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I purchased this circular touchscreen on Alibaba to use with a Raspberry Pi in my prototype. I told the manufacturer I was using a Pi and the screen does not connect to the Pi by default as it has a MIPI connector, OK no problem so they sold me this HDMI adapter and even gave me some helpful code to get the screen working on the Pi. However they did not mention that they provided no solution for getting the touch part of the touch screen working (or even connected) and basically stopped responding once I mentioned this...

So, I currently have a working (and honestly pretty impressive res.) screen but no touch functionality and really need some help getting this working as I have no idea where to start.

The documentation refers to this component as the "CTP" which yielded no search results for me. The doc only mentions this component 1 time for this pinout

CTP Pinout

And then in the mechanical drawing it mentions that the connector is (OK-22M010-04) and pairs with (OK-22F010-04) and then literally no other mentions of the component in the documentation.

I am looking for any and all recommendations to get this thing working, is it even reasonably possible?

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  • Unlikely without a proper documentation and/or a significant reverse engineering effort. – Dmitry Grigoryev Jul 10 '19 at 6:49
  • Looks like basically an I2C interface (SDA, data, + SCL, clock). "NC" is not connected. The voltages are not directly compatible with the Pi, but you should be able to use a level shifter with the data connections and perhaps a voltage divider or proper converter for the power (VCC) lines. The big, big, big issue is then the protocol spec, for which you definitely need a datasheet or some example code. – goldilocks Aug 13 '19 at 18:53
  • Did you ever get this sorted out? I am in the same position right now and I'm debating hiring a freelancer to build the board. Perhaps we could pool resources. – joshbg2k Apr 11 '20 at 21:36
  • No it is honestly highly complex and as far as I can tell basically the manufacturer has only gotten it working once on a bench. I found a way around needing the touch for my application so it works but I'm not really thrilled. If you hire a freelancer I would strongly advise finding one that has worked with display tech specifically. The manufacturer offered to build a custom one for me a while back but then rescinded it so as far as I'm concerned it basically doesn't work/is untested. Sucks because its so great otherwise. – Mason Newitt Apr 12 '20 at 22:08
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Maclight display could provide the total HDMI driving solution for the 3.4" round tft with capacitive touch, so you don't need to search the CTP connector for the touch screen. it is easier to use. Both round lcd and CTP could be drived through HDMI port. see here: https://www.szmaclight.com/product/3-4-inch-round-lcd-display-tft-800-800.html

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