A while ago, I bought a couple of the new Raspberry Pi 3’s and at the same time, bought a 7″ touch screen and a housing (which was on special) for it from element14.
As usual, there can be a delay between purchase and actually assembly or use, due to other commitments. Anyway, a couple of nights ago, I decided to assemble the Raspberry Pi with the touchscreen. The touchscreen was pre-assembled, so all that I had to do was to attach the screen cable to the Raspberry Pi 3, then connect the four wires to provide power and the data signals to the touchscreen controller board. By the way, the instructions did not say that the SDA and SCL signals had to be connected and showed only connecting the ground and +5V pins.
I also needed to download the latest Raspbian operating system, and copy the image to a micro-SD card which I did the next day. Then finally plugging in the card, and fastening the Raspberry Pi down with four tiny screens. Next was placing all this in the housing. All went together and I connected up a suitable power supply and powered up.
Voila! Hmm, the display is upside down – ok, and the touchscreen wasn’t working. Checking out the FAQ on the appropriate sites indicates a fix for the display – to rotate by 180 degrees in the /boot/config.txt then a check to see if the touchscreen hardware was seen by the OS. Yes, the drivers are active so what is going on? I decided that it was time to open it up and check the touchscreen cable.
To my surprise the cable was disconnected and sticking up at a right angle – then the penny dropped. Putting the case on, must have disconnected the cable, which was connected, but now is not.
This is the touchscreen cable, the one that is attached to that black square chip – the cable is a little bent at the edge which meant that something was pressing on it. Turning the back of the case around showed me the problem.
The cutout for the touchscreen cable has a sharp edge, which was pressing down on the edge of the touchscreen assembly with the chip on it, and since the thinner cable is not that long, pushing down on it would pull that thin cable out. Which is what must have happened. I measured the distance from the edge of the case to that touchscreen assembly, then marked on the case where I needed to remove that sharp edge. I got out my trusty file which happened to be almost the right width at the area I needed to file out, and proceeded to remove some plastic material making that marked area more rounded which would reduce the pressure on that assembly.
Here is the final result. After careful reassembly and checking of the cable which was can just see through slots in the casing for the HDMI socket, I can confirm that the touchscreen cable is still attached.
After powering up, I now have touch!