Introduction
PayDeck is an open-source, watch-only point-of-sale terminal designed to make accepting Nexa (NEXA) simple, secure and practical for real-world merchants. Running on affordable ESP32 touchscreen hardware, PayDeck acts as a dedicated NEXA payment receiver: it displays amounts, generates QR codes, and monitors the network for incoming transactions, all without storing private keys. This architecture keeps the terminal secure, auditable and easy to deploy in shops, cafés or event environments.
The project is fully transparent and all documentation, firmware and development resources are available at https://paydeck.org, and the GitLab repository. The website also lists hardware recommendations and suppliers, including direct links to the exact supported boards, making it straightforward for users to assemble a working PayDeck unit.
Technical Features
PayDeck provides a practical, security-focused feature set tailored for NEXA payments:
• Touch-based graphical interface (TFT_eSPI + XPT2046)
• Optional 12-word mnemonic seed generation for deriving xpubs
• Support for importing existing xpubs or manually entering addresses
• Automatic Wi-Fi shutdown while handling sensitive seed material
• Real-time invoice/status tracking via Rostrum
• Nexa BIP-21 URI generation and QR code rendering
• ESP-IDF Secure Boot and Flash Encryption support
• SNTP-based time synchronization for accurate timestamps
• Append-only CSV logs with rolling SHA-256 checksum for tamper evidence
Hardware Requirements
Supported hardware is inexpensive and widely available. A recommended board can be purchased here:
https://www.aliexpress.com/w/wholesale-ESP32-Arduino-LVGL-WIFI%26Bluetooth-2.8-TFT-Display.html
| Component | Description |
|---|---|
| ESP32 Board | e.g., ESP32-2432S028R (“Cheap Yellow Display”) |
| TFT Display | 240×320, ST7789 driver (HSPI) |
| Touch Controller | XPT2046 (VSPI, CS=33, IRQ=36) |
| Power Source | 5V via USB or external supply |
| Optional | USB cable for flashing, stable Wi-Fi network |
Build Instructions (PlatformIO Recommended)
Supported environments: PlatformIO or Arduino IDE
Recommended: PlatformIO
1. Install prerequisites
Install Visual Studio Code + PlatformIO extension.
2. Clone the repository
git clone https://gitlab.com/IamEndo/paydeck.git
cd paydeck/
3. Connect your ESP32 and identify the serial port:
-
Windows → COM3, COM4, …
-
macOS → /dev/tty.SLAB_USBtoUART
-
Linux → /dev/ttyUSB0
4. Build and flash the firmware
pio run -t upload -e esp32dev-hspi-ili9341
5. Open the serial monitor
pio device monitor -b 115200
You should then see the boot log and the PayDeck splash screen.
Legal and Licensing
• License: MIT (see LICENSE)
• Status: Beta software provided “AS IS” without warranty
• Classification: Non-custodial display-only terminal, not a payment processor
• Privacy: No personal data collected
• Export: Standard public cryptography (SHA-256, secp256k1, BIP-32)
We welcome the entire NEXA ecosystem to participate: try PayDeck, build your own unit, contribute improvements or propose integrations that help expand merchant adoption. Join the community on Telegram (https://t.me/paydeckproject) and follow updates on X/Twitter (https://x.com/PayDeckProject). Your feedback and involvement will help shape the next phase of PayDeck’s development.