<p>From what I can tell, this occurrence sounds like something causes the flight controller to reset after a second or so, triggering it to reconnect with the ESCs as it initializes itself again.</p>
<hr />
<p>The <em>&quot;du-du-du beep-beep&quot;</em> noises you point out are generated by the ESC (<em>through the movement of the motors</em>) to signify that they're receiving control inputs from the FC and are ready to go. More specifically, I believe that the <em>&quot;du-du-du&quot;</em> sounds (<em>with ascending pitch</em>) signal that the ESC is receiving signal pulses from the FC and the <em>&quot;beep-beep&quot;</em> sounds mean that the ESC is done with its own initialization process and ready to fly. (<em>some ESCs also use the number of these pulses to indicate the number of cells in the battery they think they're connected to</em>)</p>
<p>If the ESCs are detecting that the FC connects and then reconnects to them after a second or so, this likely means that something on the FC caused it to hard reset and reinitialize itself. This could be caused by anything from broken solder connections on the board to a voltage regulator that finally kicked the bucket. (<em>or has begun to</em>)</p>
<p>With respect to troubleshooting the issue and verifying that the issue is with the FC and not something else, diagnoses aren't very clear cut because the symptoms can vary from undetectable to glaring. Some dead giveaways are:</p>
<ul>
<li>Something on the FC is getting abnormally hot</li>
<li>There are solder connections on the FC board which are visibly broken/intermittent</li>
<li>As you say, a particularly hard crash can kill/degrade FCs</li>
<li>Something just looks off with the FC during startup</li>
</ul>
<p>As @Kralc helpfully mentions: (<em>slightly paraphrased from original comment</em>)</p>
<blockquote>
<p>it can help to try unplugging parts to see if the problem changes or goes away. <em>(Remember, it might also be a combination of parts that cause the issue, so it is good to keep notes of what you've tried)</em> If the symptoms remain even with nothing else connected, it is more likely to be the FC.</p>
</blockquote>
<p>Other symptoms are far more subtle and might not be reliably detectible by the eye. If you are able, I'd recommend trying to replace the FC if none of the above symptoms are present.</p>

CC BY-SA 4.0
2020-11-03T21:56:22.070Z
For the troubleshooting, it can help to try unplugging parts to see if the problem changes or goes away. (Remember, it might also be a combination of parts that cause the issue, so it is good to keep notes of what you've tried.) If the symptoms don't change even with nothing else connected, it is more likely to be the FC.
Kralc
CC BY-SA 4.0
2020-11-03T22:41:36.223Z
I ordered a replacement AIO FC/ESC. I noticed that BLHeli isn't showing one of the motor outputs either. Something very wonky going on. It still flies straight, though...
Tilman Koester
CC BY-SA 4.0
2020-11-05T21:08:24.880Z
Same issue with the new AIO board (crazybee f4). I noticed, it does that when I enable bidirectional DSHOT. And it also doesn't do it if I connect to USB and then battery. It used to not to do that... the only parts I transferred over were motors and batteries. I'll try different batteries next. Maybe these went bad..? Motors are completely resoldered with new connectors, too.
Tilman Koester
CC BY-SA 4.0
2020-11-05T21:09:42.907Z
Found an open issue on github with similar pattern: https://github.com/betaflight/betaflight/issues/9103
Tilman Koester
CC BY-SA 4.0
2020-11-05T21:31:22.550Z
Are your ESCs BLHeli32?
ifconfig
CC BY-SA 4.0
2020-11-05T22:20:31.150Z
BLHeliS. And happens with both JESC and JazzMaverick firmware
Tilman Koester
CC BY-SA 4.0
2020-11-05T22:44:04.763Z
Hrm, well I do know that stock BLHeli_S is incompatible with Bidirectional DSHOT. I don't know anything about its support with JESC and JazzMaverick.

This may be a "simple" bidirectional DSHOT incompatibility issue.
ifconfig
CC BY-SA 4.0
2022-09-03T04:16:21.763Z
FWIW, seeing this same thing on a T-motor ESC+FC. Brand new FC, same behavior. Although when I unplug the FC, I only get one set of beeps. Tried new capacitor, new wires. Looks like a faulty ESC.
user
CC BY-SA 4.0
2020-11-03T18:15:52.570Z
2020-11-03T22:44:54.793Z
2020-11-03T22:44:54.793Z
ifconfig
<p>Just recently, my power-up beep sounds have changed. The normal sequence is just du-du-du beep-beep for ESC power, then throttle signal, right?</p>
<p>Now I get du-du-du, pause, du-du-du (again) beep-beep.</p>
<p>What could this be indicative of? This is an NBD BeeBrain BL AIO FC/ESC running BF4.1 and JazzMaverick 16.77 48k.</p>
<p>This changed without any change in config or setup.
I might have crashed it a bit harder than usual?</p>

