16x2 LCD with LiquidCrystal library in Arduino - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output on the LCD?

Consider this Arduino code using the LiquidCrystal library to display text on a 16x2 LCD. What will appear on the LCD screen after running this code?

Arduino

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  lcd.begin(16, 2);
  lcd.print("Hello, World!");
  lcd.setCursor(0, 1);
  lcd.print("LCD Test");
}

void loop() {}

A First line: (empty)\nSecond line: Hello, World! LCD Test

B First line: LCD Test\nSecond line: Hello, World!

C First line: Hello, World! LCD Test\nSecond line: (empty)

D First line: Hello, World!\nSecond line: LCD Test

💡 Hint

Remember that lcd.setCursor(col, row) sets the position for the next print.

The lcd.print("Hello, World!") prints on the first line starting at column 0. Then lcd.setCursor(0, 1) moves the cursor to the start of the second line, where lcd.print("LCD Test") prints the second line.

🧠 Conceptual

intermediate

What does lcd.begin(16, 2) do?

In the LiquidCrystal library, what is the purpose of the lcd.begin(16, 2) command?

A It initializes the LCD with 16 columns and 2 rows, setting up the display size.

B It clears the LCD screen and turns off the backlight.

C It sets the cursor to the first column and first row.

D It loads a custom character set into the LCD memory.

💡 Hint

Think about what parameters begin() takes and what the LCD needs before printing.

The lcd.begin(16, 2) command tells the library the LCD size is 16 columns wide and 2 rows tall. This prepares the LCD to display text correctly.

🔧 Debug

advanced

Why does this code not display anything?

Look at this Arduino code snippet. Why does the LCD remain blank after uploading?

Arduino

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  lcd.print("Hello");
  lcd.begin(16, 2);
}

void loop() {}

A Because <code>lcd.begin()</code> must be called before any <code>lcd.print()</code> calls to initialize the display.

B Because the <code>loop()</code> function is empty and must contain <code>lcd.display()</code>.

C Because the pins are incorrectly assigned and need to be changed.

D Because the LCD backlight is off and must be turned on manually.

💡 Hint

Think about the order of initialization and printing.

The lcd.begin() function must be called before printing anything. It sets up the LCD hardware. Calling lcd.print() before lcd.begin() does nothing because the LCD is not ready.

📝 Syntax

advanced

Which code snippet correctly sets the cursor and prints on second line?

Which of the following code snippets correctly moves the cursor to the start of the second line and prints "Ready" on a 16x2 LCD?

A

lcd.setCursor(0, 2);
lcd.print("Ready");

B

lcd.setCursor(1, 0);
lcd.print("Ready");

C

lcd.setCursor(0, 1);
lcd.print("Ready");

D

lcd.setCursor(1, 1);
lcd.print("Ready");

💡 Hint

Remember that row numbering starts at 0.

Row 0 is the first line, row 1 is the second line. Column numbering also starts at 0. So lcd.setCursor(0, 1) moves to the first column of the second line.

🚀 Application

expert

How many characters fit on a 16x2 LCD and what happens if you print more?

You have a 16x2 LCD connected and initialized with lcd.begin(16, 2). How many characters can you display at once? What happens if you print a string longer than that?

A You can display 32 characters total. Printing more characters will overwrite the first line repeatedly.

B You can display 32 characters total. Printing more characters continues printing off-screen and they are lost (not visible).

C You can display 16 characters total. Printing more characters causes the LCD to reset.

D You can display 32 characters total (16 per line). Printing more scrolls the text horizontally on the first line only.

💡 Hint

Think about how the LCD handles text longer than its display size.

A 16x2 LCD can show 16 characters on each of its 2 lines, totaling 32 visible characters. If you print more than 32 characters, the extra characters are sent to the LCD memory but are not visible because the display does not scroll automatically. They are effectively lost unless you manually scroll or reposition the cursor.