TFT LCD screen with touch screen not working
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TFT LCD screen with touch screen not working

by bit.cyber on Fri Dec 07, 2012 4:26 am

Hi,
This week I purchased a TFT LCD shield (from a listed French distributor), received it and got everything working. At least seemingly - now I'm having problems...

Basically the touch screen feature has stopped working. The display itself still works fine. I've been using the TFT paint program to try it out. What's weird is that it was working yesterday - although it was a little flaky at first - and today nothing.

So here's a summary of what I'm using:
    Arduino MEGA 2560
    2.8" TFT LCD shield v1.1
    Arduino software v1.0.2
    Latest TFT LCD software
I've also tested it on a second "clean" PC system just to make sure. Still nothing. The serial monitor also reports nothing.

Any thoughts or help from the community as to where I should start debugging the board?

Two maybe related / maybe not related points would be:
    1. I mention flaky initial operation above - at first the touch feature also didn't work, but after a couple of re-plugging the board in and getting all the software work the issue went away. I can't say whether there really was an issue here or not.
    2. When the touch functionality of the screen was working, it was badly "calibrated". By this I mean using the paint program to draw a line in the centre of the screen did as expected, but close to the edge of the screen, the line was significantly offset. Has anyone else seen this? This only was true for the X-axis, the Y-axis worked fine.
Thanks in advance, Colin
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Re: TFT LCD screen with touch screen not working

by bit.cyber on Fri Dec 07, 2012 6:40 am

It would seem the plot thickens...

I was doing some further testing (read: trying to get the thing to work) and noticed the following:
    I still have the protective sheet on the screen.
    I went to unpeel part of it and then re-stick it and happened to run my finger across the part of the screen where contacts for the touch sensor are located (In a horizontal position, this is either the right bottom or top left).
    Then the touch functionality worked again!

It would seem there's an intermittent contact here. Has anyone else noticed something similar?

Another side note: At all times I've been testing the board and screen in a proper ESD set-up. Everything is grounded including me, so it's not like something has been damaged from ESD. Besides my most recent experience would suggest this isn't the problem...

Should I be seeking a refund / replacement?
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Re: TFT LCD screen with touch screen not working

by adafruit_support_bill on Fri Dec 07, 2012 8:36 am

Hi Colin,
I went to unpeel part of it and then re-stick it and happened to run my finger across the part of the screen where contacts for the touch sensor are located (In a horizontal position, this is either the right bottom or top left).
Then the touch functionality worked again!

It sounds like the flex connector for the touch-screen is damaged and making intermittent contact. These are rather delicate, but it sounds like you are exercising reasonable care in handling. Contact support@adafruit.com with a link to this thread to arrange for a replacement.
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Re: TFT LCD screen with touch screen not working

by bit.cyber on Fri Dec 07, 2012 10:49 am

Hi adafruit_support - thanks for your posting.

I did a little further testing and found that if I carefully, but firmly press on the set of four contacts then the problem no longer persists. Upon removing the pressure, the touch screen capabilities may or may not work, though it's usually just a matter of a minute or so before again the it no longer works.

So it would definitely seem to be an issue with the connection. Beyond this I would say the screen is great (of course when working)! Exactly what I was looking for, being a small all-in-one display and user interface for a frequency reference project that I'm working on (details available here: http://aethersdr.org/blogs/colin/frequency_standard).

Thanks for your kind offer to arrange a replacement - I'll do as you suggest.
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