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Topic: Super cheap touchscreen LCD (Read 3523 times) previous topic - next topic

Super cheap touchscreen LCD

Hey guys,

I just wanted to share a "project" i've been messing with lately.  A while back I noticed some cheap ($7) 240 x 160 lcds on eBay with touchscreens.  Obviously I had to buy a few of them.  Since then, they've just been sitting on my desk shelf downstairs. Just recently I got around to hooking one up and making a little proto board for it.

The thing about these LCDs is that they don't have a controller -- you have to drive them yourself with a higher powered processor (PIC32).  Luckily, Matt Bommicino from CafeLogic did all the dirty work and wrote up a sweet site (including firmware) about how to drive these screens.





The coolest part of this is that I left my PicKit2 programmer at home, so I had to run it all from a ChipKit Uno32 using the default bootloader.  As you can see in the third picture (top right corner), the code uses about 25% of the processor time.  This includes a stripped-down version of Microchip's graphics library (ie clock, buttons, text, etc).

Here's the kicker:  If you already have a PIC32 lying around, this thing costs you under 15 bucks to set up!  A graphic lcd with backlight and touchscreen for <$20?!  I'll gladly share my board layout (once I fix it up for v2) if people are interested.

Link to screens: http://www.ebay.ca/itm/3-Graphic-LCD-Di ... 2314wt_905

Link to CafeLogic: http://www.cafelogic.com/articles-2/dri ... h-a-pic32/

Re: Super cheap touchscreen LCD

Reply #1
Fantastic thanks for sharing.


Re: Super cheap touchscreen LCD

Reply #3
I've been messing with the compiler optimization, and does it eve39r make a difference!

Level - Flash % - Ram % - CPU %

0 - 44 - 50 - 23.47
1 - 44 - 39 - 07.83
2 - 44 - 39 - 07.56
3 - 44 - 46 - 06.51
s - 44 - 38 - 07.63

This is with a frame rate of 30fps and a screen draw rate of 75fps.  Not only is it $15, but with optimization (I think you get up to level 2 free?) it only uses up a meager 8% of your CPU time!

Re: Super cheap touchscreen LCD

Reply #4
Nice. I've actually got one of these screens. I'm just waiting on a breakout board for the 0.5MM ribbon cable.

This is where I'm getting the breakout, http://http://www.tplabs.info/catalog/ffcfpc-dip-20-pin-adapter/
Bought my screen from the same ebay seller.

It looks like your breakout board has the ~+20v boost converter on it. What IC are using?

 

Re: Super cheap touchscreen LCD

Reply #5
I used a TPS61041 from TI.  As to why:  a) free samples, b) after looking at a lot of circuits, they seemed to be the simplest for the price range.  The 20v line only needs a few mA so I wanted to use a controller that was more suited to small currents.