LCD 20x4 Display I2C Interface
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Overview
The DIYables LCD 20x4 Display with I2C Interface offers 80 characters across 20 columns and 4 rows, connected via a simple 4-wire I2C bus. The blue backlight with white characters provides excellent readability, and the built-in potentiometer allows contrast fine-tuning. Software can toggle the backlight on or off for power management. Compatible with 5V and 3.3V microcontrollers via I2C.
Quick Overview
| Property | Value |
|---|---|
| Display Format | 20 characters × 4 rows |
| Total Characters | 80 |
| Interface | I2C (4-wire) |
| Supply Voltage | 5V |
| Backlight Color | Blue |
| Character Color | White |
| Contrast Control | Potentiometer |
| Backlight Control | Programmable ON/OFF |
Key Features
80-Character Capacity
Four rows of 20 characters give far more display real-estate than a standard 16×2, suitable for menus, sensor dashboards, and multi-line status readouts.
I2C — Minimal Wiring
Only VCC, GND, SDA, and SCL required, leaving nearly all GPIO pins free on the microcontroller.
Blue Backlight with White Text
High contrast between the blue background and white characters ensures readability in varied lighting conditions.
Programmable Backlight
Backlight can be switched off in code to save power in battery-operated applications.
Technical Specifications
| Parameter | Value |
|---|---|
| Display Type | Character LCD |
| Layout | 20 columns × 4 rows |
| Total Characters | 80 |
| Interface | I2C (4-wire) |
| Supply Voltage | 5V |
| Backlight | Blue LED with white text |
| Contrast Control | Built-in potentiometer |
| Backlight Control | Programmable ON/OFF |
Pinout
| Pin | Label | Description |
|---|---|---|
| 1 | VCC | Power supply (5V) |
| 2 | GND | Ground |
| 3 | SDA | I2C data line |
| 4 | SCL | I2C clock line |
Power
Requires 5V on VCC. I2C signal lines can be driven from 3.3V or 5V microcontrollers — the PCF8574 backpack tolerates both. Typical backlight current is 60–80 mA; with backlight off, current drops to ~2 mA.
Getting Started
Wiring (Arduino Uno)
| LCD Pin | Arduino Pin |
|---|---|
| VCC | 5V |
| GND | GND |
| SDA | A4 |
| SCL | A5 |
Libraries
Applications
- Multi-line sensor dashboards
- Menu and settings navigation
- Serial terminal / debug output
- Weather station displays
- Industrial status panels
- Home automation interfaces
Equivalent Boards
| Module | Key Difference |
|---|---|
| LCD I2C 16x2 | Smaller, 32 characters — same protocol and library |
| LCD 2004 I2C Blue Backlight | Same size, blue backlight specific product |
| LCD I2C 2004 Green/Yellow | Same size, green/yellow backlight |
| OLED 128x64 | Graphical, self-emitting, smaller pixel-based display |
Beginner Tutorials
Notes
- If the I2C address is unknown, run an I2C scanner sketch to detect it.
- Contrast potentiometer: turn counterclockwise if only black squares appear.
- The library function lcd.begin() is not needed — use lcd.init() for LiquidCrystal_I2C.
- Check I2C address — some 20x4 modules use 0x3F instead of 0x27.
Community
Revision History
| Version | Date | Notes |
|---|---|---|
| v1.0 | 2026-06 | Initial entry |