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[SOLVED] AR1100 Touchscreen Backpack Shorted Pins
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[SOLVED] AR1100 Touchscreen Backpack Shorted Pins

by Snail_ on Wed Feb 15, 2017 6:44 pm

Hello,

I've got an 800x480 AR1100 touchscreen backpack but the screen seems to be miscalibrated, as even though EDID shows an 800x480 screen, touching the screen moves the mouse cursor to the wrong place.

I am concerned that two pins on the AR1100 look like they're shorted (the PIXS and GND pins), and there's what looks like a solder bridge between them. Testing with a multimeter confirms this. Is this supposed to be the case?

This is the backpack:
https://learn.adafruit.com/adafruit-5-800x480-tft-hdmi-monitor-touchscreen-backpack/overview

and the AR1100 datasheet:
http://www.ti.com/lit/ds/symlink/tfp401.pdf

Thanks and best wishes
Last edited by Snail_ on Fri Feb 17, 2017 7:42 pm, edited 1 time in total.

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Re: AR1100 Touchscreen Backpack Shorted Pins

by adafruit2 on Thu Feb 16, 2017 2:52 pm

can you post a pic showing what pins are used? there's no PIXS pin in the schematic?

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Re: AR1100 Touchscreen Backpack Shorted Pins

by Snail_ on Fri Feb 17, 2017 2:08 pm

Sorry, was referring to the TFP401 chip.

This is the board (hard to see but the pins are bridged):
adafruit.jpg
adafruit.jpg (247.69 KiB) Viewed 645 times


The marked pins on the datasheet:
tfp401.png
tfp401.png (88.25 KiB) Viewed 645 times


and the datasheet for the chip in question (linked to in original post):
http://www.ti.com/lit/ds/symlink/tfp401.pdf

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Re: AR1100 Touchscreen Backpack Shorted Pins

by adafruit2 on Fri Feb 17, 2017 2:20 pm


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Re: AR1100 Touchscreen Backpack Shorted Pins

by Snail_ on Fri Feb 17, 2017 7:41 pm

Ahh, thanks I didn't know the schematic was public!

I fixed the screen issue by reflashing the Beaglebone, turns out it was unrelated. Thanks it looks like everything is working now.

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