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7" Touch Display; resistive touch not working
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Please be positive and constructive with your questions and comments.

7" Touch Display; resistive touch not working

by mmoralls on Tue Dec 24, 2019 5:24 pm

Hello,

I hope someone can help me. My project is an internet radio and I'm having trouble getting the touch part of the screen working. There were no instructions (driver to add or configuration) and I just plugged it in thinking it would just work. I have the Pi3+, the latest NOOBs (3.2.1) version installed and the display part is working fine. The power to the screen was an issue when I plugged it into the Pi and the screen was blank. I then plugged it into my desktop PC that had a 3.0 port and now it works fine (from a previous post and a power issue). So I plan on buying an adapter so I can go back to having the power come from the Pi.

I have looked through some of the previous posts to find a situation such as mine but can't seem to determine what is wrong or what I'm missing. I have done an update.

2396 - 7" Touch Display 1024x600 - Mini Driver

Here is output of lsusb:

pi@raspberrypi:~ $ sudo lsusb
Bus 001 Device 004: ID 248a:00da Maxxter
Bus 001 Device 005: ID 0424:7800 Standard Microsystems Corp.
Bus 001 Device 003: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
Bus 001 Device 002: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Much obliged!

mmoralls
 
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Re: 7" Touch Display; resistive touch not working

by alphanumeric on Wed Dec 25, 2019 1:15 pm

Which screen exactly? The touch signal / data likely comes through the USB cable / connection. It will if it used HDMI as its input.

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Re: 7" Touch Display; resistive touch not working

by mmoralls on Wed Dec 25, 2019 3:44 pm

Ok, the data cable drives the touch part. The one I'm using came with the driver board and maybe I need to find a better one. I'll give that a try.

Thanks!

mmoralls
 
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Re: 7" Touch Display; resistive touch not working

by alphanumeric on Wed Dec 25, 2019 4:18 pm

I had this one, https://learn.adafruit.com/adafruit-5-800x480-tft-hdmi-monitor-touchscreen-backpack
The two cables plugging in and sticking out the side was the only thing that bugged me. It just didn't work with my mounting setup.
The touch was via the USB cable, that also powered it.
I replaced it with the Pi Foundation 7 inch touch screen. It has a nice black bezel around it and the cables are all out of site on the back. It uses the Pi's DSI cable for display and touch data. The touch is capacitive though not resistive. Pluses and minuses with that though. It has a nice hard gorilla glass cover, but your normal average stylus isn't going to work with it.
The resistive touch uses pressure to trigger it so anything that presses the screen will work. You just don't want to press to hard and damage the screen, its on the soft side. The one I had was anyway.

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Re: 7" Touch Display; resistive touch not working

by mmoralls on Mon Jan 13, 2020 1:53 pm

Hi again,

Thanks for the help; I won't be using a stylus. I'd like to stick with the screen I purchased and think I just have to get the touchscreen part to work. I managed to change a setting in the config.txt file which allows me to power the screen through one of the USB ports. So my next question is: could I combine 2 of the ports into the one power cable to the driver board?

Thanks!

mmoralls
 
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Re: 7" Touch Display; resistive touch not working

by alphanumeric on Mon Jan 13, 2020 3:47 pm

The Pi 3B has a 1.2A limit on the current that can be drawn from the USB ports. Thats 1.2A shared by all 4 ports. Using a splitter cable won't help as you can draw that 1.2A all from one USB port. And I'm guessing that config.txt edit was the max usb current entry? That has no effect on a Pi 3B as its already at 1.2A.
https://www.raspberrypi.org/documentation/faqs/#pi-power
For any hope of this working your going to want to be using the official 2.5A Pi power supply. It's what I used with my touch screens.

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Re: 7" Touch Display; resistive touch not working

by mmoralls on Tue Jan 14, 2020 12:42 pm

Thanks for the help sir! I wondered if I could proceed a little further with this and any additional advice you might have with what I have done so far.

I am now using the power supply that came with the Pi vs. the one I was using for the hifi amp that I added and everything seems to working fine with sound and display but the touchscreen part still doesn't work. The only change I made as far as the display in the config.txt is uncommenting
Code: Select all | TOGGLE FULL SIZE
hdmi_force_hotplug=1
.

I tried a couple more display configurations in the config.txt but no difference.

ignore_lcd=1
display_default_lcd=0

If you have no other suggestions at this point then I guess I bought this display without doing enough research and will have to buy one that is known to work.

Thanks again!

mmoralls
 
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Re: 7" Touch Display; resistive touch not working

by alphanumeric on Tue Jan 14, 2020 2:25 pm

I don't have any other suggestions on how to get the touch part working. I will say that, as far as I know, none of those config.txt entries have anything to do with touch, they only affect the display portion of the screen.

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Re: 7" Touch Display; resistive touch not working

by adafruit_support_mike on Wed Jan 15, 2020 5:54 am

PID 2396 comes with an AR1100 touchscreen controller breakout. It connects to the 4-line flex cable coming out of the display and the RasPi's USB port. Once the connections are made, it should look like a generic mouse.

Post a photo showing your hardware and connections and we'll take a look.

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Re: 7" Touch Display; resistive touch not working

by mmoralls on Wed Jan 15, 2020 12:47 pm

Ok, so am I missing one more connection?

Thanks!
Attachments
IMG_20200115_112901.jpg
IMG_20200115_112901.jpg (667.16 KiB) Viewed 79 times

mmoralls
 
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Re: 7" Touch Display; resistive touch not working

by alphanumeric on Wed Jan 15, 2020 3:51 pm

Yes, you need to connect a USB cable from the Pi to the small board hanging below the screen. The one on the long thin ribbon cable.

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Re: 7" Touch Display; resistive touch not working

by mmoralls on Wed Jan 15, 2020 10:44 pm

Argh, I'm such a dufus! I just turned the board over and see the writing on the back. What is the USB type on the AR1100?

Thanks for all your help!

mmoralls
 
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Re: 7" Touch Display; resistive touch not working

by adafruit_support_mike on Thu Jan 16, 2020 1:26 am

It's a USB-2 device. Use any USB-A to micro-B cable and it should work.

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Re: 7" Touch Display; resistive touch not working

by mmoralls on Thu Jan 16, 2020 6:18 am

Thanks again!

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