weird oscillating between 3.3V <-> 5V logic level shifter

Thread Starter

luxflow

Joined Jul 12, 2021
1
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

DS1Z_QuickPrint6.png

DS1Z_QuickPrint8.png

here is wiring diagram
(color legend is same as scope)
1626069602171.png

thank you for reading my post
 
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