Thermal Printer Interfacing with Raspberry Pi

Project Overview

This project demonstrates how to interface a Thermal Printer with Raspberry Pi using hardware serial communication (UART) to print receipts containing logos, QR codes, barcodes, text, and graphical characters. The project uses the python-escpos library to control the thermal printer and send ESC/POS commands for various printing operations.

Project Tutorial: Circuit Digest - Thermal Printer Interfacing with Raspberry Pi

Features

Print formatted text with customizable fonts and sizes
Generate and print QR codes
Generate and print barcodes (CODE39, CODE128, UPC, etc.)
Print images and logos
Create professional receipts with alignment and styling
Hardware serial communication via GPIO pins
Support for ESC/POS commands
Low power consumption and eco-friendly operation

Components Required

Component Name	Quantity	Description
Thermal Printer (MAXIM PNP-500)	1	ESC/POS compatible thermal printer
Raspberry Pi 3 or Raspberry Pi Zero	1	Main controller board
Jumper Wires (Male to Female)	As required	For connections
9V 1A Power Adapter	1	Power supply for thermal printer
Thermal Paper Roll (57mm)	As required	Printing paper

Note: The printer requires at least 6V to operate. Always check your printer's user manual for specific power requirements.

About Thermal Printers

A thermal printer uses a heating head on thermal paper to produce images without requiring ink cartridges or ribbons. This makes them:

Cost-effective: No consumables like ink or toner
Eco-friendly: Minimal waste generation
Quiet operation: Noise-free printing
Fast: Quick monochromatic printing
Durable: Print head life up to 50 km
Compact: Small form factor ideal for embedded applications

Thermal printers are widely used in:

Point of Sale (POS) systems
Ticket counters
Grocery stores
Healthcare facilities
Entertainment venues
Corporate industries

Technical Specifications

MAXIM PNP-500 Thermal Printer

Specification	Details
Print Method	Thermal Direct Line Printing
Paper Width	57 mm
Print Width	48 mm
Resolution	8 dots/mm (384 dots/line)
Print Speed	50 mm/sec (Max: 80 mm/sec)
Character Size	9×17 dots, 12×24 dots
Chinese Character Size	12×24 dots, 24×24 dots
Interface	Serial (RS232C, TTL) / USB
Input Power	DC 5-9V / 12V
Operating Temperature	0°C ~ 55°C
Operating Humidity	10% ~ 80%
Dimensions	76.8 × 77.4 × 47.6 mm (W×D×H)
Paper Roll Specification	Width: 58mm, Max diameter: 40mm

Circuit Diagram

Pin Connections

Thermal Printer	Raspberry Pi GPIO
RXD	GPIO 14 (TXD)
TXD	GPIO 15 (RXD)
GND	GND
VCC	9V Power Supply
TDR	GND

Important Notes:

Cross-connect RX and TX pins (Printer RX → Pi TX, Printer TX → Pi RX)
Connect TDR pin to GND if printer doesn't print
Use dedicated 9V power supply for the printer
Serial port: /dev/serial0 (ttyAMA0)
Default baud rate: 9600

Prerequisites

Hardware Setup

Raspberry Pi 3 or Raspberry Pi Zero
Raspberry Pi OS (Raspbian) installed
Internet connection for package installation
SSH or direct terminal access

Software Requirements

Python 3.x
pip package manager
python-escpos library

Installation

Step 1: Enable Hardware Serial Port

Open the Raspberry Pi configuration tool:

sudo raspi-config

Navigate to: Interfacing Options → Serial Port

Serial Login Shell: No (Disable)
Hardware Serial Port: Yes (Enable)

Reboot your Raspberry Pi:

sudo reboot

Step 2: Verify Serial Port

Check if serial port is enabled:

ls -l /dev

You should see /dev/serial0 linked to ttyAMA0.

