16x2 I2C LCD Interface

Custom Bus Configuration

To optimize PCB and jumper routing, the I2C bus is bound to custom GPIOs instead of the ESP32 defaults (GPIO 21/22):

• SDA: GPIO 17
• SCL: GPIO 19
• I2C Address: 0x27

Wire.begin(LCD_SDA_PIN, LCD_SCL_PIN);
lcd.init();

Screen Layout Matrix

Row 0: [G][a][s][:][ ][1][4][5][ ][T][:][2][3][.][8]
Row 1: [H][:][4][8][.][2][ ][ ][ ][M][:][1][ ][ ][1][8]

• Line 1: Real-time Gas measurement followed by Temperature in °C.
• Line 2: Relative Humidity %, Motion flag (1 active, 0 idle), and the 20-second sleep countdown timer (18, 17, … 00).