[TriEmbed] Pi Zero W -- Touch Display Troubleshooting

[Huan Truong]

You could try watching the dmesg for any disconnection of usb

$ sudo dmesg -w

Then touch the screen and see if there's anything weird. 

You could also watch for x events. 

$ xev




Huan Truong
tnhh.net

On Jun 6, 2022, at 5:38 PM, Ron Craig via TriEmbed <triembed at triembed.org> wrote:


Hi, gang.

I bought this display from Amazon. It states it works with the Pi Zero, but I cannot get Touch to work on that. Touch works fine on a Pi 4B, but not the Zero.
Any hints?

I have made my own cables where needed, but Touchscreen still does not work.  I am including my wiring setup below.  Am I missing something?  The arrow on the OS screen moves the first time I touch the screen, but will not move after that.  I think it is a software issue?  Are there drivers needed for the Zero?
pi at hamclock:~ $ cat /etc/os-release
PRETTY_NAME="Raspbian GNU/Linux 10 (buster)"
NAME="Raspbian GNU/Linux"
VERSION_ID="10"
VERSION="10 (buster)"
VERSION_CODENAME=buster
ID=raspbian
ID_LIKE=debian
HOME_URL="http://www.raspbian.org/"
SUPPORT_URL="http://www.raspbian.org/RaspbianForums"
BUG_REPORT_URL="http://www.raspbian.org/RaspbianBugs"
pi at hamclock:~ $ uname -a
Linux hamclock 5.10.103+ #1529 Tue Mar 8 12:19:18 GMT 2022 armv6l GNU/Linux

In the picture:
1: Power Block (5V 3.5A) to MICRO USB power connector on the Zero W.  No under voltage warnings. All looks good.
2: DIY 4-wire cable from JST to MICRO USB connector on the Zero W. Substitute for the 5V+Touch connector on the side.
3: Supplied FPC to MINI HDMI connector on the Zero.  Reaches fine once I moved the Zero to another location (was too short if the Zero was installed where suggested).


I've put Kapton tape on the back of the Zero W to prevent any electrical shorts with the unused mounting post.

On bootup to 32-bit Raspberry OS, the desktop appears properly and the picture looks great.  I can touch the screen EXACTLY ONE TIME, and the arrow cursor will move to where I touched the screen.  It never moves after that.

The application I use does not require a keyboard if I can use a touchscreen. Without touch, I need a bluetooth mouse, which I would rather not use. There are less expensive non-touch screens I think I could use if touch will not work. 

Any help is greatly appreciated. I've already printed a nice case and swinging mounting arm for this display, so I would love to keep it and use it if I can get touch to work.

Note that I've also tried power through the 5V IN connector, but the behavior is exactly the same.

Generally, are there any gotchas with Touch and the Zero or Raspberry OS in general I could try?

Best,
-- 
Ron Craig   KO4RON
J'ai bonne espérance!
       
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