8 channel issue with FrSky V8R7-II

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Lioon
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8 channel issue with FrSky V8R7-II

Post by Lioon » Thu Aug 01, 2013 11:22 pm

Hi,

I have a Turnigy 9x with the newest er9x firmware on it. The transmitter is a FrSky DJT module. As receiver I have a FrSky V8R7-II. Normally I use 7 channels with this reveiver but today I tried it with all 8 channels set and I had massive problems after take off: My copter did not react to my roll and pitch inputs. The logs of my copter later showed that the flight controller (APM 2.5) never got any roll and pitch inputs from the receiver despite my stick movement.

Then I switched back to 7 channels (deleting the mixer for CH8 in er9x) and everything worked.

Has anybody an idea what was the problem? I do not use CPPM (the V8R7-II has none), so it cannot be the known FrSky CPPM issue.

All the best,
Markus

Update: It was an connection problem, no FrSky or er9x problem!
Last edited by Lioon on Tue Dec 23, 2014 12:00 am, edited 1 time in total.

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ShowMaster
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Re: 8 channel issue with FrSky V8R7-II

Post by ShowMaster » Fri Aug 02, 2013 1:39 am

Could it be your frame length setting in er9x?
It's the only variable I can think of that's involved with the numbers of channels.

mpjf01
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Re: 8 channel issue with FrSky V8R7-II

Post by mpjf01 » Fri Aug 02, 2013 4:16 am

Can you check that all channels work as they should with the Rx connected to just one servo, same Tx settings, one channel at a time? If they do then I would be looking for the problem in the APM setup. If ch8 does not work then the Rx may be faulty (assuming that your Tx is set up correctly).

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MikeB
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Re: 8 channel issue with FrSky V8R7-II

Post by MikeB » Fri Aug 02, 2013 8:29 am

Curious! You must have 8 channels (at least) selected as the number of channels is set in steps of 2 (4, 6, 8, 10 etc.). If you have no mixer set for channel 8, then it will send a "middle setting (1.5mS) pulse for that channel.
What, if anything, does your flight controller use channel 8 for?

Mike.
ersky9x/er9x developer
The difficult we do immediately,
The impossible takes a little longer!

Lioon
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Re: 8 channel issue with FrSky V8R7-II

Post by Lioon » Fri Aug 02, 2013 3:39 pm

ShowMaster wrote:Could it be your frame length setting in er9x?
What settings do you suggest? I use the default values (frame length: 22,5 mSec. ppm delay: 300 uSec. pulse shift polarity: positive).
mpjf01 wrote:Can you check that all channels work as they should with the Rx connected to just one servo, same Tx settings, one channel at a time?
I did not try that, because I do not have servos but 4 ESCs (for it's a quadrocopter). But I checked all channels during radio calibration, a procedure with the copter connected to a computer via USB: With 7 Channels (or better: mixers set for CH1 to CH7, no mixer set for CH8) there was no problem. With mixer set for CH8 one channel (CH4) sometimes showed a different level than stick input. During a test flight it were CH1 and CH2 which tilted (no reaction to my inputs).
MikeB wrote:Curious! You must have 8 channels (at least) selected...
What, if anything, does your flight controller use channel 8 for?
Yes, I have 8 channels selected. CH8 does nothing important, it's just a switch to save waypoints. But anyway, it was not CH8, which had an issue, but CH1 and CH2... Without a mixer set for CH8 everything goes fine...

Markus


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MikeB
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Re: 8 channel issue with FrSky V8R7-II

Post by MikeB » Fri Aug 02, 2013 6:11 pm

What I'm saying is that with channel8 in the centre (1.5mS) all worked fine, but when you set channel 8 to something else (what exactly is the mix you have?), it goes wrong.

Are the 'BARS' on the tx screen showing the outputs are working correctly?

Mike.
ersky9x/er9x developer
The difficult we do immediately,
The impossible takes a little longer!

Lioon
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Re: 8 channel issue with FrSky V8R7-II

Post by Lioon » Fri Aug 02, 2013 7:31 pm

MikeB wrote:What I'm saying is that with channel8 in the centre (1.5mS) all worked fine, but when you set channel 8 to something else (what exactly is the mix you have?), it goes wrong.
Yes, it seems that's the problem.

I attached a screenshot with my mixes.
MikeB wrote:Are the 'BARS' on the tx screen showing the outputs are working correctly?
Yes.
Attachments
Editing model 2 TBS Disco  02.08.2013 212636.jpg

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MikeB
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Re: 8 channel issue with FrSky V8R7-II

Post by MikeB » Fri Aug 02, 2013 7:43 pm

Instead of FULL try using 3POS as the source with no switch. This will give you -100. 0 and +100 as output on channel 8, so in the ID1 position you should have the same as no mix.

If in ID0 and/or ID2 you get problems, you could try reducing the weight to see if it then works.

Mike.
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The difficult we do immediately,
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Lioon
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Re: 8 channel issue with FrSky V8R7-II

Post by Lioon » Fri Aug 02, 2013 9:20 pm

Thanks, I'll try that. In the meantime, I need to find out if it is in deed no FrSky issue at all, but actually an APM issue. Because everything seems to work fine, if I connect servos to the receiver instead the APM. Strange....

Update: It was an connection problem, no FrSky or er9x problem!

juanquy
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Re: 8 channel issue with FrSky V8R7-II

Post by juanquy » Sun Oct 01, 2017 2:29 am

V8R7-II? That RX is only 7 channels , not sure if support sbus, ppm or cppm but Is it only 7 ch for sure.

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