How to Make a Raspberry Pi Car Scanner (2018 Guide & Beyond)

Are you fascinated by what’s under the hood of your car and love tinkering with technology? Building a car scanner using a Raspberry Pi is a fantastic project that combines automotive diagnostics with DIY electronics. This guide, inspired by the original Raspberry Pi car scanner concept from 2018, will walk you through the process, ensuring you have a solid foundation to create your own in-car diagnostic tool. While technology has advanced, the core principles remain relevant, and we’ll update you with insights for today’s context.

Before diving in, let’s consider the skills and tools you’ll need for this exciting project.

Skills You’ll Need:

• Automotive Wiring Basics: Understanding car electrical systems is helpful, although this project focuses on low-voltage connections. You’ll be dealing with power and possibly tapping into your car’s electrical system safely.
• Basic Circuit Knowledge: A grasp of simple circuits will help you understand how the components interact, especially when powering your Raspberry Pi from your car.
• Python Programming: Python is the primary language for interacting with OBD-II data on the Raspberry Pi. Basic scripting knowledge is necessary to read and display car data.
• Soldering (Potentially): Depending on your power solution and screen integration, soldering might be required to create robust and reliable connections.
• Linux Command Line: Raspberry Pi OS is Linux-based. Navigating the command line is essential for installing software, configuring your Pi, and running scripts.

Tools You’ll Need:

• Wire Strippers: For preparing wires for connections.
• Soldering Iron (and Solder): If you choose to solder connections, especially for power.
• Computer or Laptop: To program your Raspberry Pi and remotely access it.
• Computer Monitor or TV: Initially, you’ll need a display to set up your Raspberry Pi. This can be your regular computer monitor.

Parts You’ll Need:

• Raspberry Pi Zero W or Raspberry Pi 3/4: These models are recommended because of their built-in Wi-Fi and Bluetooth capabilities, crucial for connecting to an OBD-II reader and remote access. While the original article mentioned 2018 models, newer Raspberry Pi versions are even more powerful and readily available.

• MicroSD Card: To install the Raspberry Pi operating system. At least 16GB is recommended for sufficient space.

• OBDII Bluetooth Adapter: This device plugs into your car’s OBD-II port and wirelessly transmits vehicle data. Popular options are available on Amazon. Ensure it’s compatible with your car model and the Raspberry Pi.

• Power Supply for Raspberry Pi: Raspberry Pis are powered by MicroUSB (or USB-C for newer models). Car USB ports might not provide consistent power. Consider these options:

  • Cigarette Lighter USB Adapter: A simple way to power the Pi from your car’s 12V socket.
  • Step-Down Voltage Converter (UBEC): For a more permanent and efficient solution, a UBEC (like the Hobbywing 5V UBEC) reduces your car’s 12V to the 5V needed by the Pi. This provides a stable power source.

• Screen (Optional but Recommended): While not essential for initial setup, a screen makes your car scanner truly portable. Options include:

  • Small HDMI Screen: Raspberry Pis have HDMI output. Compact HDMI screens are available, like those from Adafruit.
  • Touchscreen Display: For a more interactive experience, consider a Raspberry Pi compatible touchscreen.

• Power Switch (Highly Recommended): A switch like the Mausberry Circuits Car Supply Switch offers a clean way to power your Pi from your car and ensures a safe shutdown when you turn off the ignition, preventing SD card corruption.

• Fuse Taps (Add-a-circuit): To safely tap into your car’s fuse box for power without cutting or splicing existing wires.

Rough Steps to Build Your Raspberry Pi Car Scanner:

1. Set up your Raspberry Pi: Install the operating system and enable remote access.
2. Install and Test the Bluetooth OBDII Reader: Ensure it can communicate with your car.
3. Connect Raspberry Pi to the OBD Reader via Bluetooth: Establish the wireless link for data transfer.
4. Wire the Raspberry Pi to Your Car’s Power: Integrate the power supply into your vehicle’s electrical system.
5. Dive into Code: Write Python scripts to read and display data from your car.

Step-by-Step Guide:

Step 1: Setting Up Your Raspberry Pi

• Part 1: Install Raspberry Pi OS:

  • Download the Raspberry Pi Imager software onto your computer from the official Raspberry Pi website.
  • Insert your microSD card into your computer.
  • Use the Raspberry Pi Imager to install the Raspberry Pi OS (Raspberry Pi OS Lite is sufficient for this project as it’s more lightweight, but the Desktop version is fine too if you prefer a graphical interface initially).
  • Follow the official Raspberry Pi guide: https://www.raspberrypi.org/learning/software-guide/ for detailed instructions.

