What is the problem?
Raspberry Pi 3 B+ and Ender 3 Pro 1.1.4 main board are not talking to each other. It had been working fine for a couple weeks and then the Pi quit recognizing the printer.
I have exhausted my limited knowledge of the Pi but have tried several of the proposed fixes I have read on threads.
What did you already try to solve it?
I have tried 3 different USB cables.
The P3B+ is powered from the printer PSU through a buck converter. I checked the buck converter and it is adjusted correctly to 5V.
I have tried the tape over the 5V pin on the USB cable and it still does not work.
I have re-flashed the Ender 3 Pro main board and reloaded Octoprint on the P3B+.
I can plug a USB drive into the P3B+ and it recognizes it, so I believe the P3B+ USB ports are good.
I can power off the printer, plug in my laptop to the USB port on the main board and it powers the LCD and my laptop can see the board, so I believe the USB on the mainboard is good.
Additional information about your setup
Ender 3 Pro Creality 3D V1.1.4