LCD without arduino

Using Arduino Project Guidance
1

Hello all,

Warning Rookie here

Is it possible to write on LCD screen with arduino and cut the connection to arduino while the screen still shows the message?

I use a I2C to control the LCD display;
SDA->A4
SCL->A5
VCC->5V
GND->GND

If I cut the connection to the A4 and A5, the message remains on the screen. But I couldnt use another power supply to show the message;

SDA->A4 (Arduino)
SCL->A5 (Arduino)
VCC->Battery
GND->Battery

so I could take the lcd and battery and disconnect it from the arduino to carry the message around. I know this can easily solved by 2 arduinos but I just wanted to know if it can be done just with external power source. Thank you

2

Which LCD? A character LCD like the 1602 or 2004 or something else?

3

Have a look at e-paper displays , they will do it

4

Connect the LCD to its own 5V supply.

Connect the Arduino to the LCD with only 3 wires, GND, SCL, SDA.

Use your program to write to the display.

Disconnect the 3 wires from the Arduino.

What happens ?

5

Depends on the LCD.

Most have their own driver IC, and the Arduino just sends the data that has to be show on the display to that driver IC. No new data = no change. So removing the Arduino does not affect such a display, any info shown will remain.

6

srnet:
Connect the LCD to its own 5V supply.

Connect the Arduino to the LCD with only 3 wires, GND, SCL, SDA.

Use your program to write to the display.

Disconnect the 3 wires from the Arduino.

What happens ?

Well. That did it. Thank you very much!! I didnt guessed the GND should be connected to the arduino.

7

As a rule of thumb: grounds should ALWAYS be connected, as that provides the reference potential (by convention called the 0V level). There are very few exceptions to this rule, and those usually revolve around the use of optocouplers and wanting to keep circuits completely electrically separated.