I am trying to connect Grove 16x2 LCD (White on Blue) to my Arduino uno rev 2 wifi. So far, I've tried hd44780 library's ioClass examples, but nothing worked. I've then decided to scan ports and when LCD was connected to rev 2 SDA/SCL pins I've got (Unknown error at address 0x3E). So it recognizes that something is connected, but doesn't recognize the LCD. I've also tried to run I2CexpDiag, which also returned "Unknown error at address 0x3E". I tried the same LCD with Arduino UNO and mkr1010, both work flawlessly. I've also tried connecting the SDA/SCL pins to A4/A5, but nothing there either. Any ideas what could be the problem?

  • 1
    wiki.seeedstudio.com/Grove-16x2_LCD_Series > Step 1. Download the Grove-LCD RGB Backlight Library from Github.
    – Juraj
    Feb 9, 2023 at 10:47
  • 1
    Just tried it, tried a couple of examples, but nothing comes up on the screen.
    – MelaNChoLy
    Feb 9, 2023 at 11:01
  • Uno WiFi has some on-board I2C devices. run the I2CScanner sketch
    – Juraj
    Feb 9, 2023 at 12:09
  • Yes, it does recognize something on 0x60
    – MelaNChoLy
    Feb 9, 2023 at 14:22
  • 2
    Yea, like I've mentioned, I get an error "Unknown error at address 0x3E", which is the address of the LCD. However the LCD works with other boards flawlessly
    – MelaNChoLy
    Feb 9, 2023 at 15:44


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Browse other questions tagged or ask your own question.