R
EM4223
Command
Code
(6 bits)
Parameters
& Flags
(4 bits)
1st Optional
Parameter
(8 bits)
2nd Optional
Parameter
(0-136 bit)
RFU
(1 bit)
CRC-5
(5 bits)
CRC-16
EOF
SOF
16 bits
Fig. 4 - General format, Extended commands
The 2 Extended commands supported by the EM4223
are used to all selected sub-populations of Tags to be
introduced to the Arbitration process.
During reception of a command, and until the command
has been correctly received, the Transponder will hold-
off any attempt to reply until the command has been
correctly received and executed. At the end of receiving
a command, if it has not been correctly decoded, the
Transponder will remain in the ROUND_STANDBY state
until moved out of this state by the first correctly received
and decoded command.
Implied MUTE command (Fast Supertag Mode only)
When operating in the Fast Supertag Mode and in the
ACTIVE state, the reception of the first low-going pulse
of any command causes the EM4223 to move to the
ROUND_STANDBY state. This could be any single pulse
or the first pulse of the SOF of a valid command. The
Transponder will continue to decode the command. A
known and valid command causes the Transponder to
execute the command and to move to either the
ROUND_ACTIVE or the READY state, depending on the
command and its parameters (if any). An unknown
command or a command having an error will cause the
Transponder to remain in the ROUND_STANDBY state.
If the Tag is in the Fast Supertag Mode and in the TTF
(Tag Talks First) sub-mode (Wake Up Status Flag =
X00), the Tag will automatically leave the
ROUND_STANDBY state after a timeout period of 2.5 X
176 tag bit periods has elapsed since the last MUTE
command (176 bits = maximum Tag Data Message
length).This timeout will be reset each time a new implied
MUTE command is received.
Command
Protocol
Extension
Op-
Code
6
Parameter / flags
4 bits
CRC-5
Extended
parameters
CRC-16
Comments
bits
Init-Round
Always = 0
01
SUID
1 bit
Round
Size
3 bits
5 bits
AFI
8 bits
16 bits
SUID = 0 tag responds with
the 128 bits of user data.
SUID = 1 tag responds with
SUID. If AFI field = 00H, all
tags respond, else if AFI is
other value, only tags with
matching AFI respond. Also
moves tags already active in
FST mode to ISO mode.
The signature must match the
signature value transmitted by
the tag in its last reply to
acknowledge the tag’s reply.
Advances the CURRENT
SLOT COUNTER.
Next-Slot
Always = 0
02 *
Signature 4 bits
5 bits
Close Slot
Always = 0
Always = 0
03
Ignored by
EM4223
Ignored by
EM4223
5 bits
5 bits
Advances the CURRENT
SLOT COUNTER.
Standby-
Round
04 *
The signature is not used in
this implementation because
the EM4223 has no select
state. The EM4223 will always
move to the
ROUND_STANDBY state.
New-Round
Always = 0
05
SUID
1 bit
Round
size
5 bits
3 bits
Reset-To-
Ready
Init-Round-
All
Always = 0
Always = 0
06 *
0A *
Ignored by
EM4223
SUID
5 bits
5 bits
Moves Transponder from
current state to READY state.
SUID = 0 tag responds with
the128 bits of user data. SUID
= 1 tag responds with SUID.
Also moves tags already
active in FST mode to ISO
mode.
Round
size
3 bits
1 bit
7
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