R
EM4223
Transponders will only transmit Data Messages to the
Reader while they are in the ROUND_ACTIVE state.
When the CURRENT SLOT NUMBER and the
SELECTED SLOT NUMBER values held by the
Transponder match, the Transponder transmits its Data
Message to the Reader. The Reply message will contain
either the SUID (the Integrated Circuit Manufacturer code
of 0x16 for MARIN and the lower 32 bits of the 128 bit
User Data) or the 128 bit User Data .
In situations where different groups of transponders
present in the reader field contain data having different
owners, a reader may selectively wake up these different
groups of transponders by means of the ISO compliant
AFI parameter in the Init_Round command or by using the
Mask parameter in the Begin_Round command. The
Begin_Round command additionally supports selection of
groups of transponders based on the user data content
according to the EPC™ method.
General Command Format
All commands are transmitted from the Reader to the
Transponder by means of pulse interval encoding as
defined in chapter
5: forward link encoding,
beginning with
an SOF (Start Of Frame) and terminating in an EOF (End
Of Frame). Commands are supported in accordance with
the ISO 18000-6A specification which divides commands
into the categories of MANDATORY, OPTIONAL,
CUSTOM and PROPRIETARY. The EM4223 supports all
of the ISO 18000-6A MANDATORY commands and 4 of
the ISO 18000-6A OPTIONAL commands – Init_Round,
Close_Slot, New_Round and Begin_Round. In addition,
the EM4223 implements 1 PROPRIETARY command in
accordance with the ISO 18000-6A specification – this is
the Wake_Up_FST command which uses Op-Code 0x39.
Commands are divided into 2 basic types: Short
Commands of a fixed 16 bit length and Extended
commands which consist of a 16 bit section consistent
with the Short Command format followed by a variable
length extension containing various parameters and a
second CRC of 16 bit length which covers the entire
st
command, including the 1 11 bits which will already have
been covered by the 5 bit CRC and the 5 bit CRC itself.
The BEGIN_ROUND command is included for Supply
Chain Logistics support.
In addition to the above, the Fast Supertag™ commands:
WAKE_UP_FST and MUTE are supported for compliance
with the FST protocol. MUTE is interpreted as any
partially decoded or invalid command as described in
section 0.
56H
3. BASIC COMMAND FORMATS
There are 7 short commands, 2 extended commands and
1 implied command.
Short commands
Short commands are a fixed length of 16 bits, which
includes a 5 bit CRC. The commands comprise the
following fields:
Protocol extension – 1 bit.
Command Op-code – 6 bits.
Parameters – 4 bits (parameters could include flags).
CRC – 5 Bits.
SOF
RFU
(1 bit)
Command
Code (6 bits)
Parameters &
Flags (4 bits)
CRC-5
(5 bits)
EOF
Fig. 3 General format, Short commands
Short commands are used for collision arbitration and
other immediate functions.
Supported Command set
The EM4223 fully supports the four ISO MANDATORY
commands:
NEXT_SLOT,
STANDBY_ROUND,
RESET_TO_READY and INIT_ROUND_ALL.
The ISO OPTIONAL commands: INIT_ROUND,
CLOSE_SLOT, and NEW_ROUND are also supported.
Extended commands
The EM4223 supports 2 Extended commands
(Init_Round and
Begin_Round).
They comprise a fixed
length part of 16 bits, which is identical with the format of
the 16 bit Short Commands described above, followed by
an 8 bit fixed length parameter in the case of both of the
nd
Extended commands, followed by a 2 parameter of
variable length up to 136 bits and terminated with a 16 bit
CRC. The Extended commands comprise the following
fields:
Protocol extension – 1 bit.
Command Op-code – 6 bits.
Parameters – 4 bits (parameters could include flags).
CRC – 5 Bits.
Extension of 8 bits (AFI) in the case of the
INIT_ROUND
command,
or
an
8
bit
(MASK_LENGTH) parameter followed by a variable
length (MASK) parameter in the case of the
BEGIN_ROUND command
CRC-16 :- 16 Bits (over full message from after the
SOF to the last bit before the CRC16 itself).
Copyright
©
2005, EM Microelectronic-Marin SA
6
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EMMICRO [ EM MICROELECTRONIC - MARIN SA ]
