Help ! I2c LCD screen using STM 32 Nucleo F303RE


I purchased a 20x4 LCD with an I2C module off of ebay and am trying to get a basic “hello world” displayed on it. I have been able to get it to work using a PIC microcontroller in the past but I was using all the pins in 8 bit configuration rather than through I2C. I used an arduino code to find the correct address for the module (0X27) . I believe I have the correct LCD library downloaded, and the ports are connected correctly to SDA,SCL,5V, and GND. When I upload the code shown in the picture ,nothing is displayed on the LCD. I have tried changing the contrast but no text was displayed. Does anyone have any suggestions or see any problems with what I did? I may consider purchasing a new lcd/i2c module if this seems to be a hardware issue. I included the link to the screen I purchased below.

20x4 LCD I2C

Doesn’t Arduino use 7 bit address? Mbed API uses 8 bit address. So, you may want to try 0x27 << 1 (which is 0x4E).

That, Is a good point, I hadn’t thought of that. I tried your suggestion and it is causing the 2nd and 4th row to move a bright and dim pattern but unfortunately I still don’t see any characters @lonesometraveler


the TextLCD has also a config file called TextLCD_Config.h and its settings can have an impact on it. Especially the content starting at line 66.
You can also check this topic for some inspiration

BR, Jan