nothing it just blinks 1 time and then goes black
Yes! It is like that and then the message comes on the LCD.
Check the connection of the I2C Bus. SDA line of LCD should go at A4, and SCL line of LCD should go to A5 of the Arduino (UNO). After running the program, slowly rotate the contrast pot (min to max) located on the small IO board back on the LCD. Also check that backlight jumper is ON.
If you have another I2CLCD, connect that one and check the functionality.
BTW; Have you added the line lcd.begin(16, 2); in the program that I have provided you. It should not be there. Please, remove this line and execute the program. The constructor (lLiquidCrystal_I2C lcd(0x3F, 16, 2);) has taken care of it.
Also, the lcd.init(); is not there! Who has removed this line from the program? Please, add this line in the program. The program is like this:
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x3F, 16, 2);
void setup()
{
lcd.init();
lcd.backlight();
lcd.setCursor(0, 0); //DP0 of Top Line
lcd.print("Hello!");
}
void loop()
{
}
Copy the above program in your IDE and upload unchanged.