EMPROT Datasheet, PDF (3/17 Pages) rfsolutions.ltd – Micro RWD EM4102 Low Power Version

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The communication protocol with the tags can achieve 2k bits/second of data transfer and the
total time to read the 40 bit data is less than 40ms.
The MicroRWD can be easily integrated into almost any application; when power (5v DC) is
first applied to the board the red and green LEDs flash once to indicate successful power-up.
The device can also check for broken or shorted antenna and can even detect very badly tuned
antennas; these problems are indicated by the red LED flashing continuously until the fault
has been rectified.
The MicroRWD will normally have the red LED lit until a valid card or tag is brought into the
RF field. If the tag is accepted as valid then the green LED is turned ON (and Red OFF) and
the output drives (OP2, OP3) are switched on. These outputs can be connected together to
give up to 50ma of drive current for operating an external load etc. If the auxiliary output
features are enabled then the UID (serial number) is transmitted as serial data or Weigand
protocol data on OP0, OP1 pins.
If the Beep delay is set then the “BEEP” output (pin 4) is pulsed ON/OFF. With auxiliary
output features turned OFF, the RWD responds to host commands on the TTL serial interface
at 9600 baud, 8 bits, 1 stop, no parity, as usual.
The Micro RWD has two basic modes of operation:-
Antenna
Micro RWD
Chip Module
RS232
Serial
comms
Antenna
Micro RWD
Chip Module
Standalone mode with
Internal EEPROM holding
authorised tag codes for
acceptance
Host System
Remote mode (connected to a host computer or microcontroller) and Standalone mode.
1) Remote mode involves connecting to a host serial interface. This is where the stored
list of authorised identity codes can be empty, effectively authorising any EM4102
transponder for subsequent read operations. A simple serial protocol allows a host
system to communicate with the Micro RWD in order to program new authorised
identity codes, change configurations and perform read operations from the tag itself.
2) Standalone mode is where the EM4102 tag identity codes are checked against a stored
list of authorised codes. If an identity code is matched, the output drives and Green
LED are enabled. In this case identity codes are taken as the least significant 4-
bytes of the EM4102 five byte sequence, The most significant first byte (byte 0) is
ignored. This is to allow use of any commercially supplied EM4102 transponders
where least significant bytes are incremented. Effectively standalone mode occurs
when there is no host system communicating with the Micro RWD.
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