HydraFW is a native C (and asm) open source firmware for HydraBus board with support of HydraNFC Shield.
This version is basic and mainly for HydraNFC users waiting sniffer mode for NFC ISO/IEC 14443 Identification cards.
The firmware can be installed without recompilation (dfu binary included) by following the 7 steps to flash their HydraBus board.
It is available on github:
https://github.com/bvernoux/hydrafw