Power drain, contrast control


I just bought the WH2004A, 20x4 LCD display. Do I need to connect a pot in order to adjust the contrast? What if I don't connect any pot?

And can I power the LCD from the Nano or will it fry the board?


You have to connect pin 3, but you don't have to use a potentiometer. Many displays work adequately with pin 3 connected to GND. Otherwise you can try various resistors, typically 1K or less, between pin 3 and GND.

Yes you can power the LCD from the Nano. The backlight is a different question, but may be OK as well, depending on it's current requirements.


You mean, will the backlight current fry the board, or can I disable that backlight?

Your questions cannot be really answered without knowing how you are powering your Nano, what else you have connected to the Nano I/O pins, whether or not your display actually requires a backlight to be visible, how much current your backlight requires etc.


During tests, I usually power the Nano (or any board) through the USB cable.