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Author Topic: resistive touchscreen and arduino  (Read 3202 times)
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Hello all.
I am new on this forum (and in electronics in general), so thanx for your patience.

I have a 4-wire resistive touchscreen and I would like to know if it would be possible to plug it on the arduino (and later get xy values via maxmsp) ?
And if yes, a quickly explanation on how to plug those 4 wires would be great.
I've googled for hours, and I couldn't find anything, except that those wires indicate Yup, Xright, Ydown and Xleft.
As the touch screen is resistive only, would I need other external hardware or does the Arduino (and a home-made shell) is enough ?

Thanx again, and my apologies if this is a very stupid question.
_j.
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It would help if you could tell us something more about the touchscreen. Make, model number and so on...  :smiley

The four wire connection might use PS/2 mouse emulation or it might be serial, but that's hard to tell. I doubt if it is simply analog, bit even that's possible too.


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Hi.
It's a 5"x4" 4-wire resistive touchscreen by Microtouch (now 3M).
Don't have the reference number here.
I tried at that time to ask to 3M technical specifications but they just told me that this product was not made anymore, that they also have a 30$ usb micro-controller for this, but they would not sell it under 100 or so pieces.
When I asked them to give me any customer companies contact to order this usb ctl from them, I never had any answer.
That's why I thought about Arduino smiley-wink
Thanx for your help!
_j
« Last Edit: October 02, 2007, 09:45:33 am by josiano » Logged

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I have seen those touchscreen somewhere. It is possible that those resistors connect together in the middel of the screen. The wires come from the midpoints of the screen edges. Let's say you connect left and bottom to ground and right and top to +5V and the resistors are 500 ohm. Touching the center will give a left-right and top bottom value of 500.


         +y
          |
          |
-x ----O---- +x
          |
          |
         -y

Something like that. A pure analog thing. You can read the values with the analog inputs
« Last Edit: October 02, 2007, 12:34:25 pm by bigengineer » Logged

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Quote
The wires come from the midpoints of the screen edges.

exactly.

Quote
Let's say you connect left and bottom to ground and right and top to +5V and the resistors are 500 ohm. Touching the center will give a left-right and top bottom value of 500.

I'm gonna test that soon then.
Many thanx for your help gentlemen smiley
I'll update the post when this is done...
Oh, and by the way, I found the references:
touchscreen Multitouch 10641 A.
Cheers.
_j.
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hi:

does your touchscreen have circuitry or is it just the glass panel?  If you only have the panel, I suggest trying to hook up the touchscreen to a controller and interfacing arduino with that.  Texas Instruments makes a few touchscreen controllers and so doe Analog Devices.  And you can order a sample from both for free.

Texas Instruments has the ADS7843 4wire touch screen controller that uses an SPI interface, as well as the TSC2006 which uses the TWI/I2C interface.

Analog Devices has the AD7843 and the AD7877.  Both use SPI interface, and I think the difference is that the 7877 is a 12 bit resolution and the 7843 is 10 bit.

I recommend using the TSC2006 from TI because it is TWI and you can use the TWI library in arduino to communicate with the chip.

Also, read up on this article:
http://www.circuitcellar.com/library/print/0100/dahlin-114/index.htm

It is a great resource on resistive touch screens, how they work, and how to make them work.

Interfacing directly with the panel with arduino is also possible, but it is not as accurate as using a chip.  Granted, using surface-mount chips is difficult, you will need to order a break-out board from sparkfun to solder it....

-nima
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Thanx a lot nima !
Btw this article is great !
I will post any result when I have more time to test all this.
Cheers smiley
_j
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Sorry to drudge up an old post but did you figure this out?
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