Integrating a USB Barcode Scanner with Python on Raspberry Pi 4: A Step-by-Step Guide

Connecting a USB barcode scanner to a Raspberry Pi 4 and reading its input using Python is a straightforward process with significant practical applications. This setup is essential for creating automated systems in retail, inventory management, and smart shopping carts.

Steps to Get USB Barcode Scanner Input into Python on Raspberry Pi 4:

1. Connect the Scanner: Plug the USB barcode scanner into one of the Raspberry Pi’s USB ports.
2. Install Required Libraries: Use Python libraries like pyserial or pyzbar to read the scanner input.
3. Write the Python Script: Develop a Python script to capture and process the barcode data.

Importance and Applications:

• Retail and Inventory Management: Streamlines the process of tracking products and managing stock levels.
• Smart Shopping Carts: Enhances the shopping experience by automating item recognition and billing.
• Data Accuracy: Reduces human error in data entry, ensuring precise inventory records.

This integration not only simplifies data management but also opens up possibilities for innovative retail solutions.

Required Hardware and Software

Here are the necessary hardware and software components:

Hardware Components:

1. Raspberry Pi 4: The main computing device.
2. USB Barcode Scanner: A plug-and-play device to scan barcodes.
3. MicroSD Card: For the Raspberry Pi OS, at least 16GB recommended.
4. Power Supply: 5V, 2.5A or higher for the Raspberry Pi.
5. HDMI Cable and Display: For initial setup and debugging.
6. USB Keyboard and Mouse: For setup purposes.

Software Components:

1. Raspberry Pi OS: The operating system for the Raspberry Pi.
2. Python: The programming language to write the code.
3. PyUSB Library: To communicate with the USB barcode scanner.
4. zbarcam Tool: To test and read barcode data.

Setting Up the Raspberry Pi 4

Here are the steps to prepare your Raspberry Pi 4 for receiving input from a USB barcode scanner:

1. Connect the USB Barcode Scanner:

   • Plug the USB barcode scanner into one of the USB ports on the Raspberry Pi 4.

2. Boot the Raspberry Pi:

   • Power on your Raspberry Pi and wait for it to boot up.

3. Open Terminal:

   • Open the terminal on your Raspberry Pi.

4. Update and Upgrade:

   • Run the following commands to update and upgrade your system:

     sudo apt update
     sudo apt upgrade
     

5. Install Required Packages:

   • Install the necessary packages for handling USB devices:

     sudo apt install libusb-1.0-0-dev
     

6. Configure Serial Interface:

   • Open the Raspberry Pi configuration tool:

     sudo raspi-config
     

   • Navigate to Interfacing Options -> Serial.
   • Disable the login shell over serial and enable the serial port hardware.

7. Reboot:

   • Reboot your Raspberry Pi to apply the changes:

     sudo reboot
     

8. Test the Barcode Scanner:

   • Open a text editor or terminal.
   • Scan a barcode with the USB barcode scanner. The scanned data should appear in the text editor or terminal.

9. Optional: Install Python Libraries:

   • If you plan to use Python to handle the barcode data, install the necessary libraries:

     sudo apt install python3-pip
     pip3 install pyserial
     

10. Write a Python Script:

    • Create a Python script to read data from the barcode scanner:

      import serial
      
      ser = serial.Serial('/dev/ttyUSB0', 9600)
      while True:
          barcode = ser.readline().decode('utf-8').strip()
          print(barcode)
      

11. Run the Script:

    • Execute your Python script to start reading barcode data:

      python3 your_script.py
      

That’s it! Your Raspberry Pi 4 should now be ready to receive input from a USB barcode scanner.

Connecting the USB Barcode Scanner

1. Connect the USB Barcode Scanner:

   • Plug the USB barcode scanner into one of the USB ports on the Raspberry Pi 4.

2. Power Up the Raspberry Pi:

   • Connect the Raspberry Pi to a power source and boot it up.

3. Open Terminal:

   • Once the Raspberry Pi is booted, open the terminal.

4. Verify the Connection:

   • Type lsusb in the terminal and press Enter.
   • Look for an entry that corresponds to your barcode scanner in the list of connected USB devices.

5. Test the Scanner:

   • Open a text editor or the terminal.
   • Scan a barcode. The scanned data should appear in the text editor or terminal window.

That’s it! Your USB barcode scanner should now be connected and verified on the Raspberry Pi 4.

