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MinimOSD strange behaviour

Hi all!

I’m having big problems with minimosd, and after hours and hours of internet searching and testing and trying all possibilities, I have had no progress.

To sum up, the problem is:

  • If I try minimosd with no input video, I can see the osd information on black background but the image bright is very low. I’ve tried setting “OSD intensity” to maximum value in config osd software with same results. I see the same using PC video in capture and using FPV transmitter and FPV goggles.

  • If I connect a camera output video (I’ve tried with Eachine 1000TVL FPV Camera and with Xiaomi Yi camera with AV output) using AV PC video capture I see a correct camera image with OSD but very very low light B&W image. If I use FPV transmitter and FPV goggles I see the image completely distorted (Unsync?)

I’ve tried NTSC and PAL. Tried arducam 2.0, 2.2 and 2.4.1.3 versions. Tried resetting minimosd, powering max7456 from microcontroller side, powering from 12V with same results.

If I connect the camera output directly to FPV transmitter or AV PC Video capture it works fine and I see the image with no flickering and in perfect color.

What could be the problem? Maybe defective minimosd module? I’m afraid I’ll buy a new one and will have the same problems.

I have a chinese clone of minimosd, because as I know, 3DR does not exist anymore. Are there any better quality alternatives to minimosd?

Thanks in advance!

Here you can see some captures of what I’m talking about:

Just OSD. No input from camera:

.
OSD + camera input (Seen on PC AV video capture):

.
Same (OSD + camera) but seen on FPV goggles (PAL or NTSC selected correctly):

Seems a bit like a hardware issue.
But I’d probably try putting the nightghost minimosd-extra on it and see if that makes any difference.
as per this:
https://discuss.ardupilot.org/t/minimosd-bug-or-feature/29319/3?u=xfacta

I’m using this Hobbyking one:


It wasnt the cheapest around, but it is working as planned.

Also, check all your ground wiring (0v), maybe post a drawing or diagram of what you’ve got.

Hi xfacta,

I’ve tried nightghost minimosd-extra with the same results. I agree with you that might be a hardware problem. I yet ordered a few days ago a new pcb from aliexpress. If the problem continues I will buy the hobbyking’s one that you have recommended me.

This is the wiring diagram. I’ve soldered both top and bottom pcb side jumpers so the power of both the atmega and the video area is supplied by pixhawk telemetry port 5V.

Thanks a lot for your help!

Its your goggles…

And I’d power the OSD from a separate +5 volt BEC. If you don’t the OSD may “garbage up” when you arm the motors, and it will definitely get nasty when you throttle up. BTDT.

If you really want to get a decent display, I highly recommend MWOSD firmware. There are forks for APM (Mavlink), Pixhawk(PX4), and numerous flight controllers. I use it on a 250 racer with an Omnibus F4, and 3 aircraft (one hex and 2 quads) with Pixhawks.

If you want to learn more about FPV stuff, go here: https://www.rcgroups.com/fpv-equipment-862/

To me looks like a “tuning” issue. similar to the issues we used to have with analog TV reception when the TV tuner was not tuned perfectly to the transmission frequency. Maybe the output signal of your OSD is somehow not “right” in an electrical sense, looks as if the linejump signal is not perfectly clear. I’d try replacing components one by one until the issue goes away - root causing by elimination as you are planning to - or you find somebody with an osciloscop that can pinpoint the specific signal problem.

I have been using a basic minimOSD board and the night ghost version of minimosd FW very successfully - no reason for me to change to another one - which FW you use is more a matter of personal preference I think - minimOSD definitively works.

Have you checked that the 5v supply to the OSD is actually around 5.0v, and not something lower like 4volts?

Hi all! Thanks for the answers!

I’ve tried minimosd also on my TV analog input and there it works camera+osd but unfortunately it has intermitent 1-2 seconds black screens every 5-10 seconds. Obviously I can not flight in these circumstances.

Summarizing:
FPV goggles: see B&W and like not tunned image.
PC video capturer: see B&W very dark
TV analog in: Full color but intermitent black screens.

My conclusion is my minimosd is broken and each tunner acts different with the damaged video signal. I’ve bought a new minimosd but not received yet.

CLabeck I have an oscilloscope, but I do not know what to investigate. Do you know how to check minimosd with an oscilloscope?

I’ve done the tests with a laboratory power supply, so it is nothing about the BECs.

if anybody have any clue for why the same signal is seen completely different depending on receptor, please tell me.

Thanks again!

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