SRT512 datasheet(21/49 Pages) STMICROELECTRONICS

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SRT512

SRT512 states

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SRT512 states

The SRT512 can be switched into different states. Depending on the current state of the

SRT512, its logic will only answer to specific commands. These states are mainly used

during the anticollision sequence, to identify and to access the SRT512 in a very short time.

The SRT512 provides 6 different states, as described in the following paragraphs and in

Figure 17.

6.1

POWER-OFF state

The SRT512 is in POWER-OFF state when the electromagnetic field around the tag is not

strong enough. In this state, the SRT512 does not respond to any command.

6.2

READY state

When the electromagnetic field is strong enough, the SRT512 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 SRT512.

6.3

INVENTORY state

The SRT512 switches from the READY to the INVENTORY state after an INITIATE()

command has been issued. In INVENTORY state, the SRT512 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 SRT512 is active and responds to all READ_BLOCK(),

WRITE_BLOCK(), and GET_UID() commands. When an SRT512 has entered the

SELECTED state, it no longer responds to anticollision commands. So that the reader can

access another tag, the SRT512 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 SRT512 can be in

SELECTED state at a time.

6.5

DESELECTED state

Once the SRT512 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.

SRT512 Datasheet(PDF) 21 Page - STMicroelectronics