Custom characters on LCD in Arduino - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a custom character on the LCD.

Arduino

byte smiley[8] = {0x00, 0x0A, 0x00, 0x00, 0x11, 0x0E, 0x00, [1];

Drag options to blanks, or click blank then click option'

A0x00

B0x1F

C0x10

D0x05

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-zero value for the last byte can distort the character shape.

The last byte in the custom character array is 0x00 to complete the 8-byte pattern.

2fill in blank

medium

Complete the code to load the custom character into the LCD memory.

Arduino

lcd.createChar([1], smiley);

Drag options to blanks, or click blank then click option'

A1

B0

C8

D16

Attempts:

3 left

💡 Hint

Common Mistakes

Using an index outside 0-7 causes errors or overwrites memory.

Custom characters are stored in locations 0 to 7 in LCD memory; 0 is the first slot.

3fill in blank

hard

Fix the error in the code to display the custom character on the LCD.

Arduino

lcd.setCursor(0, 0);
lcd.write([1]);

Drag options to blanks, or click blank then click option'

A0

B1

C'0'

Dsmiley

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the array name instead of the index.

Using character literals like '0' instead of numeric index.

lcd.write() expects the index of the custom character (0-7), not the array or character literal.

4fill in blank

hard

Fill both blanks to define and display a heart custom character on the LCD.

Arduino

byte heart[8] = [1];
lcd.createChar(1, [2]);

Drag options to blanks, or click blank then click option'

A{0x00, 0x0A, 0x1F, 0x1F, 0x1F, 0x0E, 0x04, 0x00}

Bsmiley

Cheart

D{0x00, 0x04, 0x0E, 0x1F, 0x1F, 0x0A, 0x00, 0x00}

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the wrong array or variable name to createChar.

Using incorrect byte patterns for the heart shape.

The heart array must be defined with the correct byte pattern and passed to createChar.

5fill in blank

hard

Fill all three blanks to create, store, and display a smiley face custom character at position (0,1).

Arduino

byte smiley[8] = [1];
lcd.createChar([2], smiley);
lcd.setCursor(0, [3]);
lcd.write([2]);

Drag options to blanks, or click blank then click option'

A{0x00, 0x0A, 0x00, 0x00, 0x11, 0x0E, 0x00, 0x00}

B0

C1

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up the index for createChar and write.

Incorrect cursor position for displaying the character.

Define the smiley array, store it at index 0, then set cursor to column 0, row 1, and write the character at index 0.

Practice

1. What is the main purpose of using createChar() in Arduino LCD programming?

easy

A. To clear the LCD screen

B. To define a custom character pattern for the LCD

C. To set the cursor position on the LCD

D. To print a string on the LCD

Solution

1. Step 1: Understand the function of createChar()

   This function is used to define a new character pattern by specifying pixel rows for the LCD.

2. Step 2: Compare with other LCD functions

   Functions like clearing the screen, setting cursor, or printing strings are different and not related to defining custom characters.

3. Final Answer:

   To define a custom character pattern for the LCD -> Option B

4. Quick Check:

   createChar() defines custom characters [OK]

Hint: Remember: createChar defines, write displays [OK]

Common Mistakes:

• Confusing createChar with print or clear functions
• Thinking createChar moves the cursor
• Assuming createChar prints text directly

2. Which of the following is the correct way to declare a custom character array for createChar()?

easy

A. byte smiley[8] = {0, 10, 0, 0, 17, 14, 0, 0};

B. int smiley[8] = {0, 10, 0, 0, 17, 14, 0, 0};

C. char smiley[5] = {0, 10, 0, 0, 17};

D. byte smiley[7] = {0, 10, 0, 0, 17, 14, 0};

Solution

1. Step 1: Check data type and array size

   Custom characters require 8 bytes (one for each row) and use the byte type for pixel data.

2. Step 2: Validate array length and type

   byte smiley[8] = {0, 10, 0, 0, 17, 14, 0, 0}; uses byte type and 8 elements, matching the LCD custom character format.

3. Final Answer:

   byte smiley[8] = {0, 10, 0, 0, 17, 14, 0, 0}; -> Option A

4. Quick Check:

   8 bytes array with byte type = correct declaration [OK]

Hint: Custom chars need 8 bytes, not int or fewer elements [OK]

Common Mistakes:

• Using int instead of byte
• Using fewer than 8 elements
• Using char type which is signed and may cause issues

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

byte heart[8] = {0,10,31,31,31,14,4,0};
lcd.createChar(0, heart);
lcd.setCursor(0,0);
lcd.write(byte(0));

medium

A. The LCD prints the number 0

B. The LCD shows a blank space

C. The code causes a compile error

D. A heart-shaped custom character appears at the top-left corner

Solution

1. Step 1: Understand createChar and write usage

   The code defines a heart pattern, stores it at position 0, then writes character 0 at cursor (0,0).

2. Step 2: Predict LCD output

   Writing byte(0) displays the custom character stored at position 0, which is the heart shape.

3. Final Answer:

   A heart-shaped custom character appears at the top-left corner -> Option D

4. Quick Check:

   createChar + write(byte(0)) = custom char display [OK]

Hint: write(byte(0)) prints custom char stored at 0 [OK]

Common Mistakes:

• Expecting numeric 0 to print
• Forgetting to use byte() cast in write()
• Assuming createChar prints automatically

4. Identify the error in this code snippet for displaying a custom character:

byte star[8] = {4,14,21,4,4,0,4,0};
lcd.createChar(1, star);
lcd.setCursor(0,0);
lcd.write(1);

medium

A. Missing byte cast in lcd.write(1)

B. Array size is incorrect

C. createChar index must be 0, not 1

D. setCursor parameters are invalid

Solution

1. Step 1: Check usage of lcd.write()

   When writing a custom character, the index must be cast to byte, so lcd.write(byte(1)) is correct.

2. Step 2: Verify other parts

   Array size is 8, createChar index 1 is valid (0-7), setCursor(0,0) is valid.

3. Final Answer:

   Missing byte cast in lcd.write(1) -> Option A

4. Quick Check:

   Use byte() cast in write() for custom chars [OK]

Hint: Always cast index with byte() in lcd.write() [OK]

Common Mistakes:

• Not casting index to byte in lcd.write()
• Thinking createChar index must be zero
• Assuming setCursor(0,0) is invalid

5. You want to display two different custom characters side by side on the LCD. Which sequence correctly creates and displays them?

hard

A. Define two byte arrays, use createChar(1, char1) and createChar(2, char2), then write(1) and write(2).

B. Define one byte array with 16 elements, use createChar(0, array), then write(0) twice.

C. Define two byte arrays, use createChar(0, char1) and createChar(1, char2), then write(byte(0)) and write(byte(1)) in order.

D. Use createChar(0, char1) twice, then write(0) and write(1).

Solution

1. Step 1: Understand createChar indexing

   Custom characters are stored in slots 0 to 7. To display two different chars, use two slots, e.g., 0 and 1.

2. Step 2: Display characters correctly

   Use write(byte(0)) and write(byte(1)) to print the two custom characters side by side.

3. Final Answer:

   Define two byte arrays, use createChar(0, char1) and createChar(1, char2), then write(byte(0)) and write(byte(1)) in order. -> Option C

4. Quick Check:

   Two createChar slots + write(byte(index)) = display two chars [OK]

Hint: Use slots 0 and 1, write with byte() cast [OK]

Common Mistakes:

• Trying to store both chars in one array
• Using invalid createChar indexes like 2 or higher without checking
• Not casting index to byte in write()