If you bridge these pads, it grounds that address line. There are 3 address jumper locations marked A0, A1, A2. If you need to adjust I2C address to avoid a conflict, this can be done on the I2C adapter board on the back of the module. The address is marked on the bag that the module comes in. The default I2C address for these displays is 0x27. The I2C interface is a daughter board attached to the back of the LCD module. This display incorporates an I2C interface that requires only 2 pins on a uC to interface with and it has good library support to get up and running fast. At 5V, the backlight draws about 30mA, so it should also be possible to drive it with a PWM pin off a uC to allow the display to be dimmed via software if desired. It is not known what the safe upper limit is for driving the LCD backlight so it is probably best not to exceed 5V by too much. The backlight can go down to about 3V before it goes out. That jumper can be removed and a voltage applied to the header pin nearest the ‘LED’ markings on the board to provide power to the backlight separately. The backlight intensity is not directly controllable though the I2C interface, however there is a jumper on the I2C board that supplies power to the backlight. The backlight has a potentiometer for adjustment of the contrast of the display for best viewing. Each of the characters are composed of a 5 x 8 dot matrix for good character representation.

The display is composed of a 20 character x 4 line LCD display with a blue backlight and white characters.

For an interactive display, pairing this type of display with a rotary encoder to navigate and select menu items on the display can provide a very nice user interface. These displays are straightforward to use and are a great way to provide a user interface on many projects where you need more info than simple LED indicators or 7-Segment displays can provide since these are full alphanumeric displays with 4 lines of 20 characters each for a total of 80 characters which is a fair amount of info. Adjustable backlight intensity and contrast.KEY FEATURES OF LCD2004 20×4 I2C BLUE LCD DISPLAY : The LCD2004 20×4 I2C Blue LCD Display provides a 20 character x 4 line LCD with I2C interface for easy control by a uC.

20x4 lcd library fritzing part