EMPROT Datasheet, PDF (14/17 Pages) rfsolutions.ltd – Micro RWD EM4102 Low Power Version

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Weigand 26 bit sequence:- E (b0 --------- b11) (b12 -------- b23) O
E (0 4 6 0 2 2)O
1 0000 0100 0110 0000 0010 0010 1
Where E is EVEN parity bit for bit 0 to 11 and O is ODD parity bit for bits 12 to 23
The base data for the Weigand output is the least significant 4-bytes of the EM4102 or
MCRF200/123 tag data. EM4102 or MCRF200/123 Reader mode selection is by means of an
RWD EEPROM parameter. In addition, parameters control whether the base data byte order
is reversed or if parity bits are added before output.
The complete data frame is output whenever the tag is within the RWD’s antenna field and
the tag has been validated. This output is independent of the normal TTL serial interface
which responds to received commands and replies with the data as requested.
The physical Weigand protocol is asynchronously transmitted as 50 µS LOW pulses on the
appropriate DATA low or DATA high pins. These pulses are separated by 2mS periods. The
Weigand sequence is output a single time whenever a valid tag enters the RF field for the first
time. (NO Weigand output if AUX OUTPUT parameter is ZERO/OFF).
DATA High
Weigand Protocol Timing Diagram
50 µS pulse
DATA Low
2mS pulse intervals
DATA
1
0
1
0
5v
0v
TTL level
5v
0v
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