Arduino for Beginners · Sensors, I2C/SPI buses and the final project
LCD/OLED display over the I2C bus
Sensors, I2C/SPI buses and the final project
Introduction
The I2C bus lets you connect a display to Arduino using just two signal lines instead of a dozen, as in a classic parallel LCD. This lesson shows how I2C works (SDA, SCL, 7-bit addressing, master-slave mode, pull-up resistors), how to drive a character LCD with a PCF8574 converter (LiquidCrystal_I2C library) and a graphical SSD1306 OLED (Adafruit_SSD1306 or U8g2), and how to diagnose common faults: wrong address, address conflict, missing Wire.begin(), or a forgotten display.display().