Really weird ESC arming problem, please help! NOW SOLVED!

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Really weird ESC arming problem, please help! NOW SOLVED!

Postby hogster » Wed May 14, 2014 8:44 pm

Hi all :)

I think I'm eligible for the 'who's got the most stubborn platform' award :(

I went out to do a test flight with my X8, my new set of ESCs (all properly calibrated, and not being powered by 5V when they didn't need to be :roll:) but now I have my next problem.

On applying power to the ESCs and AQ, the ESCs make their start-up chime (three ascending beeps) ... and then they just sit there indefinitely. No amount of arming / disarming the AQ (with the rudder stick), or throttling up and down gets the ESCs to arm.


Here's what I do know:

– If the AQ and ESCs are connected to a bench power supply (set to 25V, 2A current limit), when the PSU is switched on, the ESCs make their start-up chime, and then emit a beep every second until I arm the AQ. They then all arm simultaneously – this happens every time I turn on the PSU.

– As soon as I swap to the main battery, the ESCs make their start-up chime, but then refuse to make their 1-beep-per-second "I'm waiting for good PWM" noise, and they refuse to arm.


This is where it gets more confusing :?

- If I connect one of the ESC signal plugs (just signal and ground) to a battery-powered servo tester set to output 1000µs, and then connect the ESCs and AQ to the flight battery, the ESC connected to the servo tester arms correctly, whilst the remaining 7 ESCs stay quiet. :?:


What is the difference between powering up the ESCs and AQ with a flight battery vs. with a bench PSU, and why does using a servo tester get around the problem? Does the AQ output good PWM a moment earlier when using the PSU?

I'm really puzzled (and slightly annoyed) by this one, and any input is most grateful received – I want to get this thing flying! :(

Many thanks, David :)
Last edited by hogster on Fri Jul 11, 2014 10:59 am, edited 3 times in total.
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Re: Really weird ESC arming problem, please help!

Postby chschmid » Wed May 14, 2014 9:19 pm

What values for arm did you set for your AQ?

It seems that Arm PWM is to low. Make it 1000 or 1005 and try again.

Cheers
Christof
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Re: Really weird ESC arming problem, please help!

Postby hogster » Wed May 14, 2014 10:22 pm

Hi Christof,

As per this thread:

viewtopic.php?f=27&t=3254

My ARM PWM is set to 1000µs, starting is set to 1050µs and max is 1950µs.

I will try raising the ARM PWM value tomorrow and trying again ...

Many thanks :) David
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Re: Really weird ESC arming problem, please help!

Postby hogster » Thu May 15, 2014 10:31 pm

I just changed it to 1025us with no difference :(

Interestingly if I have the PSU output on but with the male XT60 connector disconnected from the vehicle, on connecting the PSU to the vehicle (as you would a battery), the ESCs refuse to arm after making their start-up chime. So using the PSU doesn't guarantee the ESCs will arm correctly.

It has to be something to do with the initial surge of current upsetting the AQ outputs (or the ESC inputs).

I'm completely baffled by this, and my X8 and AQ will remain grounded until I can solve it :(

Many thanks for any and all suggestions,

David
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Re: Really weird ESC arming problem, please help!

Postby chschmid » Thu May 15, 2014 10:47 pm

Ok, so ist not the PWM thats to low as I thought.

1. What about the low voltage protection of the escs. Maybe they have one and is set to low.

2. What about a bad solder Joint of the main line. At Connection time the tremendous surge of many hundred amps of your caps will shut the voltage down until the caps are filled if you have a "resister solder joint". I have seen this before. What about connecting, then disconnect for a fraction of a sec and reconnect. Do they arm now?

BTW normally the ESCs arm when the AQ is armed. When the AQ is not armed, there is no PWM Output.
If you connect one ESC to the batt, wait for 10 secs and then connect the Tester, does it arm?

Cheers
Christof
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Re: Really weird ESC arming problem, please help!

Postby hogster » Thu May 15, 2014 11:05 pm

Hi Christof, many thanks for your help :)

I will try your ideas tomorrow / in the next few days and report back. In the mean time, I've just thought of a possible way around the problem.

It's not so much the ESCs not arming which is the problem - as you said, the ESCs don't even get PWM when the AQ is not armed, ie. on boot-up. The problem is the ESCs are not detecting the lack of PWM correctly on boot-up, and not entering their 1-beep-per-second mode which says they're waiting for good PWM.

My possible way around the problem would be to leave the AQ unpowered after plugging in the battery, and then plugging the AQ in a second or two later. That should definitely ensure the ESCs see no PWM and so go into their 1Hz beep mode. I will test this when I have the chance and report back.

Many thanks :) David
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Re: Really weird ESC arming problem, please help!

Postby Trnquill » Fri May 16, 2014 6:59 am

I had weird issues after powering up when I had long power wires to ESCs and thus had to use huge banks of caps. The hex would randomly try to flip upon lift off, just like the motor configuration was messed up in AQ or something. All the motors spun up, but the hex was totally uncontrollable and tried to flip as soon as I applied some power. The problem went away when I moved the ESCs really close to battery and ditched almost all the caps. I don't KNOW if the reason was too big a connection spark and induced current, but it seems like it. So, you could try eliminating the spark by using a resistor inline with the battery/PSU before actually connecting the line fully.
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Re: Really weird ESC arming problem, please help!

Postby hogster » Fri May 16, 2014 10:24 am

Hi Trnquill,

My ESCs are very close to the power distribution board (<5cm) so I'm not sure that could be causing the problem. I will try the resistor in-line trick to see if that cures it.

I've just tried leaving the AQ off whilst powering up the ESCs using the flight battery ... and it didn't solve the problem :shock:

So that rather squarely points to the ESCs being the problem rather than the AQ? That being said, if I have one of the ESCs connected to the servo tester (set to 1000µs), leave the AQ disconnected, and then connect the flight battery to the ESCs, the ESC connected to the servo tester arms correctly every time.

What to do ... :(

I will try the resistor trick next when I have a moment.

Any other thoughts in the mean time would be very much appreciated.

Many thanks, David
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Re: Really weird ESC arming problem, please help!

Postby Trnquill » Fri May 16, 2014 10:58 am

So the ESCs arm when they have valid PWM when connectin power? How about first powering AQ, then then ESCs? This would ensure AQ is outputting valid PWM before you apply power to the ESCs. AQ takes some time to boot up.
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Re: Really weird ESC arming problem, please help!

Postby hogster » Fri May 16, 2014 10:21 pm

Well I'm pleased to say powering the ESCs first and then powering up the AQ allowed me to complete my first flight! Woohoo! :D

Unfortunately it was nearly uncontrollable and my ACC readings were around +/- 5 and sometimes +/- 10 :( There's some serious vibration on there that I need to somehow isolate ...

Trnquill - That's right, they arm fine (even when powering up from the flight pack) if they immediately see good 1000µs PWM. Your suggestion would be the preferable option yes, but unfortunately not the easiest in practice. All the ESCs and AQ are connected in parallel via a power distribution board, and the only way I can break the power to the AQ is I have an in-line connector to allow me to power the AQ on its own when I'm doing firmware updates on the bench. Currently there's no easy way to power up the AQ first, and then the ESCs, when using the flight battery.

Now onto the next problem - the insane levels of vibration :(

Thanks! David :)
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