sri4k STMicroelectronics, sri4k Datasheet - Page 21

• Manufacturer Part Number: sri4k
• Description: 13.56 Mhz Short-range Contactless Memory Chip With 4096-bit Eeprom And Anticollision Functions
• Manufacturer: STMicroelectronics

SRI4K
6
6.1
6.2
6.3
6.4
6.5
SRI4K states
The SRI4K can be switched into different states. Depending on the current state of the
SRI4K, its logic will only answer to specific commands. These states are mainly used during
the anticollision sequence, to identify and to access the SRI4K in a very short time. The
SRI4K provides 6 different states, as described in the following paragraphs and in
POWER-OFF state
The SRI4K is in POWER-OFF state when the electromagnetic field around the tag is not
strong enough. In this state, the SRI4K does not respond to any command.
READY state
When the electromagnetic field is strong enough, the SRI4K enters the READY state. After
Power-up, the Chip_ID is initialized with a random value. The whole logic is reset and
remains in this state until an INITIATE() command is issued. Any other command will be
ignored by the SRI4K.
INVENTORY state
The SRI4K switches from the READY to the INVENTORY state after an INITIATE()
command has been issued. In INVENTORY state, the SRI4K will respond to any
anticollision commands: INITIATE(), PCALL16() and SLOT_MARKER(), and then remain in
the INVENTORY state. It will switch to the SELECTED state after a SELECT(Chip_ID)
command is issued, if the Chip_ID in the command matches its own. If not, it will remain in
INVENTORY state.
SELECTED state
In SELECTED state, the SRI4K is active and responds to all READ_BLOCK(),
WRITE_BLOCK() and GET_UID() commands. When an SRI4K has entered the
SELECTED state, it no longer responds to anticollision commands. So that the reader can
access another tag, the SRI4K can be switched to the DESELECTED state by sending a
SELECT(Chip_ID2) with a Chip_ID that does not match its own, or it can be placed in
DEACTIVATED state by issuing a COMPLETION() command. Only one SRI4K can be in
SELECTED state at a time.
DESELECTED state
Once the SRI4K is in DESELECTED state, only a SELECT(Chip_ID) command with a
Chip_ID matching its own can switch it back to SELECTED state. All other commands are
ignored.
SRI4K states
Figure
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19.