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  1. JP GNSS HAT
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JP GNSS HAT

Driver library for Jimmy Paputto GNSS HATs on Raspberry Pi. Handles the full u-blox UBX protocol and provides a high-level API in C++, C, and Python.

Buy our HATs at jimmypaputto.com — if you have custom u-blox hardware, most of the code will still be useful.

Supported Hardware

The library auto-detects the HAT variant via /proc/device-tree/hat/product.

HAT u-blox Module Interface USB RTK Time Base Time Mark Geofencing
L1 GNSS HAT NEO-M9N SPI Yes — — — Up to 4 zones
L1/L5 GNSS TIME HAT NEO-F10T UART — — Survey-In / Fixed Position EXTINT GPIO 17 —
L1/L5 GNSS RTK HAT NEO-F9P SPI + UART Yes Base & Rover — — Up to 4 zones

Key Features

  • Multi-language API — C++ (IGnssHat interface), C (jp_gnss_hat_* functions), Python (CPython extension)
  • Full UBX protocol — NAV-PVT, NAV-SAT, NAV-DOP, MON-RF, NAV-GEOFENCE, TIM-TM2
  • RTK support — centimeter-level positioning with RTCM3 base/rover corrections
  • Time base — nanosecond-accurate timing with Survey-In or Fixed Position
  • Time mark — precise EXTINT event timestamping via UBX-TIM-TM2
  • Geofencing — up to 4 circular zones with PIO pin output
  • Jamming detection — per-band RF interference monitoring
  • GPSD integration — NMEA forwarding to virtual serial port
  • Thread-safe — event-driven, mutex-protected, no busy-wait loops
  • 1–25 Hz measurement rate

Project Structure 

GnssHat/
├── src/
│   ├── GnssHat.hpp / .cpp          C++ API and implementation
│   ├── GnssHat.h / GnssHat_C.cpp   C API wrapper
│   ├── ublox/                       UBX protocol, drivers, parsers, data structures
│   └── common/                      GPIO, synchronization, utilities
├── python/                          Python CPython extension module
├── examples/                        C, C++, Python examples + Visualization + GPSD + TimeServer
│   └── BinariesSymlinks/            Symlinks to C++ binaries (created by BUILD_EXAMPLES)
└── scripts/                         Build and dependency scripts