ldr and lcd
// C++ code #include <LiquidCrystal_I2C.h> int ldr_light = 0 ; int darkness = 0 ; LiquidCrystal_I2C lcd_2 ( 0x 27 , 16 , 2 ) ; void setup () { lcd_2 . init () ; lcd_2 . clear () ; lcd_2 . backlight () ; pinMode ( A0, INPUT ) ; pinMode ( 7 , OUTPUT ) ; darkness = 650 ; } void loop () { ldr_light = analogRead ( A0 ) ; lcd_2 . setCursor ( 1 , 0 ) ; lcd_2 . print ( "Is it dark ?" ) ; lcd_2 . setCursor ( 1 , 1 ) ; lcd_2 . print ( "darkness=" ) ; lcd_2 . print ( ldr_light ) ; if ( ldr_light < darkness ) { digitalWrite ( 7 , HIGH ) ; } else { digitalWrite ( 7 , LOW ) ; } delay ( 1000 ) ; // Wait for 1000 millisecond(s) lcd_2 . clear () ; } https://www.build-electronic-circuits.com/arduino-light-sensor/