• Part 2: Enable SSH and VNC:

  • SSH (Secure Shell): Allows you to remotely access your Pi via the command line. Enable SSH by creating an empty file named ssh (no extension) on the boot partition of your microSD card after flashing the OS.
  • VNC (Virtual Network Computing): Provides a graphical desktop remote access. Enable VNC through the Raspberry Pi Configuration menu (if using Desktop version) or via command line using sudo raspi-config and navigating to Interfacing Options.
  • Refer to the official Raspberry Pi documentation for remote access: https://www.raspberrypi.org/documentation/remote-access/vnc/README.md

• Part 3: Install Necessary Packages:

  • Open a terminal window on your Raspberry Pi (either directly if using a monitor or remotely via SSH).
  • Update Package Lists: Ensure your system is up to date by running:

    sudo apt-get update
    sudo apt-get upgrade

  • Install PIP (Python Package Installer): PIP is used to install Python libraries. It’s often pre-installed, but to ensure:

    sudo apt-get -y install python3-pip

  • Install the obd Library: This is the core Python library for OBD-II interaction:

    sudo pip3 install obd

  • Install pyserial: For Bluetooth serial communication:

    sudo apt-get install python3-serial

Step 2: Install and Test the OBD Bluetooth Reader

• Locate your car’s OBD-II port. It’s typically under the dashboard on the driver’s side.
• Plug in your Bluetooth OBD-II reader.
• Turn your car’s ignition to the “ON” position (engine doesn’t need to be running for initial testing, but some readers might require it).
• Test the OBD-II reader with your smartphone using a compatible OBD-II app (like Torque Pro on Android or OBD Fusion on iOS). This verifies the reader is functioning and communicating with your car.

Step 3: Connect the Raspberry Pi and OBD Reader via Bluetooth

• This step can be tricky due to Bluetooth pairing complexities. Ensure Bluetooth is enabled on your Raspberry Pi.
• Use the command line on your Raspberry Pi to scan for Bluetooth devices:

  sudo bluetoothctl
  scan on

• Identify your OBD-II reader from the list of devices (it will likely have a name like “OBDII” or similar). Note down its Bluetooth address (XX:XX:XX:XX:XX:XX).
• Pair with the OBD-II reader:

  pair XX:XX:XX:XX:XX:XX

• Trust the device:

  trust XX:XX:XX:XX:XX:XX

• Connect to the device:

  connect XX:XX:XX:XX:XX:XX

• Assign a Serial Port: To make the Bluetooth connection usable by the obd library, you need to assign it a serial port using rfcomm:

  sudo rfcomm bind 0 XX:XX:XX:XX:XX:XX

  Replace XX:XX:XX:XX:XX:XX with your OBD-II reader’s Bluetooth address. 0 assigns it to /dev/rfcomm0.

• Persistence (Important): This rfcomm connection is lost on reboot. You’ll need to automate this command to run on startup. Methods include using rc.local or creating a systemd service (more advanced). For testing, you can manually run the sudo rfcomm connect hci0 XX:XX:XX:XX:XX:XX command each time you reboot. hci0 refers to your Raspberry Pi’s Bluetooth interface.

Step 4: Wiring the Pi to Your Car

• Powering the Raspberry Pi:
  • Choose a Power Method: UBEC for a clean, permanent install, or cigarette lighter adapter for simplicity.
  • Fuse Tap Installation (Recommended for UBEC): Use fuse taps to draw power from a fuse in your car’s fuse box that is only active when the ignition is on (switched power). This prevents battery drain when the car is off and allows the Mausberry switch (if used) to manage shutdown.
  • Grounding: Ensure the ground wire from your power supply is securely connected to a ground point in your car’s chassis.
• Safe Shutdown: Implementing a safe shutdown is crucial to prevent SD card corruption. The Mausberry switch simplifies this by detecting ignition off and initiating a controlled shutdown of the Raspberry Pi. If not using a Mausberry switch, you’ll need to write a script that monitors the ignition and triggers a sudo shutdown now command when power is lost.
• Screen Wiring (If using a screen): Follow the instructions specific to your chosen screen for connecting power and data cables to the Raspberry Pi.

Step 5: Code Land – Reading OBD-II Data with Python

• Basic Connection Test: Use the following Python code to test the connection and list supported commands:

  import obd
  
  connection = obd.OBD() # Auto-connects to OBD-II port (via rfcomm0)
  
  print("Connection Status: " + connection.status())
  print("Protocol Name: " + connection.protocol_name())
  
  commands = connection.supported_commands
  print("Supported Commands:")
  for command in commands:
      print(command.name)
  
  connection.close()

  Save this code as a Python file (e.g., obd_test.py) and run it from the terminal: python3 obd_test.py.

• Explore OBD-II Commands: The obd library documentation (http://python-obd.readthedocs.io/en/latest/) is your best resource for understanding available commands and how to retrieve specific data like RPM, speed, coolant temperature, etc.

• Develop Your Application: Start writing Python code to:

  • Connect to the OBD-II port.
  • Retrieve the data you want to monitor.
  • Format and display the data on your chosen screen or log it to a file.
  • Consider using GUI libraries like Tkinter or Kivy for a more user-friendly interface if displaying on a screen.

Conclusion:

Building a Raspberry Pi car scanner is a rewarding project that blends electronics, programming, and automotive knowledge. While this guide provides a strong starting point inspired by the 2018 concept, remember that continuous learning and adaptation are key. Dive deeper into the Python obd library, explore Raspberry Pi community forums for troubleshooting tips, and most importantly, have fun experimenting! You’re now on your way to creating a custom car diagnostic tool tailored to your needs.