Enabling I2C on Raspberry Pi - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of the command to check I2C devices?

You have enabled I2C on your Raspberry Pi and connected a device. You run the command i2cdetect -y 1. What output do you expect if a device is connected at address 0x3C?

Raspberry Pi

sudo i2cdetect -y 1

A Error: command not found

B

     0 1 2 3 4 5 6 7 8 9 a b c d e f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- 3c -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

C No devices found

D Device detected at address 0x50

💡 Hint

Look for the hexadecimal address 3c in the output grid.

The i2cdetect -y 1 command scans the I2C bus 1 and shows detected devices by their addresses. If a device is at 0x3C, it appears in the grid at row 30 and column c.

🧠 Conceptual

intermediate

Which file enables I2C interface on Raspberry Pi?

To enable the I2C interface on Raspberry Pi, which configuration file do you edit?

A /boot/config.txt

B /etc/modules

C /etc/i2c.conf

D /boot/cmdline.txt

💡 Hint

This file contains boot-time settings for the Raspberry Pi.

The /boot/config.txt file is used to enable hardware interfaces like I2C by adding lines such as dtparam=i2c_arm=on.

🔧 Debug

advanced

Why does this Python I2C code raise an error?

You run this Python code to communicate with an I2C device but get an error:

import smbus
bus = smbus.SMBus(0)
bus.write_byte(0x3c, 0x00)

What is the most likely cause of the error?

A The smbus module is not installed

B The device address 0x3c is invalid

C write_byte requires three arguments

D Bus number 0 is incorrect; Raspberry Pi uses bus 1 for I2C

💡 Hint

Check which I2C bus number Raspberry Pi uses by default.

On Raspberry Pi models with newer hardware, I2C bus 1 is used. Using bus 0 causes an error because it does not exist or is not enabled.

📝 Syntax

advanced

Which command correctly loads the I2C kernel module?

You want to load the I2C kernel module manually. Which command is correct?

A sudo modprobe i2c-dev

B sudo loadmodule i2c-dev

C sudo insmod i2c-dev

D sudo modload i2c-dev

💡 Hint

The command to add kernel modules is a common Linux utility.

The correct command to load kernel modules is modprobe. i2c-dev is the module for I2C device interface.

🚀 Application

expert

How to verify I2C is enabled and working on Raspberry Pi?

You want to confirm that I2C is enabled and working on your Raspberry Pi. Which sequence of commands will correctly verify this?

A echo 'dtparam=i2c_arm=on' > /boot/config.txt → reboot → i2cdetect -y 0

B sudo modprobe i2c_bcm2708 → i2cdetect -y 0 → reboot

C sudo raspi-config (enable I2C) → reboot → lsmod | grep i2c_dev → i2cdetect -y 1

D sudo systemctl start i2c.service → i2cdetect -y 1 → ls /dev/i2c-1

💡 Hint

Use the Raspberry Pi configuration tool and check kernel modules and device scan.

The recommended way is to enable I2C via raspi-config, reboot, check if the i2c_dev module is loaded with lsmod, and then scan the bus with i2cdetect -y 1.