Using ESC Beacon (Motor) as Lost Model Alarm

by Oscar

If you don’t have a buzzer on your FPV drone, you can setup ESC beacon and use your motors as lost model alarm replacement. It’s the same as the start-up beeps that the motors make when you plug in the battery.

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ESC Beacon can be useful when you don’t have a buzzer installed, or in case your buzzer fails in a crash. Check here for more useful tips on quadcopter building/flying.

Warning: running motor beeper for too long could result in overheat, even burns out your motors in some cases. It’s best to set them to beep once or twice then stop.

In this tutorial we will show you how to do this in ESC’s with BLHeli firmware. To set it up there are only 2 settings you need to configure in BLHeliSuite:

  • Beacon Strength – How loud you want the beeper to sound (default 80, range from 1 to 255); 120 is a good value IMO, I suggest trying different values and check if the motors and ESC would get too hot. I don’t recommend setting this too high to prevent motors and ESC overheat
  • Beacon Delay – After how long the beeper starts to activate being idle (default 10mins, IMO 5 or even 2 mins is a good idea for our purpose)

There is also Beep Strength. This setting might seem relevant but actually it’s not. It only controls the volume of the start-up beep, so just leave it as it is.

A bit out of topics, if you’ve ever wondered how ESC’s can make sound, they don’t. It’s actually the motors that makes the sound. The pitch and volume of the sound is controlled by signal from the ESC. It’s even possible to play a jingle with motors :)

Enabling Dshot ESC Beeper in Betaflight

In the latest Betaflight, you can now turn on the motor beeper using a switch! This frees you from using a regular piezo buzzer.

The option is available on the configuration tab, under DShot Beacon Configuration section.

Alternatively you can also set it in CLI:

set beeper_dshot_beacon_tone = 3 save

The setting can be set from 0 to 5. Setting it to 0 will disable motor beeper. Differences between beeper tones 1-5 beep at different intervals and with different pitches. Personally I find tone #3 the “loudest” to hear.

You have RX_SET and RX_LOST options – if you want to activate DShot Beacon with a switch on your radio, enable RX_SET. If you want motors to beep when radio signal is lost, enable RX_LOST.

However, I don’t recommend using RX_LOST. Motor beeper is not very loud, so of you are too far away that your radio can’t get a signal, you are probably also too far away to hear the beeper anyway. If your motors continues to beep for minutes even hours while you are searching for it, there is a big chance that you can fry the motors.

To be able to activate DShot beacon with a switch on your radio, simply assign a switch to the beeper mode in the modes tab. When you flip this switch, the motors and buzzer will beep at the same time.

flight modes - acro mode, horizon mode, angle mode

Edit History

  • Jun 2017 – article created
  • Apr 2019 – added warning about RX_LOST (I think you should disable it)

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DK 25th November 2022 - 12:49 pm

Hi Oscar,
Just curious how do motors generate sound exactly?

Steve 27th December 2021 - 9:35 pm

Other beeper options?

Bob 25th November 2020 - 6:52 pm

You suggested to switch off RX_Lost in betaflight because it might fry the motors.
However you are recommending to enable Beacon Delay in BL Heli, which starts the motor beeps after a few minutes.
Is there any difference between these two? Why is Beacon Delay in BL Heli ok, but RX_Lost is not ok?
Thank You

Daniel 19th November 2020 - 9:50 am

Thanks for this article it helped me much

Charles 29th March 2020 - 11:52 pm

Hey everyone … Revisiting this article (3-2020 Covid 19 times) in the new days of AIO boards and toothpicks. I would prefer to NOT have on board Motor beeper but external piezo buzzer available despite its added weight. (Goal Loudness) !

I can’t specifically tell from the wording in this article if I need to EXPLICITLY set the beacon_tone to 0 (now that I have de-soldered the damn buzzer) in order to get the external buzzer to work. – Yea Im-ma gonna solder it back on and try but in case anyone else ends up here from Backwards googling like I did,,, does anyone know the answer before I go test, and come back here to update this question with my results ?

Bruno Gomes 14th April 2019 - 12:41 am

The beacon tone in Betaflight is not how loud it is, but the frequency of the tone. Not trying to go in-depth here, mid tones is what the human ear listens to the best. So, I too find that the number 3 is the best frequency. In BLHeli (suite or configurator) the Beacon Strength value I use is 110. I don’t feel quite comfortable going beyond this because, when using this as the lost model alarm, after it beeps for a while (while I’m trying to find my quad), my motors start to get a little hot.

_nd345 16th December 2018 - 11:14 pm

I installed a super loud buzzer and wanted to turn off the dshot beacon. i turn it “off” but the butterflight configurator always comes back on and tone 1. i don’t get the tones, but it annoys me that the switch shows the on position — any idea how to make it show off properly?

Yair Herrera Hernandez 29th October 2018 - 2:20 pm

HI, when NOT armed, can the ESC beeper confirm for example accelerometer calibration? In other words I am wondering if the ESC beeper can work same as the piezo beeper as long as the motors are not armed.

I hear tones at start up (ESC controller start up), I have successfully set beacon to work on AUX switch.. but other than that I never hear any tones coming from my quad., when I had a piezo installed I could hear all sort of sounds, all the beeper alarms (options) are on. Using Betaflight 3.5


Tony Siu 21st October 2018 - 3:52 am

Thanks for your information.
I wish I could still turn the motor of my brush-less quad some how in order to generate noise. So that I still hope to find it.

na 16th October 2018 - 1:37 am

set beeper_dshot_beacon_tone = 0 doesn’t work

Andrés 29th October 2017 - 1:47 am

Is there a way to use the motors as a low voltage beeper? Thanks

Oscar 30th October 2017 - 5:38 pm

no, because when you are flying, motor are spinning and they wouldn’t be able to make sound.

Zsolt 21st June 2017 - 5:54 am

Okay but how can I bind to an aux?

Gbaor 23rd June 2017 - 6:04 am

you cannot. thats the point, when you loose your kvad, after 2 min it will start beeping automatically.

Oscar 25th June 2017 - 4:26 pm

you can’t, yet.
Hopefull that will become a feature in BLHeli_32.

Kevin 6th April 2018 - 7:54 pm

hey Zsolt yes you can just set it up in the modes tab on a aux switch just like you would setup a regular mode. Easy pessy, have mine setup on a aux switch so I dont have to wait for the time limit, it also helps in tall grass when you land and cant see your quad you dont have to wait 2 mins for it to start beeping just flip the switch and oh there it is.

Ian 17th June 2018 - 3:26 pm

What Aux switch though? same as the default buzzer? mines on AUX3 and although my buzzer works it’s very faint (quiet) AUX 3 does not seem to activate my ESC beacon though.