Hello,

I tried use my old lcd which only accepts 3 wire(STR, CLK, DATA) 5V logic (source code, schematic)
I tested 5V arduino mcu, works well but the problem is that I want to use 3.3V mcu. so I have to use logic level shifter

signal oscillate sometimes like below. what should I check?
Yellow => strobe
blue => data
pink => clock





here is wiring diagram
(color legend is same as scope)


thank you for reading my post

 

Isn't that your data? The data rate is too high to be seen at that timebase setting.