Pixhawk 6C Bdshot and Telemetry Questions

ArduCopter Copter 4.4
,
1

Hello all, I have redesigned my copter to be more sturdy, and I am currently working through the guide posted at How to methodically tune (almost) any multicopter using ArduCopter 4.4.x

I was given some great help during my first go through with Arducopter setup. I was recommended to enable BDSHOT on my blheli_32 ESC and Pixhawk 6C. I have three main questions:

  1. Is the Pixhawk 6C able to do BDSHOT on all FMU outputs now? I have 6 motors, and I want to enable BDSHOT on channels 9-14 (FMU outputs 1-6). Previously I think only four were available.

  2. Does BDSHOT require an extra UART to be used to work? Or is all that is needed is connecting the ESC signal wires to the FMU output?

  3. Would there be any benefit to running a wire from the ESC telemetry port to the autopilot when BDSHOT is being used?

I really want this copter to fly as flawlessly as possible, and I think all 6 motors having BDSHOT could help.

Appreciate the help,
-Peter

2
  1. All 8 Main outputs support Bdshot300 with V4.5.0-Beta2. Look for the BRD_IO_SHOT parameter.
  2. No.
  3. For telemetry data other than RPM.

Pixhawk 6C

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3

Thank you for the clarification! I can live without other telemetry and free up a UART for other things.

  1. I am running the 4.4.4 BDSHOT firmware, in my understanding that only allows BDSHOT on FMU outputs 1-4 correct?

  2. So in order to have BDSHOT on 6 outputs, I should move the cable from FMU Output to I/O Output, update to 4.5.0-Beta2, and use the new BRD_IO_SHOT param to enable it?

  3. Are there any significant changes that I need to make with other parameters, specific to this new firmware?

Thanks again! I realize development is happening all the time with these newer boards, just trying to stay on top of it.

Screenshot 2024-03-04 162447
Screenshot 2024-03-04 162447811×486 35.9 KB

4
  1. Well I didn’t answer that did I? I’m not sure actually if there is a 4 output limit for Bdshot on the AUX outputs of the Pixhawk 6C. I know how to find out though. Configure 6 outputs for Bdshot, run Motor Test and then see if RPM is present for all 6 from the Live Tuning Screen while it’s running.
  2. Yes to how you enable Dshot/Bdshot on the IOMCU outputs. You need to set some other Servo parameters as you typically would.
  3. No, other than Dshot300 is the max you can go. Dhot600 will not work.
5

I apologize for the repetition, just wanted to double-check for my documentation. I just tested as you suggested, and there is in fact a 4 output limit on the 4.4.4 firmware.

I will make certain to use DSHOT300.

Thanks again! My questions are all answered.

6

Clarification:
Dshot300 1-8
BDshot300 1-4

7

All 8 AUX outputs support bdshot on the Pixhawk 6C

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8

Just want to make things completely clear.

@andyp1per , are you saying I should use BDSHOT on the MAIN or AUX port? And I assume that 8 BDSHOT outputs are only available with the Beta2 firmware?

Firmware DSHOT BDSHOT
4.4.4 9-16 AUX, DSHOT300 9-12 AUX, DSHOT300
4.5.0-beta2 1-16 MAIN and AUX, DSHOT 300 9-16 AUX, DSHOT300
9

I got it figured out. I decided to stick with FMU/AUX output based on some short testing.

Firmware DSHOT Support BDSHOT Support
4.4.4 9-16 AUX, DSHOT600 9-12 AUX, DSHOT600
4.5.0-beta2 1-16 MAIN and AUX, DSHOT300 1-4 MAIN, 9-16 AUX, DSHOT300
10

It should be:

Firmware DSHOT Support BDSHOT Support
4.4.4 9-16 AUX, DSHOT600 9-16 AUX, DSHOT600
4.5.0-beta2 1-8 MAIN and 9-16 AUX, DSHOT600 1-4 MAIN, 9-16 AUX, DSHOT600
1 Like