Headtracker not working

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Elmardus
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Headtracker not working

Post by Elmardus »

I have a problem with trying to get my headtracker to work. I have the Skylark (Sky eye) headtracker. I use the Turnigy 9XR.
In my mixers I have set 2 channels with PPM6 and PPM7 as source. I have set ch6 and ch7 as output channels in my headtracker.

I can't get any output on my channels. I don't know if the headtracker even outputs a signal....

Does anybody know how to solve this?

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Kilrah
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Re: Headtracker not working

Post by Kilrah »

Do you have access to an oscilloscope?
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Re: Headtracker not working

Post by Elmardus »

Sort of. I have made one that I can plug in to my phone in the microphone jack. I could see a PPM signal, but I don't know how that works...
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Re: Headtracker not working

Post by Elmardus »

I have tested some more. The PPM input of my Turnigy 9XR is not broken, it works if I use it with the DX6i as slave. But when I plug in the headtracker all PPM channels are just zero...
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Re: Headtracker not working

Post by Elmardus »

I have solved the problem!!
There is a mistake in the Turnigy 9XR. In the Futaba port the PPM input is not connected, but in the JR port it IS connected. I solved the problem by connecting the PPM in and out together in the trainer port. I have a schematic if someone wants to see it.

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Crucial
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Re: Headtracker not working

Post by Crucial »

Interesting. On my 9xr both trainer ports output a signal just fine to my 9x.
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Re: Headtracker not working

Post by Elmardus »

That's not what I ment, if you read carefully. I said the INPUT, is not connected, so the trainer output works just fine, but when I try to use it with a headtracker, the input isn't connected, so the headtracker won't work.
With the JR plug the input and output are on the same "pin", but futaba has different pins.
If you connect the input and output together with a wire in the transmitter, the TX will automatically switch between input and output of PPM, depending on slave/master mode I think.
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Crucial
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Re: Headtracker not working

Post by Crucial »

I also answered this in the 9xrforums thread. I think the problem in my testing is that I was using a cable that has a futaba plug on one end and a JR on the other. This is why input and output works in my testing. If I were to use a futaba <-> futaba cable it would be the same as you describe.

I wonder then if you plug in a futaba cable does the radio then turn on without the main power switch being on? This would explain why mine wasn't turning on by itself with my trainer cable. There was no trigger wire in my cable.

I still maintain that there is an issue with PPMSIM not working as it should as that was broken with the JR plug as well.
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Kilrah
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Re: Headtracker not working

Post by Kilrah »

They certainly had to do "something" to get both ports on there with no explicit software support, so it's possible they broke some features by doing so. We need someone to actually work out the schematic...
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jhsa
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Re: Headtracker not working

Post by jhsa »

They should provide the schematic.. we are asking on their forum. let's see if they publish it..
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Re: Headtracker not working

Post by FlyForest »

Hello,
I've run into the same issue. Could spmeone attach some schematic please :)
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Re: Headtracker not working

Post by FlyForest »

I've build working headtracker to use with 9xr. After some time the ppm input stop working.
Here is a demo:
[BBvideo 425,350]http://www.youtube.com/watch?v=Db_7zR83bs4[/BBvideo]

Now there is no respond to the signal. I have configured ppm1 and ppm2 in mixer menu; ppmsim off; trainer port on. checked everything twice and still no clue what went wrong.

My 9xr have atmega128a onboard. I've checked 4066 switch onboard and it seems to work. But I'm not sure how it should work because ppm-in at CPU (PE7) is connected to the input 3Y. If the PE7 is really ppm-in than it should be connector to one of the outputs of 4066 (as 3Z) right?

Maybe i'm complicating to much and the problem is in setup but I couldn't figure it out. Please help
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jhsa
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Re: Headtracker not working

Post by jhsa »

Maybe it is the tracker that stops sending a signal? Did you check if it happens with other radios?

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Kilrah
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Re: Headtracker not working

Post by Kilrah »

I would also first check the tracker hasn't simply failed.
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Re: Headtracker not working

Post by ReSt »

FlyForest wrote: But I'm not sure how it should work because ppm-in at CPU (PE7) is connected to the input 3Y. If the PE7 is really ppm-in than it should be connector to one of the outputs of 4066 (as 3Z) right?
If I understand that IC correctly, it is an analog switch; that is, if it is switched on, it provides a low resistive connection between 'Input' and 'Output', like a mechanical switch.
Therefore input and output have no real meaning, they are simply connected or interrupted.