Step 3: Install python-escpos Library

Install the library using pip:

sudo pip install python-escpos

Or for Python 3:

sudo pip3 install python-escpos

Step 4: Connect Hardware

Connect the thermal printer to Raspberry Pi GPIO pins as per the circuit diagram
Connect the 9V power adapter to the thermal printer
Load thermal paper into the printer

Usage

Basic Initialization

from escpos.printer import Serial

# Initialize serial connection
p = Serial(
    devfile='/dev/serial0',
    baudrate=9600,
    bytesize=8,
    parity='N',
    stopbits=1,
    timeout=1.00,
    dsrdtr=True
)

Print Simple Text

p.text("Hello World\n")

Code Examples

1. Set Text Properties

p.set(
    underline=1,
    align="left",
    font="a",
    width=2,
    height=2,
    density=3,
    invert=0,
    smooth=False,
    flip=False,
)
p.textln("Hello World")

2. Print Barcode

# CODE39 barcode
p.barcode('123456', 'CODE39')

# CODE128 barcode
p.barcode('CIRCUITDIGEST', 'CODE128')

3. Print QR Code

p.qr("Circuit Digest", native=True, size=12)

4. Print Image

# Image width should not exceed 360 pixels
p.image("/home/pi/logo.png", impl="bitImageColumn")

5. Text Alignment

# Left align
p.set(align="left")
p.text("Left Aligned Text\n")

# Center align
p.set(align="center")
p.text("Center Aligned Text\n")

# Right align
p.set(align="right")
p.text("Right Aligned Text\n")

Sample Receipt Output

Complete Receipt Printing Code

from escpos.printer import Serial
from datetime import datetime

# Get current date and time
now = datetime.now()
dt_string = now.strftime("%b/%d/%Y %H:%M:%S")

# Initialize printer
p = Serial(
    devfile='/dev/serial0',
    baudrate=9600,
    bytesize=8,
    parity='N',
    stopbits=1,
    timeout=1.00,
    dsrdtr=True
)

# Print logo
p.set(align="center", width=2, height=2)
p.image("/home/pi/logo.png", impl="bitImageColumn")

# Print header
p.set(align="left")
p.textln("CIRCUIT DIGEST\n")
p.text("AIRPORT ROAD\n")
p.text("LOCATION : JAIPUR\n")
p.text("TEL : 0141222585\n")
p.text("GSTIN : \n")
p.text("Bill No. : \n\n")

# Print date and time
p.set(width=2, height=2)
p.text("DATE : ")
p.text(dt_string)
p.textln("\n")

p.textln("CASHIER : ")
p.textln(" ===========================")
p.textln(" ITEM       QTY  PRICE   GB")
p.textln(" --------------------------")
p.textln("IR SENSOR    2     30    60")
p.textln("ULTRASONIC   2     80   160")
p.textln("RASPBERRY    1   3300  3300")
p.textln("ADOPTOR      2    120   240")
p.textln(" --------------------------")
p.textln("           SUBTOTAL:   3760")
p.textln("           DISCOUNT:    0.8")
p.textln("         VAT @ 18%:  676.8")
p.textln(" ===========================")
p.textln("        BILL TOTAL: 4436.8")
p.textln("           TENDERD:    0.8")
p.textln("           BALANCE:  676.8")
p.textln(" --------------------------")
p.textln("         THANK YOU")
p.textln(" ===========================")

# Print QR code
p.set(align="center")
p.qr("Circuit Digest", native=True, size=12)

# Print barcode
p.textln("")
p.barcode('123456', 'CODE39')

# Cut paper (if supported)
p.cut()

print("Receipt printed successfully!")

