How to set SERVO_BLH_POLES for BDSHOT

ArduCopter Copter 4.3
1

The wiki mentions setting SERVO_BLH_POLES when using serial ESC telemetry.

how many poles
how many poles1006×771 238 KB

I have a feeling the same applies for using BDSHOT - but I don’t have a reference for it in the wiki.

Can someone please confirm that this parameter is necessary with BDSHOT?

Also - this wiki page says that most motors have 14 poles. I’m installing BDSHOT on a quad using the T-MOTOR AIR2616ii motors. I looked at the T-Motor specs for this motor, and it doesn’t mention how many poles it has. Can someone also suggest a way to find out how many poles these motors have?

Many Thanks!

2

It is, otherwise RPM can be wrong and that’s the whole point. T-motor really needs to step up with the data they supply. What did they say when you asked?

Let’s say you didn’t ask. You can count the poles if they are visable. A google search for “brushless motor pole count” will do it.

1 Like
3

Yeah, they are worried about “Exquisite Texture” of the paint but not poles or other electrical data :laughing:

Thankfully someone did their homework and ecalc says 10 poles

1 Like
4

Yep - 10 poles work - I should have though of checking eCalc myself - did anyway since you mentioned it - sure enough!

Things are pretty wacky if you leave it at 14…

Using @Yuri_Rage handy trick, I tested the motors - they seem to work fine, but they have minor fluxuations in their reported rpm values during the test.

test all motors
test all motors1920×1080 201 KB

I had to use my follow my hunches to set the other parameters - maybe it’s in the wiki somewhere - and I’m just to lame to find it.

Would you mind looking over my shoulder to see if I need to set anything else?

bdshot parameters
bdshot parameters1920×1080 187 KB

I really couldn’t have gotten this far without you all - I can’t tell you how much I appreciate it!

5

You got it, there are only 2 parameters.

6

We worked out 14 poles was correct for that motor, judging by the reported ESC RPM and the FFT graphs with show frequency and calculated RPM.