Tested LCD interface

I had one RAMPS discount full graphics controller laying around from my RigidBot. I did use it with the original controller and decided to test it with the PrntrBoard.

In Rev1 and Rev2 of the board I did not have enough pins on the LCD connector to be able to use all buttons on the panel. In the Rev3 I used every last pin of the tiny 64-pin package and I just got enough (or so I thought).

I learned the SPI used by the LCD panel is not very standard and had to fight with Marlin to make the TMC drivers and the LCD co-exist on the same SPI bus.

Finally I was able to use the panel:

One of the pins I used for the button input did not quite cooperate, so I have only one button + the rotary controller for the UI. Lucky for me both Marlin and Smoothieware were functioning with that configuration.

I had to disable the TMC diver monitoring, because the LCD controller was getting confused by the SPI communication with the TMC drivers. I think I can create a small breakout board with a few AND gates to alleviate this interference.

Here is a video of the panel working in Smoothieware:


2 Replies to “Tested LCD interface”

  1. The RepRap Full Graphic LCDs (ST7920) don’t need SPI for the display. I’m using one with Klipper connected to random GPIO pins on an Arduino Due.

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