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ModdQuad / ModdOSD

Open source hardware/firmware project to replace the MAX7456 OSD chip commonly used in flight controllers.
GNU General Public License v3.0
11 stars 2 forks source link

[Question] VRx sync insertion #1

Open JyeSmith opened 4 years ago

JyeSmith commented 4 years ago

Firstly, very nice work!

The community is missing an opensource VRx with sync insertion. Do you see this project being able to be modified and used for something like this?

ModdQuad commented 4 years ago

While testing various MCUs I looked into creating a BlueBlocker / BSOD Blocker type product so I could fly on my bigscreen tv.

What I wanted to do was inject my own sync pulse if the pulse did not make it to the video RX because of transmission error. (This is similar to the black burst signal I use to generate video with no camera input synchronized to video).

To answer your question, While you could do something like this using an STM32G071, I would instead recommend using a STM32G4xx instead. It is a clock domain problem, If you had the same clock as the camera has, it would be trivial. Without that clock you need to be very careful to integrate the error between the two clock sources in your calculation. Its more of a signal processing problem then brute force. The G4 chip timers run at 170MHz and it has a better comparator which is more suited for this application.

On Tue, Dec 10, 2019 at 2:58 PM Jye notifications@github.com wrote:

Firstly, very nice work!

The community is missing an opensource VRx with sync insertion. Do you see this project being able to be modified and used for something like this?

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JyeSmith commented 4 years ago

Did you get very far with it?

Looking at the size of your OSD, if a board that size could be made for the BlueBlocker it would be an awesome add on to any 'dumb' VRx out there.

ModdQuad commented 4 years ago

If you want to try using a moddim board you would need to use the servo outputs. They are all hooked up to TIMER1 which can be cleared by the comparitor. Then you need a circuit that forces 0.1V during sync and keeps it > 0.385V during the signal to be NTSC compliant (minus the color burst). I would guess you could use a mosfet and a few zener diodes hooked to an open drain timer output plus a couple of op amps to buffer the whole thing, but I am a signal processing guy more than a hardware guy.

JyeSmith commented 4 years ago

but I am a signal processing guy more than a hardware guy.

Unfortunately I am neither 😅

If you ever come back to it Id be happy to hack along and I know someone elese who would be keen (a much better hardware guy).

Cheers

ModdQuad commented 4 years ago

It would be an interesting project, but the OSD project is something I am trying to squeeze in between jobs. Most of the software work left is unit testing of the register set, editing fonts and other boring tasks. Also to get any traction, I will need to design and build a FC, then sell it from my website before anyone will consider using the tech. Its just the way the world works, when it concerns money assume very conservative principles apply. I would gladly build such a contraption if crowdfunded but I do not have the time to figure that out, too many hats already.

AlessandroAU commented 4 years ago

If you ever change your mind, it's something Jye and I would love to add to our VRx project to do proper osd overlay. We are using an ESP32 as the main MCU. https://github.com/JyeSmith/FENIX-rx5808-pro-diversity/tree/esp32

ModdQuad commented 4 years ago

I do want to fly on a big screen tv. But I am not sure if it would actually work, temperature, vibration, etc will all effect the camera clock. I have a Voodoo Labs TBC10 that I could use as a substitute for the hardware part and run a software only test. But it is not something I can do with my 0603 sized board because I did not read the datasheet and used a mems oscillator. The upcoming mini 0201 sized board fixes the issue. May need change the oscillator frequency to a color burst multiple.

ksyz commented 2 years ago

Pity, that this went silent. Software OSD, an maybe even signal mixing would put open/community vrx on a different level. Not to mention replacement for 80s teletext style OSD everybody still sells/uses.

I think, if you ever decide to revive this project, community is now stronger then ever, with all expresslrs, edgetx, bf and other projects on the table.

ModdQuad commented 2 years ago

I wish I could open source the code, but the issue is more legal than anything else. I would need a not-for-profit LLC to protect myself. The courts do not understand technology and are biased to those with money or power. I decided that it was not worth the risk of being blamed for someone's poor piloting skills by some ambulance chaser. Then there is the general lack of interest for both the project videos and betaflight team integration (osd firmware updates, 4MHz clock out, synchronization). And my disinterest in sales and marketing.

On Tue, Nov 16, 2021 at 8:12 AM ksyz @.***> wrote:

Pity, that this went silent. Software OSD, an maybe even signal mixing would put open/community vrx on a different level. Not to mention replacement for 80s teletext style OSD everybody still sells/uses.

I think, if you ever decide to revive this project, community is now stronger then ever, with all expresslrs, edgetx, bf and other projects on the table.

— You are receiving this because you commented. Reply to this email directly, view it on GitHub https://github.com/ModdQuad/ModdOSD/issues/1#issuecomment-970428790, or unsubscribe https://github.com/notifications/unsubscribe-auth/AN74YTNHUHYBEFRSU7V4WY3UMJ7ITANCNFSM4JZGBGOQ . Triage notifications on the go with GitHub Mobile for iOS https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675 or Android https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub.

ksyz commented 2 years ago

I can hardly argue about possible legal challenges in the future, or any future. But for such cases there are organizations with a lot of experiences, as FSF and EFF. Drop am an email. Also, other two participants in this are core devs on ExpressLRS project. And control link or control software for a drone is probably more prone to legal issues, then OSD subsystem.

Now I'm a bit offtopic. But I would just love to see your project progress.

Thanks!