Hi guys,

I've recently decided to try and get Bidirectional DShot working so I can use RPM Filtering to try and get a nice flying feel.

Initially I had issues with my ESCs as they are BLHeli_S G-L-30 and as I was made aware they don't support BDDShot out the box. So I went about flashing with JazzMaverick firmware, however couldn't get it working and BLHeli kept losing track of what firmware I was on etc. I flashed back to standard firmware with BLHeli Suite and then tried JESC after and realised that to my surprise that the licenses weren't required for L type ESCs. So I attempted a flash with it and it worked!

So at this point I now have BDDShot enabled on DShot150 with 8 kHz gyro update and 4 kHz PID loop frequencies. I've checked to see if I get errors on the motors tab and they spin up with 0% errors. All looks good! But it doesn't sound good at all... my motors now seem to be making a crackling / popping noise when armed.

Anyone got any ideas what this is all about? Neither motors or ESC seem to be getting hot although I haven't attempted a flight yet.

Thanks a bunch! 

Well I just had a flight with it and it flew great! Still made a load of noise but flew better than it ever has.

Motors / ESCs weren't hot (or even warm really). Don't know if this is something I should be worried about or not.

you should change your pidloop frequency.
the frequency should match with the speed of the protocol, otherwise you loose chip-performence without a benefit.
you should choose 2k/2k for dshot150/ 4k/4k for dshot300 (f411 chip wont be able to handle this: 8k/8k for dshot600)

to get sure about your fc settup, you can use the command "tasks", will display how hard your fc have to work, probably its in trouble?

(17-Sep-2020, 09:56 AM)hugnosed_bat Wrote: you should change your pidloop frequency.
the frequency should match with the speed of the protocol, otherwise you loose chip-performence without a benefit.
you should choose 2k/2k for dshot150/ 4k/4k for dshot300 (f411 chip wont be able to handle this: 8k/8k for dshot600)

to get sure about your fc settup, you can use the command "tasks", will display how hard your fc have to work, probably its in trouble?

Thanks for that info  I did initially try to save it at 8k/8k but when saved it went back to 8k/4k. I'll have another look. I didn't realise that the frequencies should be relating to what you set DShot to tbh.

When I tried BDDShot300 I was getting a higher error percentage on the motors tab.

Have been running tasks while making changes and max was never over 45% with average sitting around 32%.

other thin i would try is decreasing filtering, set the sliders 1.3, do test hovering, check your motors for heat. this would also increase the performence - aslong as this filtering isnt needed.

(17-Sep-2020, 10:07 AM)hugnosed_bat Wrote: other thin i would try is decreasing filtering, set the sliders 1.3, do test hovering, check your motors for heat. this would also increase the performence - aslong as this filtering isnt needed.

Yeh tbh that was going to be my next stage after I'd got a test flight in with BDDShot enabled. Motors are nice and cool so I'll drop it a little bit to see if it helps. Thanks again

(17-Sep-2020, 10:09 AM)whoelseisbored Wrote: Yeh tbh that was going to be my next stage after I'd got a test flight in with BDDShot enabled. Motors are nice and cool so I'll drop it a little bit to see if it helps. Thanks again

Ok so now... DShot150 with 2k/2k... BDDShot enabled... you can hear the noise in the video below...



I've also tried DShot300 with 4k/4k. Same noise.

Looks to be to do with Bidirectional DShot... just disabled it and the noise is gone completely. Enabled it and it comes back again. Rules out motor bearings etc

Tried bringing down the filters and also hasn't made a difference to the noise.

the relationship between pidloop frequency and esc protocoll is "only" in case of biderectional dshot, rpmfiltering.

i fly a few quads without rpmfilter, rpmfilter isnt that wonder described by many peoples. at least on some of my quads and my way of tuning.
if you disable bidirectional dshot, you can boost back to 8k. i have awsome performing quads without rpm filtering. no reason to get rpm filtering with any downside.

i cant, but probably someone could analyse a blackbox log and point out what cause the noise on biderectional dshot

I had that if I used Jazz Maverick firmware above 16.73. Was informed that betaflight supports them only up to 16.73.