Thermal printer technology has revolutionised receipt printing in retail, healthcare, and IoT projects. This comprehensive tutorial shows you how to interface popular thermal printers like the PNP-500 with ESP32 and Arduino, enabling receipt, barcode, and QR code printing.
Project Overview
- Build Time: 3-5 hours
- Cost: $30-50
- Difficulty: Beginner–Intermediate
- What You'll Learn: UART communication, ESC/POS commands, bitmap image printing, QR & barcode generation
- Applications: IoT monitoring, smart home automation, receipt systems, barcode labelling
Understanding Thermal Printer Technology
What is Thermal Printer: Basics
Thermal printers use heat-sensitive paper instead of ink. A heated print head creates text or images by darkening specific dots on the paper.
Key Benefits:
- Paper sizes: 57mm, 76mm, 80mm, and 110mm widths
- Key advantages: No ink required, silent operation, fast printing
PNP-500 Thermal Printer for ESP32 and Arduino
The PNP-500 is a compact panel-mount thermal printer, commonly used in diagnostic equipment and embedded systems.
Technical Specifications of thermal printer:
- Print Width: 48mm
- Speed: 50–80 mm/sec
- Resolution: 384 dots/line (8 dots/mm)
- Interfaces: TTL UART, RS232, USB
- Voltage: 5–9V DC (works best at >6V)
- Print Head Life: 50 km of printing
What are the advantages of using an ESP32 with a thermal printer?
Pairing a thermal printer with ESP32 offers several benefits:
- Cost-effective: No ink or toner needed, just thermal paper
- Compact design: Small printer + ESP32 fits into handheld or IoT devices
- Wireless connectivity: ESP32 adds Wi-Fi/Bluetooth for mobile app or cloud service integration
- Performance: Fast and quiet operation, perfect for on-demand receipts, labels, or alerts
- Versatile printing: Supports text, barcodes, QR codes, and bitmaps with simple commands
What can you build with ESP32 and Thermal Printer?
- IoT monitoring devices (print real-time data logs)
- Smart home status printers (daily to-do lists, reminders)
- Portable receipt printers
- Barcode/QR code label makers
Hardware Requirements
- ESP32 Development Board
- Thermal Printer (PNP-500 / RS203)
- Resistors (1kΩ × 2)
- Breadboard + Wires
- 2S Li-ion Battery (for printer)
- Push Buttons × 2 (optional)
Circuit Connection Guide
ESP32 Thermal Printer Circuit Diagram
How to Connect the Thermal Printer to ESP32
- Use UART (TTL pins) on the printer
- ESP32 pin connections (example):
- RXD2 → Printer TX
- TXD2 → Printer RX
- GND and Vcc as required
Important Notes:
Use pull-up resistors on RX/TX to reduce interference
Printer needs separate power (Li-ion battery recommended)
Programming Your ESP32 Thermal Printer
Thermal printers understand ESC/POS commands over serial (UART). You can print bitmaps, barcodes, and QR codes using simple commands.
Source Code
Full source code is available on GitHub:
ESP32 Thermal Printer GitHub Repo