Faulty Cap Touchscreen on 2.8 TFT LCD Breakout Board

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harvtech
 
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Faulty Cap Touchscreen on 2.8 TFT LCD Breakout Board

Post by harvtech »

I have now purchased three of Part No. 2090. Two are working perfectly as expected with my hardware and firmware. However, the last unit received from my last purchase appears to have a faulty touch screen while connected to the same hardware running the same firmware. It appears to be intermittent to the touch in one corner of the screen while its interrupt pin appears to be active without touching the screen. The display itself appears to be ok but it is of no use to me without a working touchscreen.
I would like to request a replacement ASAP as I am building multiple devices that use this product.

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mikeysklar
 
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Re: Faulty Cap Touchscreen on 2.8 TFT LCD Breakout Board

Post by mikeysklar »

What was the date of purchase for the non-working touchscreen?

Can you post a photo of the setup?

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harvtech
 
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Re: Faulty Cap Touchscreen on 2.8 TFT LCD Breakout Board

Post by harvtech »

Thank you for your response. Purchase date was 5/28/23. The setup was simply a swap with a working unit in a working setup so a photo will not provide any clue as to what was happening with the new unit.
As I reported it appeared to be an intermittent problem. I am happy to report that after reconnecting an EYESPI cable to the unit today the intermittent touch screen behavior did not happen. All I can think of is that it might have been something to do with the way the cable was aligned in the connector on the breakout board because there was no problem when another unit was connected to the same cable. I also cannot be sure if the cable I used today was the same one used when I experienced the problem because I put that one back in a bag along with others I had purchased.
So it appears that there really is nothing wrong with the new unit and there is no need to replace it.

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harvtech
 
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Re: Faulty Cap Touchscreen on 2.8 TFT LCD Breakout Board

Post by harvtech »

My Setup.jpg
My Setup.jpg (58.48 KiB) Viewed 91 times
After returning from a trip I was able to look further into the problem I experienced. This particular unit exhibits intermittent touch screen errors. It randomly signals a screen touch when no touch was made. It must also generate random coordinate errors as indicated by one touched button eliciting the response expected from another nearby button or simply not responding at all. The random nature of this behavior made it very difficult to trace. However, the bottom line is that this behavior does not occur when this particular unit is replaced with others that I have purchased for my project.
I would like this unit to be replaced as it is of no use to be without a working touch screen.

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harvtech
 
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Re: Faulty Cap Touchscreen on 2.8 TFT LCD Breakout Board

Post by harvtech »

To illustrate this issue my application code uses the touch screen interrupt output as an external interrupt that toggles the state off bool touch_flag.

//ISR
ICACHE_RAM_ATTR void touchdetect()
{
touch_flag = !touch_flag;
digitalWrite(touchInd_pin, touch_flag);
}

The state of touch_flag is monitored at an ESP32 output defined as touchInd_pin.

Attached are DSO waveforms of random events captured at that output that should not have occurred because the screen had not been touched.
Attachments
bogus touch 3.png
bogus touch 3.png (14.66 KiB) Viewed 83 times
bogus touch 2.png
bogus touch 2.png (12.79 KiB) Viewed 83 times
bogus touch 1.png
bogus touch 1.png (11.89 KiB) Viewed 83 times

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mikeysklar
 
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Re: Faulty Cap Touchscreen on 2.8 TFT LCD Breakout Board

Post by mikeysklar »

Sure, we can replace this unit.

Please e-mail [email protected] to request a replacement. They will need your order# and a link to this forum thread as your authorization. Thank you for the extensive testing.

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harvtech
 
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Re: Faulty Cap Touchscreen on 2.8 TFT LCD Breakout Board

Post by harvtech »

Thank you for your response. I have made that request.

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