LCD2004 20X4 Green LCD Display Module With I2C Serial Adapter

The LCD2004 20X4 Green LCD Display Module with I2C serial adapter is composed of a 20 character x 4 line LCD display with a blue backlight and white characters. Each of the characters are composed of a 5 x 8 dot matrix for good character representation.

The backlight has a potentiometer for adjustment of the contrast of the display for best viewing.

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. 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 can go down to about 3V before it goes out. 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. 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.

I2C Interface

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. The I2C interface is a daughter board attached to the back of the LCD module.

The default I2C address for these displays is 0x27. The address is marked on the bag that the module comes in.

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. There are 3 address jumper locations marked A0, A1, A2. Normally these lines are pulled high. If you bridge these pads, it grounds that address line. If you were to bridge all 3 to ground, the address would be 0x20. The range of all possible addresses spans from 0x20 to 0x27

KEY FEATURES OF LCD2004 20X4 GREEN LCD DISPLAY MODULE WITH I2C SERIAL ADAPTER:

• 20 character x 4 line Blue LCD
• I2C interface
• Adjustable backlight intensity and contrast
• 5V operation

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. 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.

Module Connections

Connection to the display is via a 4 pin header.

1 x 4 Header

• GND = Connect to system ground. This ground needs to be in common with the uC.
• VCC = Connect to 5V. This can come from the uC or be a separate power supply.
• SDA = Connect to the I2C / SDA pin on the uC.
• SCL = Connect to the I2C / SCL pin on the uC.

A red LED on the I2C interface board lights when power is applied.