H2PROT Datasheet, PDF (3/9 Pages) rfsolutions.ltd – Typical application configuration for Micro RWD module

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Supported transponder types
The Micro RWD H2 version is designed to communicate with Hitag 2 transponders
configured in PASSWORD mode. Setting the HT2 transponder to any other
configuration will render them inoperable with this system. The operation of the Micro
RWD and Hitag 2 transponders is described in more detail at the end of this document.
The identification codes described in this text are regarded as the first four bytes (serial
number or page 0) of the tag memory array.
Serial Interface
This is a basic implementation of RS232. The Micro RWD does not support buffered
interrupt driven input so it must control a BUSY (CTS) line to inhibit communications
from the host when it is fully occupied with tag communication. It is assumed that the
host (such as a PC) can buffer received data.
Tx, Rx and RTS signals from the Micro RWD are all TTL level and can be converted to
+/-10v RS232 levels using an inverting level converter device such as the MAX202
(note the inversion of the TTL levels).
The serial communication system and protocol allows for a 10ms ‘window’ every Tag
polling cycle indicated by the BUSY line being low. During this ‘window’ the host must
assert the first start bit and start transmitting data. The BUSY goes high again 10ms after
the last stop bit is received. NOTE that only one command sequence is handled at a
time.
Transmitted or Received data byte, 9600 baud, 8 bit, 1 stop, No parity (104uS per bit)
b0 b1 b2 b3 b4 b5 b6 b7 b8 b9
5v
1
0
TTL levels
0v
idle START
8 bit data
STOP idle
RWD tag polling cycle and serial communication BUSY protocol
RWD 5v
BUSY
0v
RWD 5v
RX
0v
RWD 5v
TX
0v
Ready to Receive
Busy
RWD cannot receive CMD or DATA
Ready to Receive
CMD/DATA
CMD/DATA
Host must Transmit CMD/DATA within 10mS of BUSY going low
Polling delay (100mS to 600mS)
100mS default
DATA
3