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Forum Index : Microcontroller and PC projects : DUMB DISPLAY

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PeterB
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Joined: 05/02/2015
Location: Australia
Posts: 639
Posted: 09:16am 23 Oct 2019
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If this works it is a photo of my RPI ZERO driving a $50 7in truck rear view display.
The text is more readable than the photo indicates but is not perfect. It's like my writing, if you know what it says you can read it.
How do you photograph these things?
I still can't get mmbasic to work but the display does work and that is what I set out to prove/disprove.

Peter
 
PeterB
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Joined: 05/02/2015
Location: Australia
Posts: 639
Posted: 12:56am 03 Nov 2019
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Back again.
mmbasic is working and text does look better than pi text.
I can do basic graphics using OPTION LCDPANEL HDMI and my POLYGON looks good.
Advanced graphics gives DISPLAY NOT CONFIGURED. Has this been solved please.

Peter

edit. I should make it clear I am using video / TV / AV
Edited 2019-11-03 11:01 by PeterB
 
PeterB
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Joined: 05/02/2015
Location: Australia
Posts: 639
Posted: 11:21pm 09 Nov 2019
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G'Day All

This thread has been going for a long time and has been read by over 2000 people and that begs the question, has anybody got anything out of it?
I set out to discover if a cheap display could interface with mmbasic via a PIC.
I think I have the answer to my question and now I have a heap of RPI ZERO bits. What to do with them?
I hope some people got something out of it.

Peter
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 12:02am 10 Nov 2019
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All my adventures into the video world have been with just pure home brew hardware.

But how about pinching a plug in video card out of an old computer, and interfacing to the data and address lines of that ?  

Let the video card generate the actual high frequency video in whatever standard and resolution you require. Its a bit clunky, but it should be possible.
Cheers,  Tony.
 
PeterB
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Joined: 05/02/2015
Location: Australia
Posts: 639
Posted: 12:30am 10 Nov 2019
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G'Day Tony

The starting point for all this was, can a 7 in truck rear view display be used with a PIC? The answer is, Only if somebody designs a mmbasic to TV converter. I like to think I could have done it once, but not now.
However, the pi zero costs $10, can run mmbasic and has a TV output so my question has been answered in a round-about way.
The reason for using a truck display was they come in a reasonable plastic case and are cheap.
Your idea reminded me of when I was younger, Dick Smith sold a blank board that plugged into a PC and gave address, data & space for some hardware. I could design all sorts of things for that but I had to get the young blokes to write the code.

Peter
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 01:57am 10 Nov 2019
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I suppose it depends on what you really need in the way of performance.
If its just plain text or some very basic graphics, its probably not too difficult.

As soon as things get complicated it requires some pretty fast high frequency circuitry to get even barely acceptable results.

I cannot now remember what I bought it for, but at one stage I purchased a low cost composite video in, VGA out box. It worked in a fashion, but the pictures it produced were pretty awful.

All this stuff appears good in the advertisement, but usually there are zero specifications, and in the end you probably get a lot less than you pay for.
Cheers,  Tony.
 
BrianP
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Joined: 30/03/2017
Location: Australia
Posts: 292
Posted: 02:06am 10 Nov 2019
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  Warpspeed said  But how about pinching a plug in video card out of an old computer, and interfacing to the data and address lines of that ?  

Let the video card generate the actual high frequency video in whatever standard and resolution you require. Its a bit clunky, but it should be possible.

Would you not need a compatible driver to be able to talk to it?

B
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 03:09am 10 Nov 2019
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  BrianP said  
  Warpspeed said  But how about pinching a plug in video card out of an old computer, and interfacing to the data and address lines of that ?  

Let the video card generate the actual high frequency video in whatever standard and resolution you require. Its a bit clunky, but it should be possible.

Would you not need a compatible driver to be able to talk to it?

B

I would expect the video generator chip would have a lot of internal registers that would need initialising at boot, but then it should be fairly straightforward after that. Just direct writes to the video rams from the CPU.
Cheers,  Tony.
 
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