> For the complete documentation index, see [llms.txt](https://yall.yassrobotics.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://yall.yassrobotics.com/documentation/understanding/hardware-telemetry-and-imu.md).

# Hardware Telemetry & IMU

Newer Limelight firmware (2026+) publishes system health and, on the Limelight 4, onboard IMU data as part of the JSON results frame. All of it lives under `LimelightResults` and is only available through [`getLatestResults()`](/documentation/understanding/results-json-vs-raw-networktables.md) — there's no raw-NT equivalent.

## HardwareReport

`LimelightResults.hardware` reports CPU usage, disk space, RAM usage, and CPU temperature:

```java
limelight.getLatestResults().ifPresent(result -> {
    if (result.hardware != null && result.hardware.getTemp().gt(Celsius.of(70))) {
        // consider throttling — see How do I reduce thermal output while disabled?
    }
});
```

If a Hailo neural accelerator module is installed (Limelight 4 only, sold separately), its stats are nested at `result.hardware.hailoStats` as a `HailoStats` — presence, temperature, power draw, and throttle state.

## IMUResults (Limelight 4)

`LimelightResults.imuResults` exposes the onboard IMU's fused yaw and full 9-axis data (orientation + angular velocity + acceleration):

```java
limelight.getLatestResults().ifPresent(result -> {
    if (result.imuResults != null) {
        Pair<Orientation3d, AngularAcceleration3d> imu = result.imuResults.getIMUData();
        Angle fusedYaw = result.imuResults.getFusedYaw();
    }
});
```

This is a separate concept from `LimelightSettings.withRobotOrientation` — that method **submits** your robot's gyro data *to* the Limelight for MegaTag2 fusion. `IMUResults` **reads back** the Limelight 4's own internal IMU, which is useful for diagnostics or as a fallback orientation source, not as a replacement for your robot's primary gyro. See `LimelightSettings.ImuMode` for how the two interact when both an internal and external IMU are available.

## RewindStats (Limelight 4)

`LimelightResults.rewindStats` reports rolling-buffer status — usage fraction, frame count, and whether a flush to disk is in progress. See [How do I take snapshots and rewind captures?](/documentation/how-to-guides/how-do-i-take-snapshots-and-rewind-captures.md) for triggering captures.

## See Also

* [How do I reduce thermal output while disabled?](/documentation/how-to-guides/how-do-i-reduce-thermal-output-while-disabled.md)
* HardwareReport reference
* IMUResults reference


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