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17. 3月 2026

Using an LCD — SIK Circuit 15

Display text on a 16x2 character LCD. Learn about the LiquidCrystal library, HD44780 displays, cursor positioning, and creating a real-time seconds counter.

手順

Parts & Introduction

A 16x2 character LCD can display 2 rows of 16 characters each. Using Arduino's LiquidCrystal library, you can display text, numbers, and custom characters. This is the HD44780 standard used by most character LCDs.

Parts Needed

1x Arduino Uno + USB cable
1x Breadboard
1x 16x2 Character LCD
1x Potentiometer (for contrast adjustment)
16x Jumper Wires

このステップの材料:

SparkFun Inventors Kit - V3.21 キット

Arduino Uno R31 個

Breadboard1 個

16x2 Character LCD1 個

Potentiometer (10K)1 個

Jumper Wires16 個

必要な工具:

Computer with Arduino IDE

Hardware Hookup

Wiring Instructions

The LCD has 16 pins. Pin 1 is closest to the corner of the board.

LCD Pin	Connection
1	GND
2	5V
3	Potentiometer wiper (contrast)
4	Arduino Pin 12 (RS)
5	GND (R/W)
6	Arduino Pin 11 (Enable)
7-10	Not connected
11	Arduino Pin 5 (D4)
12	Arduino Pin 4 (D5)
13	Arduino Pin 3 (D6)
14	Arduino Pin 2 (D7)
15	5V (backlight +)
16	GND (backlight -)

Connect the potentiometer: one side to 5V, other to GND, center pin to LCD pin 3 for contrast adjustment.

このステップの材料:

16x2 Character LCD1 個

Potentiometer (10K)1 個

Breadboard1 個

Jumper Wires16 個

Arduino Code

Open the Arduino IDE and upload the following sketch to your Arduino board.

lcd_display.inoarduino

/*
SparkFun Inventor's Kit
Example sketch 15 — LIQUID CRYSTAL DISPLAY (LCD)

Display "hello, world!" and a seconds counter on a 16x2 LCD.

Hardware connections:
  LCD pin 1 to GND, pin 2 to 5V
  LCD pin 3 to potentiometer center (contrast)
  LCD pin 4 to Arduino pin 12 (RS)
  LCD pin 5 to GND (R/W)
  LCD pin 6 to Arduino pin 11 (Enable)
  LCD pins 11-14 to Arduino pins 5,4,3,2
  LCD pin 15 to 5V, pin 16 to GND

This code is completely free for any use.
*/

#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup()
{
  lcd.begin(16, 2);
  lcd.clear();
  lcd.print("hello, world!");
}

void loop()
{
  lcd.setCursor(0, 1);
  lcd.print(millis() / 1000);
}

このステップの材料:

Arduino Uno R31 個

必要な工具:

Computer with Arduino IDE

Test & Experiment

What You Should See

"hello, world!" appears on the first line of the LCD. The second line shows a running counter of seconds since power-on. You may need to twist the potentiometer to adjust contrast until text is visible.

Troubleshooting

Screen blank or solid blocks: Adjust the potentiometer until you see text. The contrast range is narrow.
Nothing at all: Verify the LiquidCrystal library is included and all 16 wires are connected correctly.
Flickering: Check breadboard connections — loose wires cause display glitches.

Experiments to Try

Display the temperature sensor reading (from Circuit 7) on the LCD instead of the Serial Monitor.
Use lcd.setCursor(col, row) to place text at specific positions.
Create custom characters with lcd.createChar() for icons and symbols.
Display messages from serial input — type on your computer, see it on the LCD.