H1W200102 Datasheet, PDF (3/10 Pages) rfsolutions.ltd – Micro RWD H1 “Wiegand” Output Version

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MicroRWD Hitag 1 operation
The MicroRWD H1 (Wiegand) version is also a complete read and write tag acceptance
solution for Hitag 1 RF transponders. The module provides internal EEPROM memory for
holding lists of authorised identity codes, a manual override switch facility and has LED
drives to give visual indication of acceptance as well as having the Wiegand protocol outputs.
The RWD also has a TTL level RS232 interface that allows a host system to communicate
with the RWD if necessary, so that system features can be customised, configurations
changed and tag read/write data handled by the host system.
The Hitag 1 transponders have significantly more memory than most other tags and provide
2048 bits (256 bytes) of EEPROM memory arranged as partitioned 32 bit pages. An area of
1536 bits (192 bytes) is open for general user data. The communication protocol (handled
entirely by the RWD) supports multiple tags in the RF field and data integrity and security is
ensured using extensive CRC (Cyclic Redundancy Check) methods and highly encrypted data
storage.
The MicroRWD is essentially a proximity system and a Read/Write range of up to 20cm can
be achieved with the same level of reliable communication and EMC resilience. The unique
AST (Adaptive Sampling) feature allows the RWD to continually adjust and re-tune the
sampling to allow for inductive changes in the RF field, an essential feature for real-world
reliability and robust operation. The communication protocol with the tags can achieve 4k
bits/second of data transfer and the total time to read a 32 bit page, including reading of the
serial number, selecting the tag and the read operation takes less than 100ms.
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 lit and the output driver (OP2) is
switched on. This provides up to 25ma of drive current for operating a relay etc. In addition, a
switch input is provided for overriding the tag reading operation and switching the output
drive directly. When the green LED is lit the tag serial number is also output as Wiegand
protocol on the DATA high and DATA low outputs (OP0, OP1) and the OP3 line is pulsed
high for a two second period (to operate a buzzer and allow separation of Wiegand data
frames). This Wiegand data is only output a single time while the valid card is in the RF field.
If the Wiegand data length is ZERO (as programmed into the RWD internal memory) then
there is no Wiegand output and OP3 remains low. In this case the RWD serial commands still
operate in the usual manner.
(Hitag 1 is a trademark of Philips Semiconductors)
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