ib technology

3

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:-

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.

Antenna

Antenna

Micro RWD

Chip Module

Micro RWD

Chip Module

Host System

RS232

Serial

comms

Standalone mode with

Internal EEPROM holding

authorised tag codes for

acceptance