Setting up a USB thermal printer with a Raspberry Pi 3B+

It involves a few key steps. Here’s a complete guide to get it working:

1. Gather Required Materials

• Raspberry Pi 3B+ (with Raspbian OS installed)
• USB thermal printer
• USB cable to connect the printer
• Printer paper
• Power supply for the Raspberry Pi and printer

2. Connect the Printer

1. Connect the thermal printer to the Raspberry Pi via the USB port.
2. Ensure the printer is powered on and loaded with paper.

3. Install Required Packages

Open the terminal on your Raspberry Pi and install the necessary software:

Download the driver software for the printer. 

Use install.sh file to install it.

$chmod +x install.sh      // make the install.sh file executable

$sudo ./install.sh       // run the install.sh 

$sudo apt install cups libcups2-dev printer-driver-escpr

• CUPS (Common Unix Printing System) is a printing system that allows the Raspberry Pi to communicate with printers.

• printer-driver-escpr includes drivers for many thermal printers.

4. Add User to the lpadmin Group

This gives your user permissions to manage printers:

$sudo usermod -a -G lpadmin pi

Log out and log back in to apply the changes.

5. Configure CUPS

1. Open the CUPS web interface:

   $sudo cupsctl --remote-any
   $sudo systemctl restart cups
   Go to the "Administration" tab in the CUPS interface.
   Click on "Add Printer."
   Select your thermal printer from the list of detected printers.
   Choose the appropriate driver for your printer (e.g., ESC/POS or a specific model).
   

   Access the web interface by navigating to http://localhost:631 in your browser. You can Replace localhost with your Raspberry Pi's IP address.

2. Add your printer:

3. Configure printer settings as needed (e.g., paper size).

6. Test the Printer

Send a test print from the CUPS interface or the terminal:

echo "Test print from Raspberry Pi" | lp

7. Install Python Library for Thermal Printers (Optional)

If you plan to use Python for controlling the printer, install libraries like python-escpos:

Use virtual environment for few packages if pip install ask for --break-system-packages. Create a virtual environment in your project folder and then install the required packages.

- Create a virtual environment : Go the folder using CD command

• $cd /Project Folder/
• $python3 -m venv venvName               #create virtual environment
• $source venvName/bin/activate           #activate the environment

• Install following packages in the virtual environment:
• $pip install python-escpos
• $pip3 install pyusb

• $sudo apt install libusb-1.0-0-dev libudev-dev -y
• $sudo apt install usbutils

• $sudo nano /etc/udev/rules.d/99-escpos.rules
• add the below line in the file
• SUBSYSTEM=="usb", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="5743", MODE="0666", GROUP="lp"

Example Python script for printing:

from escpos.printer import Usb

# Replace with your printer's VendorID and ProductID
printer = Usb(0x0483, 0x5743, 0)
printer.text("Hello, Thermal Printer!\n")
printer.cut()
printer.close()

Find the Vendor ID and Product ID of your printer using following command:

$lsusb

8. Troubleshooting

• Printer not detected: Check the USB connection and power.
• Driver issues: Ensure you’ve selected the correct driver in CUPS.
• Permission errors: Ensure the pi user is in the lpadmin group.

Once everything is configured, your thermal printer should be ready for use with your Raspberry Pi 3B+.