Author Topic: Small TFT display, 5x5cm, for moving graphics, over SPI  (Read 7228 times)

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Offline peter-hTopic starter

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Re: Small TFT display, 5x5cm, for moving graphics, over SPI
« Reply #25 on: January 31, 2022, 09:31:17 am »
That algorithm will fail for polygons which have a notch. A simple case is an arrowhead. This will work



but this will break



Obviously code for all this has been developed, including polygons with holes, etc.

Yes; RAM is power :) Such a pity these fast ARM uCs have just 128k etc. Even SPI-attached RAM would be great.
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Online Nominal Animal

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Re: Small TFT display, 5x5cm, for moving graphics, over SPI
« Reply #26 on: January 31, 2022, 09:57:53 am »
That algorithm will fail for polygons which have a notch.
No, you just need to handle pairs of intersections on each y; and correctly handle polygon vertices as an intersection.  That then also handles self-intersecting polygons naturally using even-odd rule.  For each y, you get an even number of intersections.  Sort them in increasing order, and each consecutive pair forms a span (a horizontal line segment) that you need to fill on that y.
« Last Edit: January 31, 2022, 10:08:43 am by Nominal Animal »
 

Offline peter-hTopic starter

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Re: Small TFT display, 5x5cm, for moving graphics, over SPI
« Reply #27 on: February 03, 2022, 07:23:20 am »
I've decided to buy that 500 quid library mentioned earlier
https://www.eevblog.com/forum/projects/small-tft-display-5x5cm-for-moving-graphics-over-spi/msg3976907/#msg3976907
It will save a huge amount of time. It is apparent that it is fairly easy, with the free code examples, to set a pixel, but not much more.

I've spent some time getting DMA to work on 32F417 SPI3 because that will be needed
https://www.eevblog.com/forum/microcontrollers/32f417-spi-running-at-one-third-the-speed-it-should/msg3940687/#msg3940687
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Offline ve7xen

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Re: Small TFT display, 5x5cm, for moving graphics, over SPI
« Reply #28 on: February 03, 2022, 08:03:07 am »
Rather than buying a library to drive a framebuffer LCD, have you considered a Nextion module that includes a display controller? You use a Windows app to design the UI pages and then just send basic commands over UART to update the UI elements. There are other companies doing this too, maybe some cheap ones, but mostly they seem to target the industrial market and are kind of expensive.

Nextion have modules like NX3224T024 2.4" 320x240 for about $25. If you're not planning to build in quantity it makes a lot of sense.
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Offline peter-hTopic starter

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Re: Small TFT display, 5x5cm, for moving graphics, over SPI
« Reply #29 on: February 03, 2022, 10:58:57 am »
That's probably good for hobby / low volume / non-industrial but it ties you to a device which, if it goes out of production, lands you with a massive job. Whereas all the time you are using these "dumb" LCDs, you should be able to find an alternative.

The real issue is likely to be TFT panel availability. Normally you are stuck with a given size, to fit your box.

BTW what happened to the low temp issue? In say aviation one sometimes had a heater on the back of it. Hence OLEDs but they have a crap life. Wide temp range products tended to use vacuum fluorescent displays, which have lots of reliability issues too.
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Online T3sl4co1l

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Re: Small TFT display, 5x5cm, for moving graphics, over SPI
« Reply #30 on: February 03, 2022, 07:09:34 pm »
OTOH, it saves you a lot of upfront work, integrating that display.  Good not just for industrial and low-quantity but also quick-turn / short-TTM projects.  Get it out there earning money, cost reduce it later.  Some projects it's worth spending that up front, others more like this; just another option for doing business. :)

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Offline Bud

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Re: Small TFT display, 5x5cm, for moving graphics, over SPI
« Reply #31 on: February 03, 2022, 09:17:13 pm »
Nextion have modules like NX3224T024 2.4" 320x240 for about $25. If you're not planning to build in quantity it makes a lot of sense.
Thanks for the tip! Makes it a lot easier for a variety of hobby projects.
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