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3Digi FBL System 3Digi Supoort


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Old 01-07-2017, 02:26 PM   #1 (permalink)
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Default 3DIGI Governor w/ Hobbywing Compatibility

I'm having some trouble with 3Digi governor and my Hobbywing 80a V4 esc.

It appears that the rpm output from the esc is dropping out in very small time intervals. What I see in the logs is a bunch of status updates "Gov activated". There's definitely "noise" on the rpm out based on the logs.

This appears to be a compatibility issue. I just removed a Brain from the model to help a fellow pilot with tuning on the Goblin 420 which was working just fine on the external Brain gov.

I've attached the log file. Download and rename as .4DF
I pulled the RPM connection while testing just to see the result in the log. Hence the RPM error.


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Old 01-07-2017, 03:43 PM   #2 (permalink)
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Well I'll just talk to myself...

Apparently HW has an issue. A digital NPN transitor seems to be the fix.

Some interesting posts that I missed before posting. This might be worth a sticky

https://www.helifreak.com/showthread.php?p=7228819

https://www.helifreak.com/showthread.php?t=760472

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Old 01-08-2017, 04:55 AM   #3 (permalink)
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Hi,
thanks for the info and the log file.

The issue of the Vortex and some other FBL systems and the transistor solution was something different. I think they didnīt have a signal at all and used the transistor as an inverter. Thatīs why the 3Digi got the PullUp/PullDown setting.

What you can see in the flight log are small drop outs and spikes of the RPM signal.
If the 3Digi detects such a drop out, if goes in in a kind of hold and waits for a short period of time, if the signal comes back. When it comes back, the governor continues to work and you see the "Governor active" entry in the EventLog.
If the drop out is too long, the governor stops working, logs an "Error RPM sensor" in the EventLog and then starts to route through the transmitter throttle servo signal to the ESC. Thatīs what you see at the end of the log.

Iīm curious about the opto cable results. If you have a flight log using such a cable, please post it here.

This all is again an example, how useful and handy the flight logging of the 3Digi is. Just a short look into the flight data and you can see what happened.
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Old 01-08-2017, 07:55 AM   #4 (permalink)
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Quote:
Originally Posted by DirkS View Post
Hi,
thanks for the info and the log file.

The issue of the Vortex and some other FBL systems and the transistor solution was something different. I think they didnīt have a signal at all and used the transistor as an inverter. Thatīs why the 3Digi got the PullUp/PullDown setting.
How can you tell what the optimal setting is? I know with some sensors it seems to work either way but how do you know which is the correct one?

Another interesting thing I've noticed is that with my YGE ESC the external hobbywing sensor seems to be unstable if the motor PWM is set higher than 8khz.
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Old 01-08-2017, 08:24 AM   #5 (permalink)
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Quote:
Originally Posted by DirkS View Post
Hi,
thanks for the info and the log file.

The issue of the Vortex and some other FBL systems and the transistor solution was something different. I think they didnīt have a signal at all and used the transistor as an inverter. Thatīs why the 3Digi got the PullUp/PullDown setting.

What you can see in the flight log are small drop outs and spikes of the RPM signal.
If the 3Digi detects such a drop out, if goes in in a kind of hold and waits for a short period of time, if the signal comes back. When it comes back, the governor continues to work and you see the "Governor active" entry in the EventLog.
If the drop out is too long, the governor stops working, logs an "Error RPM sensor" in the EventLog and then starts to route through the transmitter throttle servo signal to the ESC. Thatīs what you see at the end of the log.

Iīm curious about the opto cable results. If you have a flight log using such a cable, please post it here.

This all is again an example, how useful and handy the flight logging of the 3Digi is. Just a short look into the flight data and you can see what happened.
I believe the issue has to do more with Hobbywing than any of the fbl builders from what I've read. HW's rpm out doesn't seem to pull down enough (logic voltage 0) for reliable operation, according to Angelos's observations.

I'll have the opto coupler added soon and report my findings. I expect it will work fine since I've had zero issues with the 3Digi governor so far.

Love the logging! Thanks!

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Old 01-08-2017, 08:25 AM   #6 (permalink)
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On a recent episode of RCHN it was discussed how Hobbywing ESCs don't play nice with FBL governors when Active Freewheeling is on. I think this was related more to performance though, but you may still want to look into this after you fix the RPM signal issue.

For fixing the RMP signal issue, look at this:

http://www.rchelination.com/hobbywing-rpm-error-fix/
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Old 01-08-2017, 08:32 AM   #7 (permalink)
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Quote:
Originally Posted by 3Dmuse View Post
On a recent episode of RCHN it was discussed how Hobbywing ESCs don't play nice with FBL governors when Active Freewheeling is on. I think this was related more to performance though, but you may still want to look into this after you fix the RPM signal issue.

For fixing the RMP signal issue, look at this:

http://www.rchelination.com/hobbywing-rpm-error-fix/
Thanks, I discovered that yesterday too. Funny part was I even remember them talking about it in the Podcast. Never registered ;-p

Glad they posted about it. I'll test it out soon and hopefully report success.

