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Forum Index : Microcontroller and PC projects : Composite video with colour Maximite
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| Greg Fordyce Senior Member  Joined: 16/09/2011 Location: United KingdomPosts: 153 |
Wow! A colour maximite, well done Geoff. 
I noticed that the composite video output has been dropped. Shame because this was very useful for some projects, small 4 inch lcd dispays from ebay are dirt cheap for providing a user interface. I would like to figure out a way to connect the VGA output to a composite video screen. Pal with the 240x216 mode would be perfect. I've seen adapters on ebay, don't know if they would work. Anyone have ideas on how to implement this. Or a source of small cheap vga monitors in the 4 to 7 inch range. Greg |
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djuqa Guru  Joined: 23/11/2011 Location: AustraliaPosts: 447 |
The colour maximite still has composite output option. It is available on the VGA connector. The documentation shows the connection details. VK4MU MicroController Units |
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MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
The composite will however be black and white. Making colour composite is very difficult without using special IC's. I would love to find a way to get some fixed colour on a composite signal. White text on Blue background would be very nice. I currently use a homemade maximite on a navigation screen that has a rearview camera connection. That works great. The black and white though gives the impression of going back to the 50's. :) Microblocks. Build with logic. |
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| Greg Fordyce Senior Member Joined: 16/09/2011 Location: United KingdomPosts: 153 |
It does indeed look like you need a encoder IC to get colour composite from the VGA. One possible chip is Analog Devices AD725 although there are other chips out there as well. I've gone the lazy route and ordered one of these. VGA to video adapter Now all I need is a colour maximite!  |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5036 |
Yes its very difficult to create colour composite video, compared to mono-composite and VGA colour. I'm with Greg and will use mono-composite, and am glad its available in the latest MMBasic. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
Greg, If you got it to work i would be very interested. Normally you would need to change the source to generate the right timings. The way the cheaper vga to video adapters (also homemade with ad725) work is to adjust the resolution and timings with software on a vga video card. In our case we would need to use the composite timings from the maximite and the vga colour information at the same time. I think this will not be too complicated as the timings the mm uses for composite video have been shown to work very well. The expensive ones have a frame buffer and generate the timings in a separate circuit. If the device you linked to is doing it with a frame buffer and still be cheap that would be the solution i have been looking for. I am curious what will be inside the box. Microblocks. Build with logic. |
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| Greg Fordyce Senior Member Joined: 16/09/2011 Location: United KingdomPosts: 153 |
I'll crack it open when it arrives and post pics. I am waiting now for someone to do a fully built CMM, I don't have time to build one from a kit at the moment. So once I get my hands on both items I will post results. Greg |
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| Frank N. Furter Guru Joined: 28/05/2012 Location: GermanyPosts: 815 |
Hello Greg, I have the same adapter and it works very well with my monitor and my UBW32-Colour-Maximite. I bought it at Amazon Marketplace in Germany. The picture is a little bit unsharp and does a little bit flicker but it is ok! The adapter have a very useful on screen menue for height, width, contrast, saturation, sharpness, flickering... It's a very nice Gadget Frank |
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| Greg Fordyce Senior Member Joined: 16/09/2011 Location: United KingdomPosts: 153 |
Thanks Frank, nice to know I am on the right track.  |
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| Greg Fordyce Senior Member Joined: 16/09/2011 Location: United KingdomPosts: 153 |
Got the VGA-Video adapter today, very quick delivery! Here's what I got. 
As promised I've opened it up, with the back cover off you see this. The big chip is some SDRAM. 
There must be a video encoder chip on the other side, and sure enough; 
So how's it work? Well I only have an original MM, but here is MAXMAN on a small 7 inch lcd screen. 
So it seems to do all I want it to do, and Frank has already said it works with his CMM. I plan on using either large fonts or mode 4 for a user interface so the small size of the standard fonts won't be an issue. I suppose if the MM genie granted me one wish, it would be to have the option of larger fonts while using the full screen editor for quick changes to code without having to connect a vga monitor or laptop to get a readable editor screen.
Overall I am quite pleased with the results and quite impressed with what I got for 12.50GBP. EDIT: the SDRAM is a EtronTech EM636165 and the encoder chip is a VX1937, datasheets availible on google. |
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| MicroBlocks Guru Joined: 12/05/2012 Location: ThailandPosts: 2209 |
Thanks very much for the pictures and test! It is great! The 'expensive' ones that use the frame technology are finally cheap. :) I ordered two with VGA to Video converter on ebay. Only US$12.56 a piece and free shipping. Microblocks. Build with logic. |
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