GCA41 Arduino nano shield RFID-interface for RC522


By Peter Giling


Using RFID is very much a system that enables you to indicate all rolling stock on the rails, without
the need of drawing power from the rails.
RFID is widely known in all situations like securety, shop lifting protection, and many others.
RFID with Rocrail started with the idea of MERG in England , using ID-12 sensors.
Rocrail reacted on that with the introduction of CAN-GC4 for CBUS, and with an input for
the same ID-12 on the Raspberry Pi HAT GCA_PI01.
The sensed information is transmitted with 9600 Bd.
But the ID-12 is expensive and rather slow, and also it is very easy to disturb with the noise of
the motor inside your locomotive.
This is mainly due to the frequency of 125 KHz it is running on
Now a better solution is optioned by using a rather cheap RC522. widely available around the world.
It runs on 13.56 MHz, which makes a lot better protection against electrical motor noise,
and also increases the reading speed sincerely.
But that sensor type is not an active type like the ID-12, meaning that
it will sense much faster the nearing of a tag, stores its number , but that's it.
It will not pass this information through until it is asked for, so we need a bidirectional communication
to get the value of the tag, and, if available, pass it through to CAN-GC4 and/or GCA_PI01.
CAN-GC4 was not made for that, not possible even, and for LNet there was no solution anyway.
The development of such a little interface was pretty easy since there are Arduino nano boards to fix that.
This GCA41 board is just a shield for an Arduino Nano, creating an interface between RC522 sensor and CAN-GC4 or GCA_PI01.
Communication between Nano and RC522 is done by SPI, which guarantees suitable speed .
For use of RFID with LNet, please refer to GCA51.


The pcboard and parts positions
Partslist GCA41
R1 Resistor 1 Kohm
R2 Resistor 470 Ohm
C1 Elco 100 uF minimum 16 Volt radial
D1 Led 3mm
S1 PSS 254-3G
RC522 PSS 254-8G
U1 Arduino Nano

Firmware sources

The sources for Arduino Nano sketch

Extra feature for Window users only! (as far as I know).
To make it simple for programming the Nano.
The zip file above also contains a rfid2_ser.ino.eightanaloginputs.hex file.
Download, install and execute the program Xloader here www.hobbytronics.co.uk_arduino-xloader
Then use it to program the hex. file via USB, no Arduino program needed.

How to connect and use RC522 RFID sensor board

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