I am working on a project with a Teensy 3.5 and I would like to make a hand held controller with an ILI9341 display and rotary encoder connected by a 3' - 6' cable. On a breadboard my code works great with the ILI9341_t3.h and XPT2046_Touchscreen.h libraries. When I try to connect the display and the Teensy via a cable I only get a white screen - although touch seems to work.

I initially tried an HDMI cable using a pair of connector boards I found on Amazon, using AWG 22 wires soldered to the connector boards. When this didn't work I tried CAT6 cable using punch down connectors for 8 of the 9 connections (using GND on the breadboard) which also just displayed a white screen. Perhaps there is some basic reason why this does not work with the cable length I am attempting or perhaps I have an error in the connection.

The photo attached shows the setup with both sets of wires attached: 1) basic jumpers from the display to the Teensy; 2) Cat6 wire from each component to a Keystone jack. After the CAT6 didn't work I disconnected the patch cable and put jumpers back on to confirm that everything else was working. I did check connectivity between the display header and the Teensy header for each connection which looked to be correct for the CAT6 setup.

I don't expect forum readers to look at this image and figure out which wire might be in the wrong place, but please let me know if I'm headed in the right direction. Any thoughts or advice are most welcome - many thanks in advance.

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