HydraBus is an Open Source Hardware STM32 Devkit with Support for NFC via HydraNFC Shield

Recently, I wrote about the public availability of a MicroPython board based on STMicro STM32F4 Cortex M4 support that can easily be programmed with Python. It turns out there’s another STM32 board called HydraBus, also supporting Micro Python firmware, or another embedded firmware based on ChibiOS, together with an optional HydraNFC shield capable of sniffing, reading/writing or emulating any 13.56MHz NFC tags.



HydraBus Specifications:

  • MCU – STMicro TM32F405RG micro-controller @ 168 MHz with 1MB flash, 192KB SRAM, and an FPU.
  • External Storage – Micro SD card slot up to 48MHz (~24MB/s)
  • Expansion Headers – 4 headers with access to 44 I/Os (some already used by micro SD and USB 1 & 2).
  • USB – 2x micro USB connector including 1x OTG port, and 1x device/host port, both with ESD protection.
  • Misc – Reset and user button, user LED,
  • Power – 5V via micro USB port.
  • Dimensions – 60mm x 37mm (compliant with a Dangerous Prototype DP6037 PCB size)

As mentioned in the introduction, there are two firmware files for the board, both with source code available on Github: MicroPython and a HydraFW based on ChibiOS. The board is also open-source hardware with CadSoft Eagle 6.x schematics & PCB layout, BoM, and Gerber files available on Github too, and licensed under Creative Commons BY NC.



If you’d like to “play” with NFC, Benjamin Vernoux, HydraBus’ developer, has also designed HydraNFC shield for HydraBus board with the following hardware specs:

  • Autonomous mode with 4 User buttons and 4 User LEDs.
  • Use HydraBus microSD card to save or load data – Support of microSD (FAT16/FAT32) card up to 32GB (tested with SanDisk Extreme 32GB).
  • Use Texas Instrument TRF7970A NFC chipset with full access to all pins and all modes of TRF7970A through connectors J1/J2/J3.
  • HydraBus Antenna (external) with U.FL connector(cable included) or SMA (optional) and can read Mifare card at up to 8cm (with 20cm cable).

Firmware support is achieved via HydraFW running on STM32 MCU. HydraNFC is also open-source hardware, and you’ll find the hardware design files in hydranfc repository.

More details are available on Hydrabus.com. You can purchase the boards directly on the website, or via Seeed Studio for $49 and $79 for respectively HydraBus and HydraNFC boards.

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