How can you use the series of beeps you hear when powering up to diagnose issues with your equipment? Should all of the beeps be synchronized or is it ok if they are slightly off? Are there different patterns you might hear and if so, what do they all mean?

  • 1
    $\begingroup$ This will depend on your speed controller(s), so the question is a bit broad at the moment - do you have a specific model in mind to narrow down the scope? $\endgroup$
    – Kralc
    Commented May 4, 2020 at 14:39
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    $\begingroup$ I currently use a Holybro Tekko32 F3 40A 4-in-1 ESC but it seems like all the ESC's that I have used so far ( either 4 singles or 4in1s ) have all had the same series of beeps. At least in quadcopters. $\endgroup$
    – 5zero7rc
    Commented May 4, 2020 at 14:43
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    $\begingroup$ what does the user manual say about the beeps? $\endgroup$
    – jsotola
    Commented May 4, 2020 at 15:43

2 Answers 2


So normal startup sequence is three short beeps followed by two long beeps with different tonality.

  • First three beeps means that ESC is powered and activated.
  • Then if the throttle signal is detect goes one long low tone beep.
  • Then if throttle is zero goes one long high tone beep. This signal means the end of the start sequence and ESC is ready to run.

Here is diagram of normal boot sequence beeps: enter image description here

There are manuals for both BlHeli_S and BlHeli_32 and they have a sections about sound sequences and what they mean.

Regarding the slight de-sync of startup tones it looks like this is not a problem and just something to do with Betaflight boot process and happens only with Bi-directional DShot enabled: https://github.com/betaflight/betaflight/issues/9103

Most likely this is caused by:

Some ESC's first entering boot mode because the signal line from the FC is not readily booted and doesn't provide stable signal level before the ESC is booting.

And it can be "fixed" if you first power-on the Flight Controller and then the ESCs: https://github.com/betaflight/betaflight/issues/9103#issuecomment-546684302


The normal blheli startup tones are similar to beep beep beep... boop. boop

The first 3 beeps are the ESC's powering on and initializing then there's a pause followed by two more beeps which means the throttle signal has been received.



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