ST25TB02K datasheet(16/47 Pages) STMICROELECTRONICS

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ST25TB02K states

The ST25TB02K can be switched into different states. Depending on the current state of the ST25TB02K, its logic

will only answer to specific commands. These states are mainly used during the anticollision sequence, to identify

and to access the ST25TB02K in a very short time. The ST25TB02K provides 6 different states, as described in

the following paragraphs and in Figure 15.

6.1

Power-off state

The ST25TB02K is in Power-off state when the electromagnetic field around the tag is not strong enough. In this

state, the ST25TB02K does not respond to any command.

6.2

Ready state

When the electromagnetic field is strong enough, the ST25TB02K 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 ST25TB02K.

6.3

Inventory state

The ST25TB02K switches from the Ready to the Inventory state after an Initiate() command has been

issued. In Inventory state, the ST25TB02K 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.

6.4

Selected state

In Selected state, the ST25TB02K is active and responds to all Read_block(), Write_block() and Get_UID()

commands. When an ST25TB02K has entered the Selected state, it no longer responds to anticollision

commands. So that the reader can access another tag, the ST25TB02K can be switched to the Deselected

state by sending a Select(Chip_ID) 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 ST25TB02K can be in Selected state at a time.

6.5

Deselected state

Once the ST25TB02K 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.

ST25TB02K

ST25TB02K states

DS11469 - Rev 7

page 16/47

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