20x4 I2C LCD Startup external power issue

Hello,

I will start by saying if I power my project via USB the screen works great. Once I connect my project to an external power source the screen doesn't initialize and just displays boxes until I press the reset button then the sketch works correctly.

I am using an Arduino DUE

Has anyone else had this issue? If so what did you do to fix it?

What Arduino board are you using? How are are you powering the LCD module? How do you connect the external power source and what is the voltage of that power source? What are the power voltages seen by the LCD module for the two configurations?

--- bill

I had the same problem :slightly_frowning_face: . I just push the restart button ::) . You could have an on switch (idea, not tested), where you connect a button to the reset pin and gnd, connect the wire that goes to 5v from the lcd to a pin, and in the beginning of the code, give power to the pin. That way, the lcd will be off, you plug it in, it is off because it doesn't start the code till you press reset, and the push the button, and it starts the code, turns the lcd on, and works. Like a TV, it can be plugged in and still be off.