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Topic: Sainsmart 3.2" questions (Read 634 times) previous topic - next topic

steven6282

Nov 04, 2013, 05:11 pm Last Edit: Nov 04, 2013, 05:18 pm by steven6282 Reason: 1
Hoping someone here might be able to help me with some questions I have on this display.  It's a pretty cheap display that has touch built in.  I haven't been able to mess around with my arduino hobby in a while, and last time I did all the displays available were expensive, and it was hard to find one that would work at a descent speed with an arduino.

So my questions concerning this display is, first would an arduino be able to handle the processing and displaying of graphics very well?  And if so, how fast is it at doing full screen changes (like say I had a full screen image and wanted to change to a different full screen image).  The screen that I have now and played with before was a smaller one from SeedStudio and it sucked bad for things like this.  It would take an arduino mega 20 to 40 seconds to redraw an entire screen because it had to update every single pixel and was very slow.  This screen says it has a controller built in, so I don't know if that would help with problems like this?

Second, another problem I had with the screen I was using before is that you could not turn the backlight off for a lower power mode (you had to cut power to the screen completely which added to slowness since you had to redraw whatever was on it when turning it back on).  Does anyone know if you can do that with this screen?  I consider it essential for any projects that are going to have a touch interface but not need to always be on.

Lastly, what kind of feedback does it send regarding touches?  Is it pressure sensitive at all?  How fast is the touch update (if I were writing controls to display on the screen for dragging this would be a big deal).

Alternatively, does anyone have any recommendations for a better 3" to 4" screen without getting to pricey.  I have multiple projects I'd like to have touch screens on, so don't want to have to spend 100 dollars per screen lol.  Although I do have one or two projects that could do with a bigger screen like a 5" or 7" and would of course be willing to spend a little more on those.  So on that same note, if anyone has any recommendations for a screen in that size range that could be driven with an arduino I'd like to hear those as well.

Thanks for any information anyone has.

arduinodlb

I have one of the Sainsmart 3.2" screens. I got mine with a shield and a Mega. The shield only works on the Mega.

I haven't actually timed anything, but to draw an entire screen is definitely not 20 seconds. It's more in the order of less than a second I would guess, but I never do it so I'm not sure. I do put up a keypad which takes up the whole screen, and I really can't see the drawing as it comes up. It's "virtually" instantaneous. That is, I can see it is not instant, but I really can't make out the drawing. It's very quick.

No, the touchscreen doesn't seem to be pressure-sensitive. You just get x,y position. In terms of speed, my project has a slider on the screen that you move with your finger, and it works fine. The demo also has a drawing program. You can't move at lightning speed, but it's not a snails pace either.
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steven6282

Awesome thanks for the info!

I also used my head a little and searched for some youtube videos for the screen and found some to show me the speeds and they are quite adequate for my projects :)  A exponential amount better than the SeedStudio shield that I have.

So I just ordered two of these screens from Amazon :)

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