16x2 LCD with LiquidCrystal library in Arduino - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the '16x2' mean in a 16x2 LCD?

It means the LCD has 16 columns and 2 rows, so it can show 16 characters per line and has 2 lines in total.

beginner

What is the purpose of the LiquidCrystal library in Arduino?

The LiquidCrystal library helps you control LCD screens easily by providing commands to display text, clear the screen, and move the cursor.

beginner

How do you initialize a 16x2 LCD using the LiquidCrystal library?

You create a LiquidCrystal object with the pins connected to the LCD, then call lcd.begin(16, 2) to set the size.

beginner

What does the command lcd.setCursor(0, 1) do?

It moves the cursor to the first column (0) of the second row (1) on the LCD, so the next text will start there.

beginner

How do you print 'Hello' on the LCD using LiquidCrystal?

Use lcd.print("Hello"); after setting the cursor position to display the text on the screen.

What is the correct way to start using a 16x2 LCD with LiquidCrystal?

A lcd.begin(16, 2);

B lcd.start(2, 16);

C lcd.init(2, 16);

D lcd.open(16, 2);

lcd.begin(16, 2); sets the LCD size to 16 columns and 2 rows, which is required before printing.

Which command clears all text from the LCD screen?

A lcd.clear();

B lcd.reset();

C lcd.erase();

D lcd.clean();

lcd.clear(); removes all text from the screen and resets the cursor to the home position.

If you want to print text on the second line, which cursor position should you use?

A lcd.setCursor(1, 1);

B lcd.setCursor(0, 1);

C lcd.setCursor(1, 0);

D lcd.setCursor(0, 0);

Rows start at 0, so the second line is row 1. Column 0 is the first character position.

Which library do you include to use a 16x2 LCD in Arduino?

A #include <LCD.h>

B #include <Display.h>

C #include <LiquidCrystal.h>

D #include <Screen.h>

LiquidCrystal.h is the official Arduino library for controlling LCDs.

What does lcd.print("Hi") do?

A Turns off the LCD.

B Clears the LCD screen.

C Moves the cursor to the start.

D Displays 'Hi' on the LCD at the current cursor position.

lcd.print("Hi") writes the text 'Hi' on the LCD where the cursor is.

Explain how to connect and initialize a 16x2 LCD using the LiquidCrystal library in Arduino.

Think about wiring, code setup, and commands to show text.

Describe the steps to display a message on the second line of a 16x2 LCD using LiquidCrystal.

Remember rows start at 0, so second line is row 1.

Practice

1. What does the lcd.begin(16, 2) command do in the LiquidCrystal library?

easy

A. It clears the LCD screen.

B. It sets up the LCD screen size to 16 columns and 2 rows.

C. It moves the cursor to the first position.

D. It prints text on the LCD screen.

Solution

1. Step 1: Understand lcd.begin() function

   The lcd.begin() function initializes the LCD with the number of columns and rows.

2. Step 2: Apply to given parameters

   Using lcd.begin(16, 2) sets the screen size to 16 columns and 2 rows.

3. Final Answer:

   It sets up the LCD screen size to 16 columns and 2 rows. -> Option B

4. Quick Check:

   lcd.begin(16, 2) = sets screen size [OK]

Hint: Remember lcd.begin sets screen size first [OK]

Common Mistakes:

• Thinking lcd.begin clears the screen
• Confusing lcd.begin with lcd.print
• Assuming lcd.begin moves the cursor

2. Which of the following is the correct way to create a LiquidCrystal object for pins 12, 11, 5, 4, 3, 2?

easy

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

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

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

D. LiquidCrystal lcd(12, 11, 5, 4);

Solution

1. Step 1: Recall LiquidCrystal constructor syntax

   The constructor requires 6 pins: RS, Enable, D4, D5, D6, D7 in order.

2. Step 2: Match given pins to correct syntax

   LiquidCrystal lcd(12, 11, 5, 4, 3, 2); matches the correct order and number of pins.

3. Final Answer:

   LiquidCrystal lcd(12, 11, 5, 4, 3, 2); -> Option C

4. Quick Check:

   Constructor needs 6 pins in order [OK]

Hint: Count pins: constructor needs exactly 6 pins [OK]

Common Mistakes:

• Using wrong number of pins
• Wrong pin order
• Using assignment instead of constructor

3. What will be displayed on the LCD after running this code?

lcd.begin(16, 2);
lcd.setCursor(0, 1);
lcd.print("Hello");

medium

A. Hello on the second row

B. Nothing is displayed

C. Hello on both rows

D. Hello on the first row

Solution

1. Step 1: Understand lcd.setCursor(0, 1)

   Cursor moves to column 0, row 1 (second row, since rows start at 0).

2. Step 2: lcd.print("Hello") prints at cursor

   Text "Hello" appears on the second row starting at first column.

3. Final Answer:

   Hello on the second row -> Option A

4. Quick Check:

   setCursor(0,1) = second row [OK]

Hint: Rows start at 0, so row 1 is second row [OK]

Common Mistakes:

• Assuming row 1 is first row
• Forgetting cursor position before print
• Expecting text on both rows

4. Identify the error in this code snippet:

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
lcd.begin(16, 2);
lcd.setCursor(1, 2);
lcd.print("Hi");

medium

A. Cursor row 2 is invalid for 2-row LCD

B. lcd.begin() is missing

C. lcd.print() syntax is wrong

D. LiquidCrystal object not created properly

Solution

1. Step 1: Check lcd.setCursor parameters

   Rows are 0 and 1 for a 2-row LCD; row 2 is out of range.

2. Step 2: Confirm other code parts

   lcd.begin() is present, object created correctly, and print syntax is correct.

3. Final Answer:

   Cursor row 2 is invalid for 2-row LCD -> Option A

4. Quick Check:

   Row index must be 0 or 1 for 16x2 LCD [OK]

Hint: Rows start at 0; max row for 2-row LCD is 1 [OK]

Common Mistakes:

• Using row 2 instead of 0 or 1
• Forgetting lcd.begin() call
• Incorrect object creation syntax

5. You want to display the word "Ready" centered on the first row of a 16x2 LCD. Which code snippet correctly sets the cursor before printing?

hard

A. lcd.setCursor(8, 0); lcd.print("Ready");

B. lcd.setCursor(5, 0); lcd.print("Ready");

C. lcd.setCursor(7, 0); lcd.print("Ready");

D. lcd.setCursor(6, 0); lcd.print("Ready");

Solution

1. Step 1: Calculate starting position for centering

   LCD width is 16 columns; word length is 5 letters. (16 - 5) / 2 = 5.5, round to 6.

2. Step 2: Set cursor to column 6 on first row (row 0)

   Use lcd.setCursor(6, 0) to start printing "Ready" centered.

3. Final Answer:

   lcd.setCursor(6, 0); lcd.print("Ready"); -> Option D

4. Quick Check:

   (16-5)/2 = 5.5 ≈ 6 for centering [OK]

Hint: Center = (screen width - text length) / 2 rounded [OK]

Common Mistakes:

• Using wrong column for centering
• Confusing row numbers
• Not rounding the position