INAV supports a buzzer which is used for the following purposes:
- Low and critical battery alarms (when battery monitoring enabled)
- Arm/disarm tones (and warning beeps while armed)
- Notification of calibration complete status
- TX-AUX operated beeping - useful for locating your aircraft after a crash
- Failsafe status
- Flight mode change
- Rate profile change (via TX-AUX switch)
If the arm/disarm is via the control stick, holding the stick in the disarm position will sound a repeating tone. This can be used as a lost-model locator.
Three beeps immediately after powering the board means that the gyroscope calibration has completed successfully. INAV calibrates the gyro automatically upon every power-up. It is important that the copter stay still on the ground until the three beeps sound, so that gyro calibration isn't thrown off. If you move the copter significantly during calibration, INAV will detect this, and will automatically re-start the calibration once the copter is still again. This will delay the "three beeps" tone. If you move the copter just a little bit, the gyro calibration may be incorrect, and the copter may not fly correctly. In this case, the gyro calibration can be performed manually via stick command, or you may simply power cycle the board.
There is a special arming tone used if a GPS fix has been attained, and there's a "ready" tone sounded after a GPS fix has been attained (only happens once). The tone sounded via the TX-AUX-switch will count out the number of satellites (if GPS fix).
The CLI command play_sound is useful for demonstrating the buzzer tones. Repeatedly entering the command will play the various tones in turn. Entering the command with a numeric-index parameter (see below) will play the associated tone.
Buzzer is enabled by default on platforms that have buzzer connections.
Buzzer tone sequences (square wave generation) are made so that : 1st, 3rd, 5th, .. are the delays how long the beeper is on and 2nd, 4th, 6th, .. are the delays how long beeper is off. Delays are in milliseconds/10 (i.e., 5 => 50ms).
Sequences:
0 GYRO_CALIBRATED 20, 10, 20, 10, 20, 10 Gyro is calibrated
1 RX_LOST_LANDING 10, 10, 10, 10, 10, 40, 40, 10, 40, 10, 40, 40, 10, 10, 10, 10, 10, 70 SOS morse code
2 RX_LOST 50, 50 TX off or signal lost (repeats until TX is okay)
3 DISARMING 15, 5, 15, 5 Disarming the board
4 ARMING 30, 5, 5, 5 Arming the board
5 ARMING_GPS_FIX 5, 5, 15, 5, 5, 5, 15, 30 Arming and GPS has fix
6 BAT_CRIT_LOW 50, 2 Battery is critically low (repeats)
7 BAT_LOW 25, 50 Battery is getting low (repeats)
8 NULL multi beeps GPS status (sat count)
9 RX_SET 10, 10 RX is set (when aux channel is set for beep or beep sequence how many satellites has found if GPS enabled)
10 ACC_CALIBRATION 5, 5, 5, 5 ACC inflight calibration completed
11 ACC_CALIBRATION_FAIL 20, 15, 35, 5 ACC inflight calibration failed
12 READY_BEEP 4, 5, 4, 5, 8, 5, 15, 5, 8, 5, 4, 5, 4, 5 GPS locked and copter ready
13 NULL multi beeps Variable # of beeps (confirmation, GPS sat count, etc)
14 DISARM_REPEAT 0, 100, 10 Stick held in disarm position (after pause)
15 ARMED 0, 245, 10, 5 Board is armed (after pause ; repeats until board is disarmed or throttle is increased)
You can use this tool to hear current buzzer sequences or enter custom sequences.
The usage of the buzzer can be controlled by the CLI beeper command.
beeper
beeper list
giving:
Available: RUNTIME_CALIBRATION HW_FAILURE RX_LOST RX_LOST_LANDING DISARMING ARMING ARMING_GPS_FIX BAT_CRIT_LOW
BAT_LOW GPS_STATUS RX_SET ACTION_SUCCESS ACTION_FAIL READY_BEEP MULTI_BEEPS DISARM_REPEAT ARMED SYSTEM_INIT
ON_USB LAUNCH_MODE CAM_CONNECTION_OPEN CAM_CONNECTION_CLOSED ALL PREFERED
The beeper command syntax follows that of the feature command; a minus (-) in front of a name disables that function.
So to disable the beeper / buzzer when powered by USB (may enhance domestic harmony):
beeper -ON_USB
Now the beeper command will show:
# beeper
Disabled: ON_USB
Note: SYSTEM_INIT sequence is not affected by ON_USB setting and will still be played on USB connection. Disable both ON_USB and SYSTEM_INIT to disable buzzer completely when FC is powered from USB.
Note: ON_USB setting requires present and configured battery voltage metter.
To disable all features use:
beeper -ALL
To store current set to preferences use (preferences also require save):
beeper PREFERED
To restore set from preferences use:
beeper -PREFERED
As with other CLI commands, the `save` command is needed to save the new settings.
## Types of buzzer supported
Most FCs require ACTIVE buzzers. Active buzzers are enabled/disabled by simply enabling or disabling a GPIO output pin on the board.
This means the buzzer must be able to generate its own tone simply by having power applied to it.
Passive buzzers that need an analog or PWM signal do not work and will make clicking noises or no sound at all.
Passive buzzers are supported on FCs which are designed to work with passive buzzers only (so far there is no available, except rare cases like Matek F765-WSE where passive buzzer is preinstalled).
Examples of a known-working buzzers.
* [Hcm1205x Miniature Buzzer 5v](http://www.rapidonline.com/Audio-Visual/Hcm1205x-Miniature-Buzzer-5v-35-0055)
* [5V Electromagnetic Active Buzzer Continuous Beep](https://inavflight.com/shop/s/bg/943524)
* [Radio Shack Model: 273-074 PC-BOARD 12VDC (3-16v) 70DB PIEZO BUZZER](http://www.radioshack.com/pc-board-12vdc-70db-piezo-buzzer/2730074.html#.VIAtpzHF_Si)
* [MultiComp MCKPX-G1205A-3700 TRANSDUCER, THRU-HOLE, 4V, 30MA](http://uk.farnell.com/multicomp/mckpx-g1205a-3700/transducer-thru-hole-4v-30ma/dp/2135914?CMP=i-bf9f-00001000)
* [3-24V Piezo Electronic Tone Buzzer Alarm 95DB](https://inavflight.com/shop/s/bg/919348)