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Enabling SPI and I2C on Ubuntu 20.04 Raspberry Pi: A Comprehensive Guide

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In this guide, we will walk you through the process of enabling SPI (Serial Peripheral Interface) and I2C (Inter-Integrated Circuit) on Ubuntu 20.04 running on a Raspberry Pi. These interfaces are crucial for communication with many peripheral devices.

Quick Answer

Enabling SPI and I2C on Ubuntu 20.04 Raspberry Pi involves checking and adding a line in the syscfg.txt file for SPI, and installing and configuring raspi-config, dependencies, and packages for I2C. The process requires some command line work and may involve fixing permission errors.

Prerequisites

Before we start, ensure that you have:

  • A Raspberry Pi with Ubuntu 20.04 installed.
  • Access to a terminal window/command line.
  • Basic knowledge of Linux commands.

Enabling SPI

The SPI interface might be enabled by default on Ubuntu 20.04. To check this, you can examine the /boot/firmware/syscfg.txt file.

cat /boot/firmware/syscfg.txt

Look for the following line:

dtparam=spi=on

If this line is present, SPI is already enabled.

If not, you can manually add this line to the /boot/firmware/usercfg.txt file:

echo "dtparam=spi=on" | sudo tee -a /boot/firmware/usercfg.txt

This command uses echo to print the required parameter, and tee command with -a (append) flag to add it to the usercfg.txt file.

After adding the line, reboot your Raspberry Pi:

sudo reboot

Enabling I2C

The process of enabling I2C is a bit more involved.

Step 1: Install raspi-config

raspi-config is a configuration tool in Raspbian. To install it on Ubuntu, download it from the Raspberry Pi repository:

wget https://archive.raspberrypi.org/debian/pool/main/r/raspi-config/raspi-config_20200601_all.deb

Then, install it using dpkg:

sudo dpkg -i raspi-config_20200601_all.deb

Step 2: Install Dependencies

You might encounter dependency issues after the installation. Install the necessary dependencies using apt-get:

sudo apt-get install -f

Step 3: Enable I2C

Run raspi-config:

sudo raspi-config

Navigate to ‘Interfacing Options’ -> ‘I2C’ and enable it.

Step 4: Install I2C Packages

Install the i2c-tools, libi2c-dev, and python3-smbus packages:

sudo apt-get install i2c-tools libi2c-dev python3-smbus

Step 5: Check I2C Bus

Probe the I2C bus:

i2cdetect -y 1

If you get an address matrix, I2C is working. If you encounter a permission error, proceed to the next step.

Step 6: Fix Permission Error

Create an I2C usergroup and apply it to the bus:

sudo groupadd i2c
sudo chown :i2c /dev/i2c-1
sudo chmod g+rw /dev/i2c-1

Add your user to this group:

sudo usermod -a -G i2c $USER

Step 7: Reboot

Log out and log in again, or reboot the Raspberry Pi:

sudo reboot

Step 8: Retry I2C Bus Check

Retry the i2cdetect command to check if the permission issue is resolved.

i2cdetect -y 1

If you see an address matrix, I2C is now working correctly.

Conclusion

In this guide, we have shown you how to enable SPI and I2C on Ubuntu 20.04 for Raspberry Pi. Although there is no official documentation for this process, the steps outlined above should help you enable these interfaces successfully. Remember, the instructions were specifically tested on a Raspberry Pi 4 with Ubuntu 20.04 64-bit, and if you are using a different version or model, you may need to tailor the dependencies and steps accordingly.

What is SPI?

SPI stands for Serial Peripheral Interface. It is a synchronous serial communication interface that allows for communication between microcontrollers and peripheral devices.

What is I2C?

I2C stands for Inter-Integrated Circuit. It is a serial communication protocol that allows multiple devices to be connected to the same bus, enabling communication between them.

How do I check if SPI is enabled on my Raspberry Pi?

You can check if SPI is enabled by examining the /boot/firmware/syscfg.txt file. Look for the line dtparam=spi=on. If this line is present, SPI is already enabled.

How do I enable SPI on Ubuntu 20.04 Raspberry Pi?

If SPI is not enabled, you can manually add the line dtparam=spi=on to the /boot/firmware/usercfg.txt file. After adding the line, reboot your Raspberry Pi.

How do I check if I2C is enabled on my Raspberry Pi?

You can check if I2C is enabled by running the i2cdetect -y 1 command. If you see an address matrix, I2C is working.

How do I enable I2C on Ubuntu 20.04 Raspberry Pi?

To enable I2C, you need to install raspi-config, install necessary dependencies, run raspi-config to enable I2C, install I2C packages, fix any permission errors, and reboot your Raspberry Pi.

What should I do if I encounter a permission error when checking the I2C bus?

If you encounter a permission error, you can fix it by creating an I2C usergroup and applying it to the bus using the chown and chmod commands. Additionally, you need to add your user to the I2C group using the usermod command.

Are these instructions specific to Raspberry Pi 4 with Ubuntu 20.04 64-bit?

Yes, these instructions were specifically tested on a Raspberry Pi 4 with Ubuntu 20.04 64-bit. If you are using a different version or model, you may need to tailor the dependencies and steps accordingly.

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