# Tune/Sound Meanings

[Pixhawk-series flight controllers](../../drone_parts/flight_controller/pixhawk_series) use audible tones/tunes and [LEDs](led_meanings) to indicate vehicle state and events (e.g. arming success and failure, low battery warnings).

The set of standard sounds are listed below.

:::note **Developers:** Tunes are defined in [/lib/tunes/tune\_definition.desc](https://github.com/PX4/PX4-Autopilot/blob/main/src/lib/tunes/tune_definition.desc) and can be tested using the [tune-control](../../../development/modules_main/modules_system#tune-control) module. You can search for tune use using the string `TUNE_ID_name`(e.g. \`TUNE\_ID\_PARACHUTE\_RELEASE) :::

## Boot/Startup

These tunes are played during the boot sequence.

#### Startup Tone

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* microSD card successfully mounted (during boot).

#### Error Tune

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* Hard fault has caused a system reboot.
* System set to use PX4IO but no IO present.
* UAVCAN is enabled but driver can't start.
* SITL/HITL enabled but _pwm\_out\_sim_ driver can't start.
* FMU startup failed.

#### Make File System

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* Formatting microSD card.
* Mounting failed (if formatting succeeds boot sequence will try to mount again).
* No microSD card.

#### Format Failed

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* Formatting microSD card failed (following previous attempt to mount card).

#### Program PX4IO

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* Starting to program PX4IO.

#### Program PX4IO Success

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* PX4IO programming succeeded.

#### Program PX4IO Fail

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* PX4IO programming failed.
* PX4IO couldn't start.
* AUX Mixer not found.

## Operational

These tones/tunes are emitted during normal operation.

#### Error Tune

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* RC Loss

#### Notify Positive Tone

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* Calibration succeeded.
* Successful mode change.
* Command accepted (e.g. from MAVLink command protocol).
* Safety switch off (vehicle can be armed).

#### Notify Neutral Tone

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* Mission is valid and has no warnings.
* Airspeed calibration: supply more air pressure, or calibration complete.
* Safety switch turned on/disarmed (safe to approach vehicle).

#### Notify Negative Tone

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* Calibration failed.
* Calibration already completed.
* Mission is invalid.
* Command denied, failed, temporarily rejected (e.g. from MAVLink command protocol).
* Arming/disarming transition denied (e.g. pre-flight checks failed, safety not disabled, system not in manual mode).
* Reject mode transition.

#### Arming Warning

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* Vehicle is now armed.

#### Arming Failure Tune

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* Arming failed

#### Battery Warning Slow

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* Low battery warning ([failsafe](../../../config/safety#low-battery-failsafe)).

#### Battery Warning Fast

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* Critical low battery warning ([failsafe](../../../config/safety#low-battery-failsafe)).

#### GPS Warning Slow

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#### Parachute Release

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* Parachute release triggered.

#### Single Beep

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* Magnetometer/Compass calibration: Notify user to start rotating vehicle.

#### Home Set Tune

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* Home position initialised (first time only).

#### Power Off Tune

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* Vehicle powering off.
