Replies to This Discussion

Permalink Reply by 13brv3 on March 2, 2010 at 10:28pm

Hi Pete,

I'm not sure what 4 pin connector your referring to, but for something expendable like a connector, just cut the pins, and remove them one at a time. That's what I'd do with the gyros where possible. Solder wick, dipped in flux paste removes the solder pretty easily.

If you're working with something that requires multiple pins to be heated at once, a hot air rework station is the way to go. With solder paste, and a hot air station, even changing the CPU isn't all that hard to do.

Rusty

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Permalink Reply by chris eldred on March 7, 2010 at 5:20am

Can anyone suggest a fix for this, I was running matrixpilot 2.02 and had to modify the options.file to work with 3 channels, elevator, rudder, throttle. All worked fine, then I edited the options file as I had left ailerons still enabled and now the ESC is telling me there is an abnormal servo input. It works absolutely fine straight from the Rx. I have the channel reversed on the Tx and have tried the software reversal in options.h but I am getting nowhere. My next step was to 'scope the o/p on ch3 from the UDB.

Any suggestions welcomed, the option file is attached

regards

chris

Attachments:

• options.h, 12 KB

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Permalink Reply by William Premerlani on March 7, 2010 at 5:43am

Hi Chris,

There is a quick way to find out what channel 3 output from the UDB is doing: connect a servo up to it, and power your receiver by plugging your ESC into a spare channel. Check to see how the servo responds to the Tx through the UDB. Then, connect a servo up to channel 3 of your Tx to see what the correct polarity is supposed to be.

Chances are you will find that either there are no pulses coming out on channel 3 (cold solder joint), or the polarity is reversed.

I note in your options.h file that you have the UDB polarity of the throttle hardcoded to 0. I assume you also tried 1?

A couple of other possibilities (long shots):

1. ESC not making good connection to UDB.

2. You have to satisfy both the ESC's and UDB's ESC arming sequence during power up. The way this is normally done is to power up your Tx first, and power up the UDB. Then, if there is an arming sequence for the ESC, you need to do it either as soon as the UDB powers up, or wait until the UDB records the trim settings, which it does at around 10 seconds after power up, indicated by a single "wag".

Let me know what you find out when you connect up a servo to channel 3 of the UDB, we'll then go from there.

Best regards,
Bill

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Permalink Reply by chris eldred on March 7, 2010 at 6:04am

Hi Bill

excellent suggestion, I was getting a bit despondent, tried the servo swap ESC does the samething in ch 2, and ch3 seems to work the elevator servo fine, so the output seems good.

I tried both 0 and 1 for the throttle hardcode.The ESC (turnigy plush 40A) works ok direct to the Tx, it just wants to see the thottle at minimum setting.

I'll try and find another ESC to test with

Any other suggestions would be great

regards

Chris

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Permalink Reply by Riccardo Kuebler on March 7, 2010 at 6:12am

Chris,

I noticed that you disabled roll stabilization.
I guess this has to be enabled to have roll stabilization, even if controlled by rudder.

Btw, why did you reverse throttle channel ?

Cheers,

Ric

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Permalink Reply by chris eldred on March 7, 2010 at 6:43am

Hi Ric

the roll stab off was shown in a number of option.h files i have looked at, I thought that was the way to go, but I am open to any ideas.

the thottle reverse is needed on my futabu to have min throttle with the left hand stick all the way down

regards

Cris

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Permalink Reply by William Premerlani on March 7, 2010 at 7:32am

Hi Chris,

Trying another ESC is a good idea.

Also, there is one more thing you could try that might give us a clue....

You mentioned that everything was ok when you first started out.

Save a copy of your options.h file, and then download a fresh copy of MatrixPilot, and see if your throttle works then. If it does, then we can take a closer look at the implications of the changes that you made to options.h. If that does not work, then we will want to take a closer look at the possibility that your ESC does not make a good connection to the UDB.

By the way, you might want to join the uavdevboard discussion group. There are around 100 members, and there are always several lively discussions going on.

Best regards,
Bill

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Permalink Reply by 13brv3 on March 7, 2010 at 7:33am

Hi Chris,

I use the Turnigy Plush ESCs (18A and 30A) with the UDB, so I know they will work OK. You might be on the very edge of the throttle range.

When the ESC doesn't arm, are you getting a constant beep-beep-beep-beep... from the motor? If so, you might try setting the range. For the Turnigy Plush, you set the throttle to full, turn on the power, and expect to hear two beeps from the motor. At that point, lower the throttle to minimum, and you should get the normal start up beeps.

Good luck,
Rusty

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Permalink Reply by chris eldred on March 7, 2010 at 8:11am

Rusty

thanks for that, seems the UDB must have a slight difference in pulse output, recal'd the ESC and it seems to work odd it worked fine direct from the Rx.


Bill thanks for the tip on the servo swap, I feel a bit stupid not trying that first

I'll have to re edit the options.h now as the throttle goes full on in stabilise, need to edit the throttle output reversing bit

regards and thanks

Chris

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Permalink Reply by 13brv3 on March 7, 2010 at 8:41am

Hi Chris,

Glad that worked. The UDB outputs pulses at a slower rate than the receiver does, so maybe the ESC takes that into consideration somehow. You'd really have to put a scope on the throttle signal going to the ESC to see what's different about the two.

As for the full throttle in stabilized mode, I'm betting you have altitude hold enabled. The normal behavior for the UDB is to go to full throttle to climb to altitude, so that's probably what you're seeing. If the throttle is nearly closed, the motor should stay off, but if you open it slightly, it will go to full throttle until it can climb to the desired altitude.

Cheers,
Rusty (being soundly thrashed by Eagle CAD)

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Permalink Reply by William Premerlani on March 7, 2010 at 8:56am

Hi Rusty,

The UDB output pulses are at 40 Hz. That is a legacy from my initial work 6 years ago based on some testing that I did. At the time, I had fried a few servos by trying to run them at high pulse rates. I did some testing, and backed off from the point where the H bridge in the servoe shorts out, which actually is pretty close to 50 Hz. I did not realize that most Tx's generate pulses at 50 Hz. Most servos and ESCs will work fine at 40 Hz. I suppose we should raise the pulse rate to 50 Hz, it would not be that hard to do. I'll put it on my "list".

I hope that you get the upper hand with Eagle CAD. ;-)

Bill

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Permalink Reply by William Premerlani on March 7, 2010 at 8:44am

Hi Chris,
The behavior of the throttle in stablized mode will depend on what options you select. There is an option to apply altitude hold in stabilized mode. If you pick that one, the throttle will kick way on when you switch to stablized mode on the ground, because the controls are trying to reach altitude.
For your first few flights, I suggest that you turn altitude hold off, until you get the feel for how stabilized mode works, and you get the gains set the way that you want. In fact, if you are not using altitude hold, you can connect your ESC directly to the Rx.
Best regards,
Bill

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