USER MANUAL
STM 550X / EMSIX
–
ENOCEAN MULTI-SENSOR
© 2020 EnOcean | www.enocean.com F-710-017, V1.0
STM 550x / EMSIx User Manual | v1.0 | February 2020 | Page 42/79
7.4.2
IDLE state
IDLE is the waiting state after a Power-On Reset (POR), i.e. after the NFC tag has been in-
troduced into the magnetic field of the NFC reader.
The NFC tag exits the IDLE state towards the READY 1 state when either a REQA or a WUPA
command is received from the NFC reader. REQA and WUPA commands are transmitted by
the NFC reader to determine whether any cards are present within its working range.
Any other data received by the NFC tag while in IDLE state is discarded and the NFC tag
will remain in IDLE state.
7.4.3
READY 1 state
READY 1 is the first UID resolving state where the NFC tag resolves the first 3 bytes of the
7 byte UID using the ANTICOLLISION or SELECT commands for cascade level 1.
READY 1 state is exited after the SELECT command from cascade level 1 with the matching
complete first part of the UID has been executed. The NFC tag then proceeds into READY 2
state where the second part of the UID is resolved.
7.4.4
READY 2 state
READY 2 is the second UID resolving state where the NFC tag resolves the remaining 4
bytes of the 7 byte UID using the ANTICOLLISION or SELECT commands for cascade level
2.
READY 2 state is exited after the SELECT command from cascade level 2 with the matching
complete part of the UID has been executed. The NFC tag then proceeds into ACTIVE state
where the application-related commands can be executed.
7.4.5
ACTIVE state
ACTIVE state enables read and write accesses to unprotected memory.
If access to protected memory is required then the tag can transition from the ACTIVE state
to AUTHENTICATED state by executing the PWD_AUTH command in conjunction with the
correct 32 bit password.
