LCD display (16x2) with I2C backpack in Raspberry Pi - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output on the LCD after running this code?

Consider this Python code snippet for a Raspberry Pi connected to a 16x2 LCD with an I2C backpack. What text will appear on the first line of the LCD?

Raspberry Pi

import I2C_LCD_driver
lcd = I2C_LCD_driver.LCD()
lcd.lcd_display_string("Hello, World!", 1)
lcd.lcd_display_string("Line 2 Text", 2)

A Hello, World! on line 1 and Line 2 Text on line 2

B Line 2 Text on line 1 and Hello, World! on line 2

C Only Hello, World! on line 1, line 2 is blank

D Only Line 2 Text on line 2, line 1 is blank

💡 Hint

Look at the lcd_display_string method parameters: the string and the line number.

The lcd_display_string method takes the text and the line number (1 or 2). The first call writes "Hello, World!" on line 1, the second call writes "Line 2 Text" on line 2.

🧠 Conceptual

intermediate

Which I2C address is most commonly used for a 16x2 LCD with I2C backpack?

You want to communicate with a 16x2 LCD using I2C on Raspberry Pi. Which I2C address is typically used by these backpacks?

A 0x50

B 0x3F

C 0x68

D 0x27

💡 Hint

Common I2C backpack modules usually use either 0x27 or 0x3F.

Most 16x2 LCD I2C backpacks use the address 0x27 by default. Some use 0x3F, but 0x27 is more common.

🔧 Debug

advanced

Why does this code raise an error when initializing the LCD?

Look at this code snippet. It raises an AttributeError: module 'I2C_LCD_driver' has no attribute 'lcd'. What is the cause?

Raspberry Pi

import I2C_LCD_driver
lcd = I2C_LCD_driver.lcd()
lcd.lcd_display_string("Test", 1)

A The module I2C_LCD_driver is not installed

B The lcd_display_string method does not exist

C The class name is capitalized as 'LCD' not 'lcd' in the module

D The I2C address is incorrect

💡 Hint

Check the exact class name in the I2C_LCD_driver module.

The class in I2C_LCD_driver is named 'LCD' with uppercase letters, not 'lcd'. Python is case-sensitive, so calling 'lcd()' causes AttributeError.

📝 Syntax

advanced

Which option correctly initializes the LCD and clears the display?

You want to initialize the LCD and clear any previous text. Which code snippet is correct?

A

lcd = I2C_LCD_driver.LCD()
lcd.clear()

B

lcd = I2C_LCD_driver.LCD()
lcd.lcd_clear()

C

lcd = I2C_LCD_driver.lcd()
lcd.lcd_clear()

D

lcd = I2C_LCD_driver.LCD()
lcd.clear_display()

💡 Hint

Check the method name for clearing the display in the library.

The method to clear the LCD in I2C_LCD_driver is 'lcd_clear()'. The class name is 'LCD'.

🚀 Application

expert

How many characters can you display on a 16x2 LCD at once?

You have a 16x2 LCD connected via I2C. How many characters can you show on the screen at the same time?

A 32 characters

B 64 characters

C 2 characters

D 16 characters

💡 Hint

Think about the number of columns and rows multiplied.

A 16x2 LCD has 16 columns and 2 rows, so it can display 16 * 2 = 32 characters simultaneously.