MAX66140 Maxim, MAX66140 Datasheet - Page 10

• Manufacturer Part Number: MAX66140
• Description: The MAX66140 combines 1024 bits of user EEPROM with secure hash algorithm (SHA-1) challenge-and-response authentication (ISO/IEC 10118-3 SHA-1), a 64-bit unique identifier (UID), one 64-bit secret, and a 13
• Manufacturer: Maxim

ISO 15693-Compliant Secure Memory
Initially, the master has no information whether there are
any RF devices in the field of its antenna. The master
learns the UIDs of the slaves in its field from the
responses to the Inventory command, which does not
use the Address_flag and the Select_flag bits. The state
transitions are controlled by network function com-
mands. Figure 16 shows details.
ISO 15693 defines four states in which a slave can be
plus three address modes. The states are power-off,
ready, quiet, and selected. The address modes are
nonaddressed, addressed, and selected. The
addressed mode requires that the master include the
slave’s UID in the request, which increases the size of
the requests by 8 bytes. Table 5 shows which address
mode is applicable depending on the slave’s state and
how to set the Address_flag and the Select_flag bits for
each address mode.
This state applies if the slave is outside the master’s RF
field. A slave transitions to the power-off state when
leaving the power-delivering RF field. When entering
the RF field, the slave automatically transitions to the
ready state.
In this state, a slave has enough power to perform any
of its functions. The purpose of the ready state is to
have the slave population ready to process the invento-
ry command as well as other commands sent in the
addressed or nonaddressed mode. A slave can exit the
Table 5. Slave States and Applicable Address Modes
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SLAVE STATES
Power-Off
ISO 15693 Slave States and
Selected
Ready
ISO 15693 States and Transitions
Quiet
ABRIDGED DATA SHEET
Address Modes
NONADDRESSED MODE
(Address_flag = 0;
Select_flag = 0)
Power-Off State
(Inactive)
Yes
Yes
No
Ready State
ready state and transition to the quiet or the selected
state upon receiving the Stay Quiet or Select command
sent in the addressed mode.
In this state, a slave has enough power to perform any
of its functions. The purpose of the quiet state is to
silence slaves that the master does not want to commu-
nicate with. Only commands sent with the addressed
mode are accepted and processed. This way the mas-
ter can use the nonaddressed mode for communication
with remaining slaves in the ready state, which mini-
mizes the size of the request data packets. As long as
no additional slaves arrive in the RF field, it is safe for
the master to continue communicating in the nonad-
dressed mode. A slave can exit the quiet state and
transition to the ready or the selected state upon receiv-
ing the Reset to Ready or Select command sent in the
addressed mode.
In this state, a slave has enough power to perform any
of its functions. The purpose of the selected state is to
isolate the slave that the master wants to communicate
with. Commands are accepted and processed regard-
less of the address mode in which they are sent, includ-
ing the Inventory command. With multiple slaves in the
RF field, the master can put one slave in the selected
state and leave all the others in the ready state. This
method requires less communication than using the
quiet state to single out the slave for communication.
For a slave in the selected state, the master can use the
selected mode, which keeps the request data packets
as short as with the nonaddressed mode. A new slave
entering the RF field cannot disturb the communication,
since it stays in the ready state. A slave can exit the
ADDRESSED MODE
ADDRESS MODES
(Address_flag = 1;
Select_flag = 0)
(Inactive)
Yes
Yes
Yes
SELECTED MODE
(Address_flag = 0;
Select_flag = 1)
(Inactive)
Yes
No
No
Selected State
Quiet State