Troubleshooting

Common Issues and Solutions

1. Printer Not Responding

Problem: Printer doesn't print anything

Solutions:

Check if hardware serial is enabled in raspi-config
Verify power supply is properly connected (9V, 1A minimum)
Connect TDR pin to GND
Check RX/TX connections (should be crossed)
Verify /dev/serial0 exists using ls -l /dev

2. Garbled Output

Problem: Printed text is unreadable or contains strange characters

Solutions:

Check baud rate matches (default: 9600)
Verify parity, stop bits, and data bits settings
Ensure proper encoding in Python code

3. Image Not Printing

Problem: Images don't appear on printed output

Solutions:

Ensure image width doesn't exceed 360 pixels
Use PNG or BMP format
Try different implementation: impl="bitImageColumn" or impl="bitImageRaster"
Check image file path is correct

4. Library Import Error

Problem: ModuleNotFoundError: No module named 'escpos'

Solutions:

sudo pip install python-escpos
# or
sudo pip3 install python-escpos

5. Serial Port Permission Denied

Problem: PermissionError: [Errno 13] Permission denied: '/dev/serial0'

Solutions:

sudo usermod -a -G dialout $USER
sudo reboot

Future Enhancements

Create dynamic receipt generation system
Integrate with database for inventory management
Add web interface for remote printing
Implement network printing capabilities
Create mobile app integration
Add support for multiple font styles
Implement automatic paper detection
Create receipt templates library

ESC/POS Commands

The thermal printer uses ESC/POS (Epson Standard Code for Point of Sale) commands. The python-escpos library abstracts these commands for easier implementation.

Common ESC/POS Functions:

Function	Description
`text()`	Print text
`textln()`	Print text with newline
`set()`	Set text properties
`image()`	Print image
`qr()`	Print QR code
`barcode()`	Print barcode
`cut()`	Cut paper
`ln()`	Line feed

Documentation: python-escpos Documentation

Additional Resources

Related Projects

Useful Links

Project Benefits

Cost-effective: No ink or toner required
Portable: Compact design suitable for mobile applications
Easy integration: Simple serial communication
Versatile: Supports text, images, barcodes, and QR codes
Long-lasting: Print head life up to 50 km
Low maintenance: Minimal upkeep required

Applications

Retail: Point of sale receipts
Healthcare: Patient reports and labels
Transportation: Ticket printing
Hospitality: Order receipts
Logistics: Shipping labels
Events: Entry tickets
Banking: Transaction receipts

Contributing

Feel free to contribute to this project by:

Reporting bugs
Suggesting new features
Submitting pull requests
Improving documentation

License

This project is open-source and available for educational and commercial purposes.

Acknowledgments

Circuit Digest for the comprehensive tutorial
python-escpos library developers
Raspberry Pi Foundation
MAXIM for thermal printer hardware

Contact & Support

For questions, issues, or suggestions:

Visit: Circuit Digest
Tutorial: Thermal Printer Interfacing with Raspberry Pi

Name		Name	Last commit message	Last commit date
Latest commit History 3 Commits
Thermal_Printer_with_Raspberry_Pi		Thermal_Printer_with_Raspberry_Pi
README.md		README.md

Circuit-Digest/Interfacing-Thermal-Printer-with-Raspberry-Pi

Folders and files

Latest commit

History

Repository files navigation

Thermal Printer Interfacing with Raspberry Pi

Project Overview

Table of Contents

Features

Components Required

About Thermal Printers

Technical Specifications

MAXIM PNP-500 Thermal Printer

Circuit Diagram

Pin Connections

Prerequisites

Hardware Setup

Software Requirements

Installation

Step 1: Enable Hardware Serial Port

Step 2: Verify Serial Port

Step 3: Install python-escpos Library

Step 4: Connect Hardware

Usage

Basic Initialization

Print Simple Text

Code Examples

1. Set Text Properties

2. Print Barcode

3. Print QR Code

4. Print Image

5. Text Alignment

Sample Receipt Output

Complete Receipt Printing Code

Troubleshooting

Common Issues and Solutions

1. Printer Not Responding

2. Garbled Output

3. Image Not Printing

4. Library Import Error

5. Serial Port Permission Denied

Future Enhancements

ESC/POS Commands

Common ESC/POS Functions:

Additional Resources

Related Projects

Useful Links

Project Benefits

Applications

Contributing

License

Acknowledgments

Contact & Support

About

Resources

Uh oh!

Stars

Watchers

Forks

Releases

Packages 0

Languages

Packages