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6.1 Use an Active Buzzer instead of a Passive Buzzer
A buzzer (or tone siren) can be used to audibly indicate aircraft status changes. Depending on the capabilities of the board, it can be an active device (which only needs to apply voltage to produce a single frequency tone), as shown in the diagram below, or a passive piezoelectric device driven by PWM, capable of producing a variable Music tone, as pictured above. Some boards can use both types.
If you use a PWM -capable output with a passive piezo, it can play a variety of sounds , including unlock sounds, mode change sounds, and lost aircraft alarms ( search this page for " lost rotor Aircraft alarm ", search for " lost fixed wing " in RCx_OPTION , such as RC5_OPTION , or search for " lost unmanned vehicle " in auxiliary functions ( Auxiliary Functions ) ).
！Note
In order to use the passive piezo buzzer to play musical notification tones, the autopilot firmware must define this functionality to a pin with a timer in its build definition. This is not a feature that the user can add via parameter setting, unlike using an active mono-tone buzzer by assigning any GPIO- capable pin NTF_BUZZ_PIN .
！Note
Some autopilots (most 1MB flash boards) only offer the ability to use an active beeper, and will provide a limited set of simple beeps instead of musical tones to indicate ARM , DISARM , etc. See the next section for information. However, it is possible to create a custom board firmware that includes the tone alert function. The motor output can then be used to drive the ArduPilot's full range of buzzers, which is handy for boards that only support buzzers. Outputs used must be configured with SERVOx_FUNCTION = 138 or = 139 , depending on the desired signal polarity.
The choice of buzzer must be careful, because the motor/servo output can only provide a small current, so it is better to use a buzzer with independent power supply and amplification function, such as HGLRC Soter FPV drone buzzer ( HGLRC Soter FPV drone buzzer ). The selected buzzer output needs to be in a separate PWM group, i.e. not in the same group as outputs used for other functions, such as ESC DSHOT .
6.1 Use an Active Buzzer instead of a Passive Buzzer
Active buzzers can be used with the passive buzzer board setup in two ways.
First, an active buzzer can simply replace a passive piezo on an autopilot designed to play a tone alert, be careful with the polarity of the buzzer (unlike a passive piezo buzzer, an active buzzer connectors need to be connected with correct polarity for proper operation). It will play all the sounds though, probably at a lower volume and without the exact audio played by the passive buzzer.
Alternatively, you could set NTF_BUZZ_PIN to a GPIO pin, such as those used for relay control ( relay control ), and connect the negative of an active buzzer to that pin, then connect the power supply (usually + 5V ) to the positive pole of the buzzer. This is usually how the " BUZZ " or " BUZZ- " output pins on some autopilot aircraft are used.
If using an active buzzer, the NTF_BUZZ_ON_LVL parameter determines the pin level required to activate it.
If an active buzzer is used, it can indicate the following:
| STATUS |
Pattern |
| unlock |
3 sec long Beep |
| Unlock failed |
Single Beep |
| lock |
Single Beep |
| Battery runaway protection |
Single Beep repeating every 3 sec |
| EKF failure |
Beeeep-Beeep-Beep-Beep |
| lost drone |
Beep-Beep repeating every 3 sec |
！Note
For many boards, GPIO pin numbers are assigned to PWM outputs for alternate use which can only be found by looking at the board's hwdef.dat file ( here ).
6.2 Install the buzzer
If the beeper is placed too close to the autopilot , the sound from the beeper can affect the accelerometer, which can lead to poor altitude hold performance when the beeper is engaged. The buzzer should preferably be installed at least 5cm away from the autopilot , and the speaker (that is, the opening) should not point directly at the autopilot .
6.3 Silence the buzzer
Some autopilots (such as HobbyKing PixRacer ) have a built-in buzzer. We recommend disabling these beepers by setting the following parameters:
- NTF_BUZZ_TYPES controls which types of buzzers are enabled: pin-driven buzzers (internal or external), and/or ESC - based DShot ;
- In firmware prior to 4.1 , set NTF_BUZZ_ENABLE = 0 to disable pin-driven buzzers.
Additionally, NTF_BUZZ_VOLUME can be used to control the volume.