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Old Jan 27, 2015, 04:32 PM
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Pixhawk and MinimOSD

I am thinking of getting the px4 pixhawk or perhaps the apm or HK pilot. I have found that the MinimOSD is a commonly used osd for these flight controllers but I have also come across the mini osd with mavlink that looks very similar to me. Are these the same osd? I have seen some videos on how you can customize and configure the minimosd with AHI and all to your own liking which is nice so it would be great if these were the same osd. Maybe strange question but I want to buy the px4 and osd from the same website and the suggested osd there is called mini osd mavlink.
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Old Jan 27, 2015, 05:12 PM
Siv
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They are all the same. Having said that, not all are created equal. I have bought them from several suppliers (3dR, HK, eBay, witespy) and none have been reliable for me. The 3dR original was twice the price of the others but lasted the longest. I'm not sure if it's my wiring but they work fine on the bench but have fried in flight. A couple simply didn't work out the box and given the funny places you have to order from, I didn't bother sending them back.
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Old Jan 28, 2015, 05:15 AM
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Thanks! I think I have read something about an older version of them that had some issue with running on both 12v from the camera side and 5v from the apm side which made it run warm. Maybe this is corrected in later versions. If not, do you know if there is any suitable osd out there that lasts longer and is compatible with these flight controllers?
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Old Jan 28, 2015, 11:33 AM
Siv
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This is my experience only but the hassles with the OSD was the sole reason I switched from APM/PixHawk to the Eagle Tree Vector.

I have had great success with both the APM and PixHawk as a flight controller and when it was working the OSD was fine. It may be something to do with my power-up sequence but after a while the OSD stopped working reliably - I had to reset it after power up to make it appear correctly. Then a little while later it just turned to gibberish and the replacements either worked a couple of times and then failed or didn't work at all.

To my knowledge, there was no hardware development on the Mavlink OSD that fixed any problems with the dual voltage issue. But then it's been about a year since I last used one. I was very careful to ensure correct separation. It may be that you should use a separate 12V BEC to provide power to the OSD and VTx. But I gave up on that.
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Old Jan 28, 2015, 01:02 PM
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Yes, they are the same basic board, with slight differences. There are differences between v1.0 and v1.1, and also the placement of header pins. I've tried several different brands, costing anywhere from $15 to 40 with little correlation with price/longevity. They all seem to die eventually, although thankfully none of them have crapped out during a flight. I recommend buying two, so you have a backup. Also pay very close attention to the "Video In/Out" pin assignments. It's easy to reverse a connection, and I've fried one doing just this.

IMHO, the MinimOSD is the worst thing about using Pixhawk/APM. It's a fantastic flight controller system, but the OSD is generations behind the competitors. All the data needed is communicated via Mavlink messages, so anyone should be able to build a very nice OSD. I'd be willing to pay up to about $100 for a nice display like the Vector, with options like 5v/12v camera, and configurable in-flight menus. Can someone please make a better one???
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Old Jan 30, 2015, 01:11 PM
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Ah, this is really great info. I wouldn't buy the apm or pixhawk if there is no reliable osd. I have read some now about different wirings that might help, but considering your reports it still feels rather risky investing in this system. By the way, I have a 4 pin ftdi from an earlier autopilot, you think it'll work with the miminosd as well?
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Old Jan 31, 2015, 10:03 PM
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Quote:
Originally Posted by TwoHeadsBrewing View Post

IMHO, the MinimOSD is the worst thing about using Pixhawk/APM. It's a fantastic flight controller system, but the OSD is generations behind the competitors. All the data needed is communicated via Mavlink messages, so anyone should be able to build a very nice OSD. I'd be willing to pay up to about $100 for a nice display like the Vector, with options like 5v/12v camera, and configurable in-flight menus. Can someone please make a better one???
Amen!
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Old Feb 01, 2015, 05:19 AM
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It seems there are minimosds out there now where the 12v switcher can be bypassed by soldering some jumpers so that the osd can be powered with just a 5v source. Maybe there could be other problems with the osd not pertaining to this issue but I have also heard of people that are very happy with their minimosd, just take a look at the reviews at hobbyking.
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Old Feb 01, 2015, 05:50 PM
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It's not that MinimOSD is that terrible, it just hasn't been that reliable for me. It also pales in comparison to the new EagleTree Vector display. It has all the necessary information, and can be wired up with just a little bit of soldering, so it's adequate. But with a plane/multirotor worth >$1000 I would like to have something I have the ultimate confidence in.

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Originally Posted by ChrisP92 View Post
It seems there are minimosds out there now where the 12v switcher can be bypassed by soldering some jumpers so that the osd can be powered with just a 5v source. Maybe there could be other problems with the osd not pertaining to this issue but I have also heard of people that are very happy with their minimosd, just take a look at the reviews at hobbyking.
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Old Feb 02, 2015, 02:13 PM
Siv
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Quote:
Originally Posted by ChrisP92 View Post
It seems there are minimosds out there now where the 12v switcher can be bypassed by soldering some jumpers so that the osd can be powered with just a 5v source. Maybe there could be other problems with the osd not pertaining to this issue but I have also heard of people that are very happy with their minimosd, just take a look at the reviews at hobbyking.
Most allow you to solder jumpers and have both sides of the board (5V digital and normally 12V analogue) powered by 5V but this can introduce lines into your video. It's also a sure fire way to fry your board if you accidentally add 12V to the whole board (ask me how I know this)!
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Old Feb 05, 2015, 04:26 PM
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Will there be lines even if the 5V supply is relatively clean, ie. is the noise created in the board itself?
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Old Feb 06, 2015, 10:58 AM
Siv
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I think it's from the board itself. The 5V side is digital and the 12V side is analogue and I believe when the power is shared there is opportunity for noise from the digital side coming to the analogue side.

I'm no expert on this, I read it on a thread either here or on fpvlabs. I've always run 12V on the analogue side so can't comment if there really is interference from personal experience.
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Old Feb 06, 2015, 11:36 AM
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Well, just to throw a wrench in the gears...

In my previous build, I ran the MinimOSD with both 5v from the Pixhawk, and 12v on the cam/Tx side. The 12v was supplied via a second dedicated video battery. No lines were present in my video.

In my current build, I'm only supplying the MinimOSD with 5v from the Pixhawk. The 12v bypasses the MinimOSD and only the Ground and Video wires are connected on the both the input/output pins. This is a shared battery setup (4s), with a step-down regulator providing 12v. Now I've got very fine horizontal lines in my video.

It's likely to do with sharing the same battery which is introducing pulses. I have ordered this L-C filter kit for $3.50. It's supposed to go on your video power supply wire to clean up the video.
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Old Feb 06, 2015, 11:55 AM
Siv
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My data point is that I run single battery (3S) with a BEC to the 5V side and have a Let's FPV filter on the 12V going to the OSD/VTx. No lines.
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Old Feb 06, 2015, 12:03 PM
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I just plugged in 14.8v flight battery to the power module, with a separate 12v battery for the video power. No lines.

I'm still going to solder up a filter, since my flight battery is actually 2x6600mah 4s. Plenty of power there and only one voltage to keep track of.
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