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Buzzer Sound is WEIRD on H7 / Matek H743 SLIM / AC 4.1.0-beta5 WITH bidir DSHOT

Since I switched to AC firmware 4.1.0-beta5 WITH bidirectionnal DSHOT support, it seems to me that the BUZZER play its sound in a strange manner : very low volume, and WEIRD freq in beeps…

Does anyone hase the same issue ?

There is no issue with AC 4.1 firmware without bdshot , neither with betaflight 4.2.8 …

The timer required by the buzzer is also required by bi-directional dshot - you can’t have both I’m afraid. So with bi-directional dshot you get the simpler on/off buzzer

Thanks for this reply,

well, i was hoping h7 mcu not to have such limitation… Do you have any source code pointer for reference ?

do you mean i should switch to an active buzzer instead the passive one installed ?

I cannot find any reference of this limitation in the documentation…

It’s not really anything to do with h7 or f4 etc, it’s all down to which pins the manufacturer has used for which functions. Even on h7 all pins have a limited number of functions that they can carry out. On the Matek board there are so many motor outputs that it would be possible to reconfigure the hardware definition to do motor outputs 1-4 on S5-S8, say which might then free up the timer the buzzer needs. You would need to look in libraries/AP_HAL_ChibiOS/hwdef for the hardware definition for your board.

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Well, understood ! so it is kind of matek fault …

Thanks again for the detailed answers…

Hello everyone.
I’m having trouble with a buzzer.

I’m trying to make a small copter using FC: MAMBA Basic F405 MINI MK3.5. I modified hwdef.dat of MambaF405US-I2C a little and uploaded to FC. It works expected except for no buzzer sound, it works as expected. This FC has a buzzer assigned to PC13 (without timer function). If I use an active buzzer (which doesn’t require PWM switching), I feel like it can be used with PC13 that doesn’t have a timer function, but I don’t know what to do. Is there any way? Or does a buzzer need a timer function?

You can get an on/off sound just no actual tunes. Have a look at the BeastH7 for an example.

Thank you for your reply.

With reference to BeastH7 I wrote hwdef.dat as follows.
define HAL_BUZZER_PIN 80
define HAL_BUZZER_ON 1

I set the parameters that seem to be related to an active buzzer as follows.
NTF_BUZZ_ON_LVL, 1 (I also tried 0,1)
NTF_BUZZ_TYPES, 0 (I also tried 0,1,2)
NTF_BUZZ_VOLUME, 100 (I also tried 0,50,100)

In addition, I also tried following to make “LostCopterSound” sound by ch7 of RC.

But my active buzzer doesn’t make any sound.
Is there anything I have forgotten?
Is it possible to sound an active buzzer on port PC13 that does not have a timer function?

Of course, if I upload Betaflight firmware to FC, an active buzzer will beep on PC13 without any problems.

I would appreciate any additional information.

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