RWD_QT Datasheet, PDF (2/19 Pages) rfsolutions.ltd – The MicroRWD “QT” (Quad-Tag) version is a complete 125kHz reader solution for Hitag 1,

ib technology
As with the individual MicroRWD versions, the RWD “QT” 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 up to 4k bits/second of data transfer
and the total time, for example, to read a Hitag 2 four-byte page, including reading of the
serial number, selecting the tag and the read operation itself takes less than 100ms.
The MicroRWD can be easily integrated into almost any application; when power (5v DC) is
first applied to the module the red and green LED outputs “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 output “flashing”
continuously until the fault has been rectified.
The MicroRWD will normally have the red LED output ON until a valid card or tag is
brought into the RF field. If the tag is accepted as valid then the green LED output is turned
ON (Red OFF) and the output drivers (OP0, OP1, OP2, OP3) are switched on. These outputs
can be connected together to give up to 100ma 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 drives directly.
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 transponder
for subsequent read/write operations. A simple serial protocol allows a host system to
communicate with the Micro RWD in order to program new authorised identity codes,
change internal parameters and perform read/write operations to the tag itself.
2) Standalone mode is where the 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 the four byte identity code is taken as the transponder serial
number (Page 0) for Hitag 1/S and Hitag 2 or memory bytes 1 - 4 on read-only types,
ignoring the most significant first byte (byte 0). Effectively standalone mode occurs
when there is no host system communicating with the Micro RWD.
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