RVOSD v5.02 problem: autopilot twitching servos every 2 seconds.

[turdsurfer]

I'm having a problem with my new and unused RVOSD v5.02 so I hope it can be solved so that I can start to fly FPV...

Several seconds after powering up, any control movement to lower than neutral (150ms) positions causes all controls to briefly twitch about every 2 seconds while 'autopilot enabled' simultaneously flickers in the display.

I'm using RVOSD in combination with a Scherrer UHF long range RX connected via combined PPM channel.
It doesn't make a difference whether I connect the RSSI cable or not.
It doesn't make a difference whether I use a lower or higher than normal throttle failsafe.
This bug isn't listed in the firmware changes up to 5.05.

This is a video that displays the problem. Watch as I hold full right aileron (< 150ms) constantly until the problem starts occuring:


Thanks,
Craig

[Alex Villa]

First, try to keep the transmitter away from the plane, increase distance to 3-4 mts. Sometimes is just the 433Mhz RF field around the transmitter affecting capture modules of the microcontroller.
Also some transmitters seem to have a different repetition period on the PPM combined frame. This is the cause of that problem. You will have to use separated inputs to RVOSD until I can fix this. If someone send me an oscilloscope capture of this period repetition I could fix it immediately.

[turdsurfer]

Thanks for the quick response. I just did a test and walked tens of meters away without the TX antenna and still had the same problem. I've asked Thomas Scherrer if he could help by giving you the oscilloscope capture (since he uses the same transmitter and of course TX module) in this thread:
http://www.rcgroups.com/forums/showt...6#post19838592

[Gary Evans]

You need to disconnect one thing at a time to determine exactly what is causing the problem. If may not be the Tx.

[turdsurfer]

I just tested the RVOSD with separate inputs instead of combined PPM and I can confirm that it now works this way.
On a side node: if I don't connect the aux input cable when using separate inputs, then the autopilot periodically flickers on and off causing the servo's to sound like short salvoes from a slow machine-gun with about 1 second pauses in between. It's not the same as the original problem, but it does follow a repeating pattern too.

@Gary: Unfortunately I read your message after I changed the PPM connections. Anyway, the video TX was already disconnected in these tests as I fed the output directly into my FPV-Japan DVR. It also occurred previously with the video TX on, so that excludes the video TX as the source. I can't exclude the camera as the source yet, but since it's a quiet 5v camera and since the PPM input change has made the twitching go away, I doubt very much that it is camera related. In any case, I'll rerun both PPM input tests again without camera connected if Alex thinks that may help.

[turdsurfer]

Alex, does this answer help at all?
http://www.rcgroups.com/forums/showp...postcount=9238
Are you perhaps able to get your hands on a Multiplex Royal Pro / Royal Evo RC system as I don't have an oscilloscope?

[turdsurfer]

I did some more testing by feeding the PPM stream from my Multiplex Royal Pro 7 transmitter straight into the RVOSD using combined PPM (bypassing the Scherrer UHF module) and the same problem occurred. So that excludes Scherrer UHF from the problem. If only I had an oscilloscope or some kind of mini PPM recording device to record the stream for Alex.

[turdsurfer]

Hi Alex,
Here is a list of the Multiplex Evo repeat times if that's what you need:
http://www.rcgroups.com/forums/showp...postcount=9248
Thanks,
Craig

[turdsurfer]

Ping

[Alex Villa]

I will make some mods on the next patch so hopefully the combined PPM will work with this.