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Buzzer expansion deck

The buzzer deck contains a low profile piezo buzzer and has a 1-wire memory which enables the Crazyflie to automatically detect the deck.

The deck is designed to be installed either on the top or the bottom of the Crazyflie.

Drivers for the buzzer are integrated in the Crazyflie 2.0 firmware.


  • Based on the CMT-1203-SMT
  • 1-wire memory for automatic expansion board detection
  • Designed for mounting over or under the Crazyflie 2.0
  • Mechanical specification:
    • Weight: 1.8g
    • Size (WxHxD): 25x27x4mm


Buzzer expansion deck schematic.

Changing the sounds

Changing the sounds requires modifications to the firmware. The code for the sounds is located in modules/src/sound_cf2.c.

A sequences is defined in the .notes member of the Melody struct. The notes are defined as tuples of a note (pitch) and duration. A sequence must be ended with the end marker.

The effects are defined in the effects array. Each entry takes a function to call and related parameters. To add a new melody, use the melodyplayer function for the .call member and assign your Melody struct to the .melody member.


NameTypeAccessValue (default)Description
sound.effectuint8_tRW0Sound effect (0=Off, 1=Factory test, 2=USB connected, 3=USB disconnected, 4=Charging done, 5=Low battery, 6=Startup, 7=Calibrated, 8=Range slow, 9=Range fast, 10=Star Wars Imperial March, 11=Bypass (change sound with sound.freg), 12=Siren, 13=Tilt (tilt the Crazyflie to play the sound))
sound.neffectuint32_tRO13Number of available sound effects
projects/crazyflie2/expansionboards/buzzer.txt · Last modified: 2021-06-24 16:09 by kimberly