cflegel/nerves_io_rc522

RC522 RFID reader support for Nerves

Nerves.IO.RC522

Nerves support for the RC522 RFID reader.

The RC522 is a cheap RFID module which can be used to read MIFARE-compatible tags at 13.56Mhz.

Combined with a Raspberry Pi, this makes for a pretty compact RFID reader. The RC522 board is so small it easily fits inside most Raspberry Pi cases.

Limitations

Currently, only Raspberry Pi is supported as the host platform due to the usage of the BCM2835 library in the Port driver.

Furthermore, this library currently only reads the tag UID. The RC522 supports reading and writing MIFARE tag data, but this library does not yet support it.

Installation

1. Add nerves_io_rc522 to your list of dependencies in mix.exs:

```elixir
def deps do
  [{:nerves_io_rc522, "~> 0.1.0"}]
end
```

2. Ensure nerves_io_rc522 is started before your application:

```elixir
def application do
  [applications: [:nerves_io_rc522]]
end
```

Usage

Add the Nerves.IO.RC522 GenServer to your supervision tree:

{Nerves.IO.RC522, {RfidReader.Handler, :tag_scanned}}

When a tag is scanned the function RfidReader.Handler.tag_scanned() function will now be called with the hex-encoded serial number (UID) of the scanned tag as its single argument.

Connecting the hardware

Connecting RC522 module to SPI is pretty easy. You can use this neat website for reference.

Board pin name	Board pin	Physical RPi pin	RPi pin name
SDA	1	24	GPIO8, CE0
SCK	2	23	GPIO11, SCKL
MOSI	3	19	GPIO10, MOSI
MISO	4	21	GPIO9, MISO
GND	6	6, 9, 20, 25	Ground
RST	7	22	GPIO25
3.3V	8	1	3V3

License

The Elixir code of this library is distributed under the Apache license.

The files in the src directory contain the rc522 port driver, which is distributed as GPLv2, as it incorporates the BCM2835 driver library. See src/COPYING for the GPL license.