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Re: Headtracker not working

Post by FlyForest »

Thank you very much for responses. I checked tracker's ppm out and it was ok all the time. It costs me a lots of nerves but eventually it started to work again. However I still don't know what the problem was. I reflashed radio with newest er9x without success and lastly wrote OpenTx firmware and it did the trick. I can just have hope that it won't happen again :)
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jhsa
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Re: Headtracker not working

Post by jhsa »

Very strange. The firmware shoild not matter.. I use er9x to teach other people and it never failed :o

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MikeB
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Re: Headtracker not working

Post by MikeB »

Changing the firmware shouldn't have any effect. I just checked the trainer input code and it is virtually identical in both cases.

You are, I assume, only sending 2 channels in? How long is the total frame time? I'm asking as there is code to detect the 'sync' pulse time, the frame time minus the two input pulses. Both er9x and openTx look for a pulse between 4mS and 16mS. If the sync pulse is over 16mS then it will not be detected.

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FlyForest
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Re: Headtracker not working

Post by FlyForest »

MikeB, I assumed that the ppm frame len is 22500, pause between channels is 300us. When I measure it on osciloscope it is very accurate. I'm sending 8 channels but of course only 2 are changing (default PPM1 and PPM2 but i can set any channels). I didn't know about sync pulse. My PPM looks like that:
Image
I also assumed the center len as 1210 which is recognised as 1500us in the radio. I didn't know why is it like that but since my solution worked I assumed it just have to be that way.
Please explain where that sync pulse should be? If before each frame then in my example I put 300us there (as you can see in the picture) - I must change it between 4-16ms right? Anyway lack of sync pulse could be the reason for unstable ppm input :)
Last edited by FlyForest on Sun Aug 24, 2014 5:22 pm, edited 3 times in total.
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jhsa
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Re: Headtracker not working

Post by jhsa »

Are you sure those values are correct? The values should be uS (micro seconds) and not ms (milliseconds).. 22500ms is the same as 22 and a half seconds :D A bit too long :mrgreen:

Anyway assuming the values are in microseconds, 660uS look a bit too low to me.. Center at 1210uS doesn't look like anything I know.. Which system uses these values? Or am I missing something?
Something doesn't really look right :)

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Re: Headtracker not working

Post by FlyForest »

oh, yes of course it is in us :D (22,5ms etc.) Anyway, as you can see in video, it works :) I did it by my expertise. I would like to know why the signals are as they are but I don't have enought knowledge about 9XR. Mayby is it like that because of to short sync pulse.

edit: I've changed previous picture so nobody would get confused.
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MikeB
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Re: Headtracker not working

Post by MikeB »

Your PPM signal looks fine. Each channel pulse time includes the 300uS pulse, so your channels are 1210+300 = 1510 uS.
The sync pulse is the long pulse between each set of 8 channel pulses. In the above, your channels are:
1610, 2060, 1510, 1510, 1510, 1510, 1510, 1510, a total time of 11.22 mS. Your sync pulse is therefore 22.5-11.22 = 11.28mS. It will change as you change each channel.

er9x does include some code that monitors the trainer input signal. If it goes away for a second, then use of the trainer input is stopped where possible.

One other possibility that will disable the trainer input is if you select PPM16 as your transmit protocol. THis sends 8 channels to the Tx module and 8 channels to the trainer port as an output, giving you 16 channels output altogether.

You can monitor the first 4 trainer input channels on the TRAINER menu. They show up at the bottom of the screen.

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Re: Headtracker not working

Post by FlyForest »

Thank you very much. I'll check it all again on er9x and OpenTx.
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jhsa
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Re: Headtracker not working

Post by jhsa »

Sorry about my PPM reading above. Mike is right. I think I got confused with all those numers there..

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Re: Headtracker not working

Post by FlyForest »

So I checked and everything is working :) Still I don't know why it wan't working, but It may be some my mistake or the hardware blocked cpu pin and needed reflashing or whatever...
I've corrected the ppm lengths to 1220 for center and +/-512us for turns. That additions 20us may be because of some cpu problem like 8Mhz is not enough to generate ideal 1200us by the cpu interrupts. Anyway the project works better than expected so maybe I'll make some documentation in free time.
Best regards

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