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Old 01-08-2017, 04:39 PM   #8 (permalink)
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Default Test with BC337-16 NPN

Well I scavenged up an NPN transistor and wired it in line. Set the 3Digi to Pullup mode since it wouldn't read anything in pulldown. I'm guessing because the transistor is inverting the source signal.

The results are pretty much the same.

I've attached my log file. I'm going to pick up the Scorpion Opto cable to see if that makes any difference. I think they use a PNP circuit so there's a need for power to the coupler.

I've read that Spirit uses a filter that can be tuned in the software to help buffer some of the noise. Could a parameter be added to the governor rpm input to ignore the glitches? Sure to much filter would reduce the governors performance, but as of now, I can't get the governor to work with Hobbywing v4.

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Last edited by Dmaxison; 01-08-2017 at 06:44 PM..
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Old 01-08-2017, 10:07 PM   #9 (permalink)
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Get a short extension and wrap it around a ferrrite toroid and see if that helps. Even if you have enough room on the ESC's RPM lead I'd recommend using the extension to test first so you don't have to undo it if it doesn't help.

Alternatively you could use a clip on ferrite bead.
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Old 01-08-2017, 10:25 PM   #10 (permalink)
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Quote:
Originally Posted by Atomic Skull View Post
Get a short extension and wrap it around a ferrrite toroid and see if that helps. Even if you have enough room on the ESC's RPM lead I'd recommend using the extension to test first so you don't have to undo it if it doesn't help.

Alternatively you could use a clip on ferrite bead.
Thanks, I'll give it a try.
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Old 01-09-2017, 11:26 AM   #11 (permalink)
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Another option would be to use an external RPM sensor. Not great considering that your ESC should do that, but it is what it is I guess.
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Old 01-09-2017, 03:32 PM   #12 (permalink)
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Quote:
Originally Posted by 3Dmuse View Post
Another option would be to use an external RPM sensor. Not great considering that your ESC should do that, but it is what it is I guess.
Sure, that should work. However let me reiterate that the HW rpm is compatible with Brain. Not sure what they're doing to deal with the noise but it worked just fine. So I'm thinking possible software filter.
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Old 01-09-2017, 07:54 PM   #13 (permalink)
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Default Latest test results w/ ferrite ring

So I did some more testing using a ferrite ring. I tested with the ring on either the RPM port or the Throttle port. Same results either way. I also removed the npn transistor said to help with this problem. Here's the latest log...

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Old 01-10-2017, 04:46 AM   #14 (permalink)
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Interesting log. Well, I think I can try to make the gov a little bit less picky and more forgiving in these situations.

You could improve the current situation a little bit, if you increase your throttle input signal. Go up to -400 or -350. About the level, that the throttle output most of the time has has.
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Old 01-10-2017, 06:23 AM   #15 (permalink)
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Quote:
Originally Posted by DirkS View Post
Interesting log. Well, I think I can try to make the gov a little bit less picky and more forgiving in these situations.

You could improve the current situation a little bit, if you increase your throttle input signal. Go up to -400 or -350. About the level, that the throttle output most of the time has has.
I dropped the main gov gain to 20 and lowered my throttle curve due to bench testing with no blades. With a normal V curve as backup, I was getting crazy overspeeds when the gov would drop out and default to the curve. Even through the logs don't indicate the rpm sensor lost, the behavior says otherwise. When I reduced the throttle output I could easily hear the transition from gov mode to curve. I also could see it on my Jlog rpm telemetry.

I still plan on trying the Scorpion opto cable to see if that works. I'll post back soon.
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Old 01-13-2017, 02:01 AM   #16 (permalink)
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Are there some advice for the governor? I installed the hobbywing rpm sensor on the 3digi and did all the setup. I can't read the rpm correctly. I spool up without main and tail blades, could be the problem?
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Old 01-13-2017, 04:25 AM   #17 (permalink)
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Quote:
Originally Posted by andrea_farins View Post
Are there some advice for the governor? I installed the hobbywing rpm sensor on the 3digi and did all the setup. I can't read the rpm correctly. I spool up without main and tail blades, could be the problem?
Are you in pull down mode?
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Old 01-13-2017, 06:47 AM   #18 (permalink)
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Are you in pull down mode?
Yep
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Old 01-13-2017, 09:57 AM   #19 (permalink)
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Post your log so that we can see the rpm input.
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Old 01-14-2017, 09:05 PM   #20 (permalink)
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Quote:
Originally Posted by DirkS View Post

...The issue of the Vortex and some other FBL systems and the transistor solution was something different. I think they didnīt have a signal at all and used the transistor as an inverter. Thatīs why the 3Digi got the PullUp/PullDown setting....
Ok, so I understand a little better now and your right. Doesn't matter if you use the Opto cable or not still see dropouts in the rpm log.

However something must be possible to do besides changing the esc or using an external phase sensor.

Perhaps a longer duration before the unit shifts to the throttle curve? I know you said there's a delay and the event log should report loss of rpm, however my tests tell me otherwise. Gov kicks in and out intermittently making the model impossible to fly safely.

I hate to say it but MSH has it working on the Brain. Since that's what I had on this model previously.

Here's a log of bench testing the RPM input to the 3Digi using Scorpion's opto cable, pull-up mode, HW set with active free wheel off.



Zoomed in to the drop out at 29 sec.

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