Part

Character LCD, 20x4

Four rows of twenty on the same controller as the 16x2. Text that runs off row 0 carries on in row 2.

16 pins
In 1 project
In 1 lesson

Drawn live by the editor's own code, at the size you see it.

At a glance

The Character LCD, 20x4 in brief

What it is, and where it sits on the bench.

The LCD2004 is the 20x4 character LCD with the bare sixteen-pin header, VSS, VDD, V0, RS, RW, E, D0 to D7, A and K, on the same HD44780 controller as the 16x2. Unlike the lcd2004i2c, it has no PCF8574 backpack and no address. It is a 5 V module. In four-bit mode it takes six signal wires, RS, E and D4 to D7, to any digital pins on an Uno, with RW tied to ground; an ESP32 can drive the same six from its 3.3 V pins while VDD stays on 5 V. Mokxi models the four-bit start-up, the byte taken on the falling edge of E, the busy time after every byte and after a clear, CGRAM, and the contrast: the drive is VDD minus V0, so V0 at ground is fully dark and a 10 k pot shows text only near its ground end. Four rows are the controller’s two 40-character lines, so the rows start at 0x00, 0x40, 0x14 and 0x54 and a long print runs off row 0 into row 2. Nothing is read back, there is no 5x10 font, and bias, temperature and viewing angle are not modeled.

Family: Displays
Pins: 16

Pins

16 pins

Named as the editor names them, so a wire lands where you expect it.

What it does

VSS

Ground.

VDD

Ground and 5 V.

Contrast. Near VSS is dark text; at VDD the glass is empty.

Low for a command, high for a character.

Tie it to ground: nothing here answers a read.

The clock. The byte is taken on the falling edge.

The backlight LED.

How to use it

How to use a 20x4 LCD with an Arduino, without I2C

Six signal wires in four-bit mode: RS to pin 2, E to 3 and D4 to D7 to pins 4 to 7. VDD goes to 5 V, and VSS, RW and V0 to GND, which puts the contrast at full. Create a LiquidCrystal with those six pins and call begin(20, 4): the 20 and the 4 are what give setCursor() the right row starts.

The controller has two lines of memory, not four, so the rows start at 0x00, 0x40, 0x14 and 0x54. In the project beside this, the bare panel prints forty characters in one go and the second twenty land in row 2, not row 1. If the glass is empty, look at V0: on a 10 k pot the text only shows near the ground end of the turn.

Part pin

Board pin

VSS

GND

VDD

5 V

GND

Pin 2

GND

Pin 3

Pin 4

Pin 5

Pin 6

Pin 7

LiquidCrystal compiles on every board here. With the backpack fitted it is the lcd2004i2c part instead, on two wires.

Arduino Uno: twenty by fourlive0.000 s 0.00x

Click to open it in the editor

This is the simulator itself, running here. Click anything to open it in the editor.

Open this project in the editor Read the full tutorial

Four rows on the bare 20x4 with LiquidCrystal

#include <LiquidCrystal.h>
LiquidCrystal lcd(2, 3, 4, 5, 6, 7);  // RS, E, D4 to D7
void setup() {
  lcd.begin(20, 4);
  lcd.print("Row 0");
  lcd.setCursor(0, 1);
  lcd.print("Row 1");
  lcd.setCursor(0, 2);
  lcd.print("Row 2 starts at 0x14");
  lcd.setCursor(0, 3);
  lcd.print("Row 3 starts at 0x54");
}
void loop() {}

How it is modeled

What is true about the Character LCD, 20x4, here

In its help article’s own words: what the simulation gets right, and where it stops.

Not modeled

The same as the 16x2: nothing is read back (the busy flag, the address counter and DDRAM all read nothing), there is no 5x10 font, and bias, temperature and viewing angle do not exist. On the backpack, the PCF8574's input port and its interrupt pin are not there either.

From 20x4 character LCD, in full.

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