LCD I2C QAPASS NOT WORK

Other Hardware Displays
1

HI ALL,
i found 2 type lcd i2c display:

  1. with marking QAPASS test with example coding "HELLO WORLD" = BLANK
  2. no marking test with "HELLO WORLD" = OK

QAPASS marking no R9 and no marking have R9

now anyone know how to use this QAPASS lcd?. i have 5 or 6pcs lcd like this.

PLS see photo

lcd i2c.jpg
lcd i2c.jpg799×329 84.1 KB

lcd test.jpg
lcd test.jpg800×242 43 KB

2

pls anyone can help..huhuhuhu

3

My guess would be that the backpacks are wired differently to the hd44780 display using different pin mappings so one works with the library you are using and one doesn't.
If you used my hd44780 library it will auto detect the pin mappings. It also includes a diagnostic to test the i2c signals and the backpack.
Run the diag tool and see what it says.