DShot BLHELI_32 ESCs with Pixhawk 4

#1

Hi,

I’m want to connect 4 BLHELI_32 DShot 40A ESCs to a Pixhawk 4 (so using the PM07 power board) to power the motors for a quadcopter. Is this currently supported? I’ve been advised that I can just connect the ESC signal and signal ground wires to the FMU rail. But the FMU rail still outputs PWM, and DShot is digital, so I’m skeptical as to whether this will work. I imagine I’d also need to reconfigure the airframe so that the ESCs are no longer on MAIN1-4? Do I still power the ESCs off of the I/O 1-4 outputs on the Power board?

Any answers to the above would be much appreciated.

Thanks,

Tom

#2

Basically, I’ve found a lot of threads from last year about adding Dshot support, and I was wondering if this has now been done, and if I’ll be able to use my Dshot ESCs with PX4 and a Pixhawk 4?

#3

The board is capable of DShot, but that isn’t supported by PX4.
The esc’s will probably work with pwm or oneshot.

#4

Thanks very much.

So you think I could give them power and signal just off of the MAIN1-8 I/O outputs on the power board? (ie, normal PWM)

If I wanted to use OneShot, would I need to connect the signal wires via the FMU rail, and power from the I/O outputs?

#5

Best to follow the guide to get the connections right.

#6

Yeah I know how to wire up for Standard PWM (as specified in the Pixhawk 4 wiring Quickstart guide for PX4). But it doesn’t say anything about OneShot there. I’m guessing that the wiring for OneShot is the same (as OneShot takes a PWM input) and that I just need to set the PWM_RATE parameter to 0 to indicate I want to use OneShot. But that’s just a guess, and so any confirmation would be great.

(And incidentally, I’ve checked my ESC documentation, and you’re right, they will support basically any protocol, including Standard PWM and OneShot125.)

#7

Were you able to get them to work? I have a set that I would like to use as well and could use some guidance on how to setup the ESC.

#8

Sorry for the late reply. I never tried OneShot in the end, just standard PWM, and had an ESC fire due to not understanding one of the parameters. I’m decided to move over to using ardupilot so that I can run DShot, so won’t be trying Oneshot on PX4.

However, in terms of wiring, I think you need to power the ESCs from the PM07 pads in the same way you would for the standard setup (from the M1-8 B+ and GND pads), but for best performance, connect the signal wires via the FMU rail, and disable the I/O PWM outputs. Then set PWM_RATE to 0.

#9

Thanks, I’ll keep experimenting

#10

I was able to get my set of motors calibrated manually via connection to radio throttle without any issues. So hopefully when I get the entire bird assembled it will work correctly with my PixhHawk Cube. Makerfire 4pcs BLHeli_S 30A ESC OPTO Electronic Speed Controller 3-6S

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