Last time, we looked into using a logic analyzer to decode SPI signals of LCD displays ... on the kind of interface you’re sniffing, be it I2C, UART or SPI, you will get five to ten lines ...

Getting a character LCD ... 3.3V logic. You could use a level converter (you’d need at least 7 pins to be converted in this case) or you can be a bit more clever. [Tech2077] grabbed an I2C ...

To link a standard 16×2 LCD directly with the microcontroller, for instance Arduino, you would need atleast 6 I/O pins to talk to the LCD. However, if you use an LCD module with I2C interface ...