2004 20x4 I2C Character LCD Display Module (Blue Backlight)

A bigger text display with an easy interface

This 2004 (20 x 4) character LCD module gives four lines of twenty characters each, which is enough room for a small menu, several sensor readings or a short message at once. An I2C adapter is soldered to the back, so the module can be interfaced with a microcontroller using just two signal wires.

It is described as a fully assembled and tested serial LCD 20 x 4 module, and it is a low-power consumption character LCD with a built-in controller, well suited to Arduino-based projects.

Wiring and use

The interface is I2C at 5 V, with the address either 0x27 or 0x3F depending on the unit you receive, so it is worth running an I2C scanner sketch the first time. The pins are GND, VCC, SDA and SCL, and contrast is set with an onboard potentiometer.

Install an I2C LCD library, set it to 20 columns and 4 rows and the address you found, then print your first message. If nothing shows, adjust the contrast trimmer before assuming the display or the address is wrong.

Who it is for

Makers who have outgrown a 16x2 display and want more room for menus, logs or several values on screen at the same time.

Care and troubleshooting

Handle the module by its edges rather than pressing on the LCD glass, and clean the screen only with a soft dry cloth. If the display shows a full row of black blocks, the contrast is set too high; turn the trimmer the other way. Keep it away from strong static, since the driver IC on the back can be sensitive to it.

Questions buyers ask

How many characters does it show?

Twenty characters across four lines.

What interface does it use?

I2C, at address 0x27 or 0x3F.

What voltage does it need?

5 V.

How many wires does the I2C version need?

Two signal wires (SDA and SCL), plus power and ground.