Question on which IC for touch screen

nicolad76

Hi everyone...I have e 4 wire 6,5 inches resist. touch screen and I am looking for a simple wayto use it with the prop. I am looking for a IC controller for such kind of device but I cannot get anywhere.
What I need is just the driver for the touch pad. The display itself is working fine.
Any suggestion?

Thanks
Nicola

Timothy D. Swieter

Nicola -

Are you requesting an IC to read the touchscreen part or to control the display? I am slightly confused.

If the touch screen is a resistive touchscreen then you may be able to use an ADC or maybe even read the resistance directly with the Propeller using and the counter as an ADC. I don't think that there is an specific IC for this need.

If you are asking for an IC to control the display, then we will need more information about the display. You might not need an IC here either though because the Propeller may be able to handle it.

Tell us more about what you are trying to do. I believe I saw some other threads at one time about touchscreen interfacing for resistive touchscreens. Do a search.parallax.com to find those threads.

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Timothy D. Swieter, E.I.
www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, uOLED-IOC, eProto for SunSPOT, BitScope
www.tdswieter.com

Rayman

I think there's a code in OBEX for reading a 4-wire resistive touch panel with just the Prop and a couple resistors...

SRLM

Nope, no object in the OBEX (at least that I could find)

Anyway, a 4-wire resistive touch screen only uses three wires at any one time, and you do not read the resistance. Rather, you apply the voltage across one direction, then read the voltage on the other axis (it acts as a voltage divider). This tells you the relative position. I have one, but unfortunately have not had a chance to play with it yet. I searched google, and it took me about ten pages of results to get three PDFs of any quality.

I don't have the links, but here are the document titles:

Using Serial Resistors to Reduce the Power Consumption of Resistive Touch Panels
Using resistive touch screens for human/machine interface
Compare All Resistive Touch Technologies


I got my screen from Mouser, made by Fujitsu. If you don't have a data sheet, take a look at theirs.

Paul Baker

ADS7846N
TSC2000IPW
TSC2003IPW
And there are quite a few variations of the above chips, goto http://www.digikey.com, type touch screen in thier search box then click on catagory: Analog to Digital Converters - Special Purpose

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Rayman

I found the thread where Ken·Peterson posted his 4-wire touchscreen code with circuit diagram:

http://forums.parallax.com/showthread.php?p=669411

I swear I remember seeing it OBEX, but maybe it's gone now...

Ken Peterson

I don't believe I ever got it onto the OBEX. I'll see if I can if there's sufficient interest, but right now I don't feel it's polished enough.

Nicolad: feel free to PM me if you have issues getting it to work.

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·"I have always wished that my computer would be as easy to use as my telephone.· My wish has come true.· I no longer know how to use my telephone."

- Bjarne Stroustrup

nicolad76

hey..u gave me a lot of nfo...thanks a lot......
sorry if i didn't reply on time but it happened tha i became father so my propeller has to wait [noparse]:)[/noparse]

thanks again!!!
Nicola

Rayman

Congrats! I suppose there are a few things more important than the Propeller... [noparse]:)[/noparse]

Ken Peterson

Nicola, contratulations!· I became a father last year and I've now found that many things will wait...and wait....and wait.· ·· But it's worth it!·

I'm using a 3.5" touch screen with the Propeller in my car.· It's been working great for months now.· It controls a navigation system.

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·"I have always wished that my computer would be as easy to use as my telephone.· My wish has come true.· I no longer know how to use my telephone."

- Bjarne Stroustrup