive: {% tabs %} {% tab title="Commands v2" %} ```java import swervelib.commands2.SwerveParser; import yams.commands2.config.SwerveDriveConfig; import yams.commands2.swerve.SwerveDrive; var cfg = new SwerveDriveConfig().withSubsystem(this); SwerveParser.parse(new File(Filesystem.getDeployDirectory(), "swerve/base")); SwerveDrive drive = SwerveParser.createSwerveDrive(cfg); ``` {% endtab %} {% tab title="Commands v3" %} ```java import swervelib.commands3.SwerveParser; import yams.commands3.config.SwerveDriveConfig; import yams.commands3.swerve.SwerveDrive; var cfg = new SwerveDriveConfig().withMechanism(this); SwerveParser.parse(new File(Filesystem.getDeployDirectory(), "swerve/base")); SwerveDrive drive = SwerveParser.createSwerveDrive(cfg); ``` {% endtab %} {% endtabs %} | Method | Defined in | What it does | | ----------------------------------------------------------------- | ----------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `SwerveParser.parse(File directory)` | `swervelib.core.parser.SwerveParser` | Reads the JSON directory into the static `swerveDriveJson`, `pidfPropertiesJson`, `physicalPropertiesJson` and `moduleJsons` fields. Throws `UncheckedIOException` if a file can't be read. | | `SwerveParser.parseDirectory(File directory)` | `swervelib.core.parser.SwerveParser` | Same, but throws the checked `IOException`. | | `SwerveParser.readJson(File file, Class type)` | `swervelib.core.parser.SwerveParser` | Reads one JSON file into one of the `swervelib.core.parser.json` classes. | | `SwerveParser.createSwerveDrive(SwerveDriveConfig config)` | `swervelib.commands2.SwerveParser` / `swervelib.commands3.SwerveParser` | Builds the modules and gyro from the parsed JSON, applies them to your `SwerveDriveConfig`, and returns the framework's `SwerveDrive`. | | `SwerveParser.createSwerveDriveDevices(SwerveDriveConfig config)` | `swervelib.commands2.SwerveParser` / `swervelib.commands3.SwerveParser` | Same, but returns a `SwerveDriveDevices` record: `swerveDrive()`, `gyro()` and `modules()` (one `SwerveModuleDevices` per module, with `drive()`, `azimuth()` and `absoluteEncoder()`). | {% hint style="warning" %} `parse(...)` returns a core `swervelib.core.parser.SwerveParser`, which has no `createSwerveDrive`. The 2026 style chain `SwerveParser.parse(dir).createSwerveDrive(cfg)` and the older `new SwerveParser(dir).createSwerveDrive(cfg)` no longer compile. Call the two static methods one after the other, as shown above. {% endhint %} `SwerveParser.createSwerveDriveDevices(config)` is the one place YAGSL hands back something other than YAMS objects: alongside the `SwerveDrive`, it returns the raw vendor motor controller/encoder/ gyro objects it built, for the rare case where you need to call a vendor-specific method `SmartMotorController` doesn't expose. `gyro()` is `null` for a `custom` gyro. See [How to access raw hardware devices](/how-to-guides/access-raw-hardware-devices.md). ## YAMS classes you get back | Class | Commands v2 | Commands v3 | YAMS API reference | | ------------------------------------------------------------- | ------------------------------------------------ | ----------------------------------------- | ------------------------------------------------------------------------------------------------------------ | | `SwerveDrive` | `yams.commands2.swerve.SwerveDrive` | `yams.commands3.swerve.SwerveDrive` | [SwerveDrive](https://yagsl.gitbook.io/yams/api-reference/java-reference/swerve/swerve-drive) | | `SwerveDriveConfig` | `yams.commands2.config.SwerveDriveConfig` | `yams.commands3.config.SwerveDriveConfig` | [SwerveDriveConfig](https://yagsl.gitbook.io/yams/api-reference/java-reference/swerve/swerve-drive-config) | | `SwerveInputStream` | `yams.commands2.swerve.SwerveInputStream` | `yams.commands3.swerve.SwerveInputStream` | [SwerveInputStream](https://yagsl.gitbook.io/yams/api-reference/java-reference/swerve/swerve-input-stream) | | `SwerveModule` (per-module) | `yams.core.mechanisms.swerve.SwerveModule` | same | [SwerveModule](https://yagsl.gitbook.io/yams/api-reference/java-reference/swerve/swerve-module) | | `SwerveModuleConfig` (built internally from your module JSON) | `yams.core.mechanisms.config.SwerveModuleConfig` | same | [SwerveModuleConfig](https://yagsl.gitbook.io/yams/api-reference/java-reference/swerve/swerve-module-config) | The framework specific `SwerveDrive` and `SwerveDriveConfig` extend the shared `yams.core.mechanisms.swerve.SwerveDrive` and `yams.core.mechanisms.config.SwerveDriveConfig`, which is where most of their methods are documented. The full YAMS API reference (all mechanisms, motor controllers, units, and math helpers, not just swerve) is at [yagsl.gitbook.io/yams](https://yagsl.gitbook.io/yams/api-reference/java-reference). ## Javadoc | Library | Javadoc | | ------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | YAGSL | [yet-another-software-suite.github.io/YAGSL/javadocs](https://yet-another-software-suite.github.io/YAGSL/javadocs/) | | `swervelib.commands2.SwerveParser` | [SwerveParser (Commands v2)](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/commands2/SwerveParser.html) | | `swervelib.commands3.SwerveParser` | [SwerveParser (Commands v3)](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/commands3/SwerveParser.html) | | `swervelib.core.parser.SwerveParser` | [SwerveParser (core)](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/core/parser/SwerveParser.html) | | `swervelib.core.parser.CANBuses` | [CANBuses](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/core/parser/CANBuses.html) | | `swervelib.core.parser.json` | [JSON classes](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/core/parser/json/package-summary.html) | | YAMS | [yet-another-software-suite.github.io/YAMS/javadocs](https://yet-another-software-suite.github.io/YAMS/javadocs/) | | YAMS `SwerveDrive` | [Commands v2](https://yet-another-software-suite.github.io/YAMS/javadocs/yams/commands2/swerve/SwerveDrive.html), [Commands v3](https://yet-another-software-suite.github.io/YAMS/javadocs/yams/commands3/swerve/SwerveDrive.html), [core](https://yet-another-software-suite.github.io/YAMS/javadocs/yams/core/mechanisms/swerve/SwerveDrive.html) | | YAMS `SwerveDriveConfig` | [Commands v2](https://yet-another-software-suite.github.io/YAMS/javadocs/yams/commands2/config/SwerveDriveConfig.html), [Commands v3](https://yet-another-software-suite.github.io/YAMS/javadocs/yams/commands3/config/SwerveDriveConfig.html), [core](https://yet-another-software-suite.github.io/YAMS/javadocs/yams/core/mechanisms/config/SwerveDriveConfig.html) | {% hint style="info" %} Only `SwerveParser` and the JSON-file classes under `swervelib.core.parser.json` are YAGSL-specific. If you find yourself calling a method on `SwerveDrive`, `SwerveModule`, `SwerveDriveConfig`, `SwerveModuleConfig`, or `SwerveInputStream`, you're looking at YAMS API. Go to the links above, not the YAGSL source, for the authoritative docs and Javadoc. {% endhint %} ## Where to look for what * **"What JSON fields exist?"** → [JSON Schema Reference](/reference/json-schema.md) (this site). * **"What does `SwerveDrive.drive(...)` do, what are all its methods?"** → [YAMS SwerveDrive reference](https://yagsl.gitbook.io/yams/api-reference/java-reference/swerve/swerve-drive). * **"How do I build a `SwerveDriveConfig` by hand instead of from JSON?"** → [YAMS SwerveDriveConfig reference](https://yagsl.gitbook.io/yams/api-reference/java-reference/swerve/swerve-drive-config). * **"How do I wire joystick input into field/robot-relative chassis velocities?"** → [YAMS SwerveInputStream reference](https://yagsl.gitbook.io/yams/api-reference/java-reference/swerve/swerve-input-stream). * **"Which CAN bus does a `canbus` value mean?"** → [Control system and CAN buses](/reference/json-schema.md#control-system-and-can-buses). * **"What changed in the JSON schema or the API recently?"** → [Schema Changes](/reference/schema-changes.md). --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://yagsl.yassrobotics.com/reference/api-reference.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.