Writing the Python Code

Here’s a step-by-step guide to read and process input from a USB barcode scanner on a Raspberry Pi 4 using Python:

Step 1: Setup

1. Connect the USB Barcode Scanner to your Raspberry Pi.
2. Boot up your Raspberry Pi and open the terminal.

Step 2: Install Dependencies

1. Update your package list:

   sudo apt-get update
   

2. Install Python and pip:

   sudo apt-get install python3 python3-pip
   

3. Install the pyusb library:

   pip3 install pyusb
   

Step 3: Write the Python Script

1. Create a new Python file:

   nano barcode_reader.py
   

2. Add the following code to read from the USB barcode scanner:

   import usb.core
   import usb.util
   
   # Find the USB device
   dev = usb.core.find(idVendor=0xXXXX, idProduct=0xYYYY)
   
   # Check if the device is found
   if dev is None:
       raise ValueError('Device not found')
   
   # Set the active configuration
   dev.set_configuration()
   
   # Get an endpoint instance
   cfg = dev.get_active_configuration()
   intf = cfg[(0, 0)]
   
   ep = usb.util.find_descriptor(
       intf,
       # Match the first IN endpoint
       custom_match=lambda e: usb.util.endpoint_direction(e.bEndpointAddress) == usb.util.ENDPOINT_IN
   )
   
   assert ep is not None
   
   # Read data
   while True:
       try:
           data = dev.read(ep.bEndpointAddress, ep.wMaxPacketSize)
           barcode = ''.join([chr(x) for x in data])
           print('Barcode: ', barcode)
       except usb.core.USBError as e:
           if e.args == ('Operation timed out',):
               continue
   

Step 4: Run the Script

1. Save and exit the editor (Ctrl+X, then Y, then Enter).
2. Run the script:

   python3 barcode_reader.py
   

Notes

• Replace 0xXXXX and 0xYYYY with the vendor ID and product ID of your barcode scanner. You can find these using the lsusb command.
• Ensure your barcode scanner is in HID mode (most are by default).

This script will continuously read and print barcode data from the scanner.

Testing and Troubleshooting

Testing USB Barcode Scanner Input in Python on Raspberry Pi 4

1. Connect the Scanner:

   • Plug the USB barcode scanner into one of the Raspberry Pi’s USB ports.

2. Install Required Packages:

   • Open the terminal and install necessary packages:

     sudo apt-get update
     sudo apt-get install python3-pip
     pip3 install pyserial
     

3. Write a Python Script:

   • Create a Python script to read input from the scanner:

     import serial
     
     ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=1)
     ser.flush()
     
     while True:
         if ser.in_waiting > 0:
             barcode = ser.readline().decode('utf-8').rstrip()
             print("Scanned Barcode: ", barcode)
     

4. Run the Script:

   • Execute the script:

     python3 barcode_reader.py
     

5. Test the Scanner:

   • Scan a barcode and check if the output appears in the terminal.

Troubleshooting Tips

1. No Output:

   • Ensure the scanner is properly connected.
   • Verify the correct serial port (/dev/ttyUSB0). Use dmesg | grep tty to find the correct port.

2. Incorrect Data:

   • Check the baud rate and other serial settings in the script. They should match the scanner’s settings.

3. Permission Issues:

   • If you encounter permission errors, run the script with sudo or add your user to the dialout group:

     sudo usermod -aG dialout $USER
     

4. Scanner Not Recognized:

   • Ensure the scanner is in HID mode. Some scanners have different modes (e.g., HID, Serial). Refer to the scanner’s manual to switch modes if necessary.

These steps should help you set up and troubleshoot your USB barcode scanner on a Raspberry Pi 4.

To Get a USB Barcode Scanner Input into Python on a Raspberry Pi 4

You’ll need to connect the scanner, install required packages, write a Python script, and run it. Here’s a step-by-step guide:

1. Connect the scanner to one of the Raspberry Pi’s USB ports.
2. Install necessary packages by running <pre>sudo apt-get update</pre>, <pre>sudo apt-get install python3-pip</pre>, and <pre>pip3 install pyserial</pre>.
3. Write a Python script using the serial library to read input from the scanner. You can use the following code as a starting point:

   import serial
   ser = serial.Serial('/dev/ttyUSB0', 9600, timeout=1)
   ser.flush()
   
   while True:
       if ser.in_waiting > 0:
           barcode = ser.readline().decode('utf-8').rstrip()
           print("Scanned Barcode:", barcode)

4. Run the script by executing <pre>python3 barcode_reader.py</pre>.
5. Test the scanner by scanning a barcode and checking if the output appears in the terminal.