BiCopter + F3FC + Betaflight

[Cshep70]

It’s almost as if something upstream is pointing MOTOR2’s output to a different resource and the ESC is getting the wrong signal.

Edit: (Thanks jihlein). It’s almost as if something upstream is pointing MOTOR2’s output to the right resource but the ESC is getting the wrong signal protocol.

[Frederoo]

Can you verify in the CLI that any of the other resources (not motor or servo) are not mapped to A04?

[jihlein]

Cshep70 – Do I understand correctly that you were able to program BOTH ESCs with your current wiring configuration and resource mapping?

If that is the case, it’s really odd both motors don’t run correctly. Try this for grins, change the ESC protocol to OneShot and try that. Apologies if that’s what your already running, as from your scope trace description it sounds as if you’ve got one of the DSHOT protocols selected.

[Cshep70]

Frederoo,
resource A04 is not called out by any other device. I did have to release ESCSERIAL from A08 in order to assign SERVO2, but the servos seem to be working fine.

jihlein,
good thought. I’ll try that tonight and scope it if unsuccessful. I *was* able to upgrade the blheli firmware in FC-Passthrough to BOTH ESCs. It may not be so odd if the resource is properly assigned so the passthrough works, but the F3FC is not sending the right signal to the resource address.

[jihlein]

I would think that means the resource mapping is correct, otherwise how would it know where to find the ESCs for the BL Heli connection? I’m wondering if there is a DMA issue where certain outputs on the F3Fc in BetaFlight can’t be dshot, hence the suggestion to try oneshot.

Interesting……

[Frederoo]

As far as I recall ESC from the BiCopter kit from David are DShot1200 capable – I use them myself. I don’t recall you could mix modes for motors in BetaFlight (unlike dRonin), so if you are set to DShot, every motor should get DShot. That’s strange stuff happening that I can’t think of a reason for… :/

[jihlein]

The ESCs are capable, I’m not sure the F3Fc is. At least I can’t verify that from the code yet….

[Frederoo]

Ok, I took my BiCopter apart to connect the USB cable – I can set motors to DShot 1200 no problem (it did not revert to PWM after switching tabs), they also work in the Motors tab. Curiously, I had them set to OneShot125 – probably per David’s video.

Some sanity checks, don’t be mad at me if you did those: do both ESCs play init sounds with motors when connected to power? Is their configuration in sync as per this guide https://oscarliang.com/best-blheli-32-settings/ ? I mean are they both set to same values, not necessarily the exact values from the guide – mine were out of sync, hence my earlier problems.

[Cshep70]

had them set to OneShot125 – probably per Davids video: I’m going to try this tonight.

do both ESCs play init sounds with motors when connected to power? : only stuck my ear up to each, but seemingly yes. I will double check by holding them separately and separate from the boom so the vibrations don’t transfer.

Is their configuration in sync as per : I will double check tonight. Thank you.

[jihlein]

Looking at the BetaFlight source/header files, and the STM32F3 reference manual, leads me to believe that the PA4 (TIM3-CH2) resource can not support dshot as coded in BetaFlight, but it should work with oneshot.

Thinking it over, I’m not 100% sure it will work in dRonin either. dRonin may have implemented dshot differently on the F3 (bit banging it, not using DMA) so it may work. I’ve only recently started using dshot capable ESCs with the KakuteF4V2 board, I’ve not tried them with the F3Fc.

I’m betting oneshot makes it work, but if you are really set on dshot, I think swapping motor and servo outputs will make that work, although I’ve obviously not tested that wiring configuration.

[jihlein]

A little bench testing with the logic analyzer and F3Fc:

With my dRonin build, I can get DSHOT600 to work on outputs 1/2/3/4. Wasn’t smart enough to test 5/6 while I was at it. Didn’t look at other DSHOT speeds.

I built a fresh binary of Betaflight 3.5.3. I can’t get DSHOTXXX to work on any channels, but oneshot does work on outputs 1/2/3/4. Again I did not check outputs 5/6.

This seems to contradict some of what’s been seen here, but maybe it’s something to do with BetaFlight 3.5.3, or maybe I’ve set something up wrong. But I would assume that if I can get oneshot to work in the test mode, simply changing the esc protocol to DSBOTXXX should also work.

[Cshep70]

jihlein,
In OneShot the arming tones wouldn’t complete. I would get 1-2-3,4,,, then no 5. Also no motor spinnyspinny.

In MultiShot, I got full tones and yes motor spinnyspinny so, SUCCESS! I have nothing against Multishot I guess 🙂

If you hadn’t been able to put the 2+2 together on the protocol I would probably be taking another no-bicopter-sabbatical. Excellent catch. Thank You.

Frederoo,
My ESCs are sync’d. Thank you as well. In a few more days I should have some flight video but tonight I’m tired and bedding down early.

[jihlein]

If MultiShot works, I’ll bet OneShot works too, likely a small adjustment to the min throttle and/or esc calibration is necessary.

But if it’s working, I wouldn’t mess with it. Good luck with it!

[jstremmler]

Just want to mention that with my Omnibus F4 Pro, Betaflight 4.0, motors connected to output 1 and 2 and servos connected to output 3 and 4, Blheli_32 ESCs Dshot1200 works 100%.

[Cshep70]

Finally a break and a chance to start back.

First @jihlein: With your build, the right motor spinns without the system being armed, just powered on. The ESCs are calibrated. It seems to spin about where a signal level of 1020-1025 might be.

Second: @litterbug:. The sOAT system seems well made, but with the stock motors the props don’t clear the servos. I’m going to use a 2-3mm thick nylon washer to shim the props.

Hopefully maiden soon. We had to rescue 2 of our grandbabies from their opiate addicted parents the week before Christmas. It’s been hectic…

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