CC BY-SA 4.0
2020-11-03T18:05:06.670Z
Hrm. This sounds like the FC briefly browns out or resets during the startup process. Maybe this is an issue with some part of the FC?
ifconfig
CC BY-SA 4.0
2020-11-03T18:09:24.017Z
what do you think would be the best way to confirm if it's FC? .. also, it's ALWAYS dududu twice, never three times, or once if i get lucky.
Tilman Koester
<betaflight><flight-controller><esc><blheli>
ESC power up beeps sound twice: du-du-du...du-du-du beep-beep
Tilman Koester
# ESC power up beeps sound twice: du-du-du...du-du-du beep-beep

(Asked by: username_0 on 2020-11-03)

Just recently, my power-up beep sounds have changed. The normal sequence is just du-du-du beep-beep for ESC power, then throttle signal, right?

Now I get du-du-du, pause, du-du-du (again) beep-beep.

What could this be indicative of? This is an NBD BeeBrain BL AIO FC/ESC running BF4.1 and JazzMaverick 16.77 48k.

This changed without any change in config or setup.
I might have crashed it a bit harder than usual?

**Tags:** betaflight, flight-controller, esc, blheli

> **Comments:**
> **username_1**: Hrm. This sounds like the FC briefly browns out or resets during the startup process. Maybe this is an issue with some part of the FC?  
> **username_0**: what do you think would be the best way to confirm if it's FC? .. also, it's ALWAYS dududu twice, never three times, or once if i get lucky.  

---

## 1 answers

### Answer by username_1 on 2020-11-03. Score: 2 | Accepted answer

From what I can tell, this occurrence sounds like something causes the flight controller to reset after a second or so, triggering it to reconnect with the ESCs as it initializes itself again.

---

The *"du-du-du beep-beep"* noises you point out are generated by the ESC (*through the movement of the motors*) to signify that they're receiving control inputs from the FC and are ready to go. More specifically, I believe that the *"du-du-du"* sounds (*with ascending pitch*) signal that the ESC is receiving signal pulses from the FC and the *"beep-beep"* sounds mean that the ESC is done with its own initialization process and ready to fly. (*some ESCs also use the number of these pulses to indicate the number of cells in the battery they think they're connected to*)

If the ESCs are detecting that the FC connects and then reconnects to them after a second or so, this likely means that something on the FC caused it to hard reset and reinitialize itself. This could be caused by anything from broken solder connections on the board to a voltage regulator that finally kicked the bucket. (*or has begun to*)

With respect to troubleshooting the issue and verifying that the issue is with the FC and not something else, diagnoses aren't very clear cut because the symptoms can vary from undetectable to glaring. Some dead giveaways are:

* Something on the FC is getting abnormally hot
* There are solder connections on the FC board which are visibly broken/intermittent
* As you say, a particularly hard crash can kill/degrade FCs
* Something just looks off with the FC during startup

As @username_2 helpfully mentions: (*slightly paraphrased from original comment*)

> it can help to try unplugging parts to see if the problem changes or goes away. *(Remember, it might also be a combination of parts that cause the issue, so it is good to keep notes of what you've tried)* If the symptoms remain even with nothing else connected, it is more likely to be the FC.

Other symptoms are far more subtle and might not be reliably detectible by the eye. If you are able, I'd recommend trying to replace the FC if none of the above symptoms are present.

> **Comments:**
> **username_2**: For the troubleshooting, it can help to try unplugging parts to see if the problem changes or goes away. (Remember, it might also be a combination of parts that cause the issue, so it is good to keep notes of what you've tried.) If the symptoms don't change even with nothing else connected, it is more likely to be the FC.  
> **username_0**: I ordered a replacement AIO FC/ESC. I noticed that BLHeli isn't showing one of the motor outputs either. Something very wonky going on. It still flies straight, though...  
> **username_0**: Same issue with the new AIO board (crazybee f4). I noticed, it does that when I enable bidirectional DSHOT. And it also doesn't do it if I connect to USB and then battery. It used to not to do that... the only parts I transferred over were motors and batteries. I'll try different batteries next. Maybe these went bad..? Motors are completely resoldered with new connectors, too.  
> **username_0**: Found an open issue on github with similar pattern: https://github.com/betaflight/betaflight/issues/9103  
> **username_1**: Are your ESCs BLHeli32?  
> **username_0**: BLHeliS. And happens with both JESC and JazzMaverick firmware  
> **username_1**: Hrm, well I do know that stock BLHeli_S is incompatible with Bidirectional DSHOT. I don't know anything about its support with JESC and JazzMaverick.  This may be a "simple" bidirectional DSHOT incompatibility issue.  
> **username_3**: FWIW, seeing this same thing on a T-motor ESC+FC. Brand new FC, same behavior. Although when I unplug the FC, I only get one set of beeps. Tried new capacitor, new wires. Looks like a faulty ESC.  

---

