The existing Pixhawk Lite (PHL) board does not provide any standard audio signaling output or buzzer support via the regularly released ArduCopter firmware.
APM:Copter V3.3.2-rc2-lw-rc1 is a custom version of APM:Copter (based on Arducopter V3.3.2-r2) which provides support (via Pixhawk Lite pins AUX1 through AUX6) for both passive audio devices (e.g. passive piezos that can play arbitrary tones) and active audio devices (e.g. buzzers that play a fixed tone).
Full info at: lauren.vortex.com/phl-lw-info.pdf
Signaling melodies/patterns are separately optimized for passive and active audio devices, rather than duplicating Pixhawk “standard” tone sequences. The type of audio device installed is specified via a settable parameter.
Melodies (for passive piezos) and buzz sequences (for active devices, e.g. buzzers) are provided for the following events:
GPS 2d lock
GPS 3d lock
GPS dgps lock
Loss of GPS lock
RC status change (transmitter on/off)
The user can enable and disable the audio signaling, indicate whether they are using a passive or active audio device, select the AUX pin number to be used for the audio device, indicate whether the audio device has a “low” or “high” logic level off (silent) state, and choose a “limited audio signaling” mode with fewer audio signals if desired.