NT3H2111 Datasheet, PDF (57/77 Pages) NXP Semiconductors – Designed to be the perfect enabler for NFC in home-automation

NXP Semiconductors
NT3H2111/NT3H2211
NFC Forum Type 2 Tag compliant IC with I²C interface
11. Communication and arbitration between NFC and I²C interface
If both interfaces are powered by their corresponding source, only one interface shall
have access to the memory according to the "first-come, first-serve" principle.
In NS_REG, the two status bits I2C_LOCKED and RF_LOCKED reflect the status of the
NTAG I²C plus memory access and indicate which interface is locking the memory
access. At power-on, both bits are 0, setting the arbitration in idle mode.
In the case arbiter locks to the I²C interface, an NFC device still can read the session
registers. If the NFC state machine is in ACTIVE state, only the SECTOR SELECT
command is allowed. But any other command requiring EEPROM access like READ or
WRITE is handled as an illegal command and replied to with a special NAK value.
In the case where the memory access is locked to the NFC interface, the I²C host still can
access the session register, by issuing a 'Register READ/WRITE' command. All other
read or write commands will be replied to with a NACK to the I²C host.
11.1 Pass-through mode not activated
PTHRU_ON_OFF = 0b (see Table 14) indicates non-pass-through mode.
11.1.1 I²C interface access
If the tag is in the IDLE or HALT state (NFC state after POR or HALT-command) and the
correct I²C slave address of NTAG I²C plus is received following the START condition, the
bit I2C_LOCKED will be automatically set to 1b. If I2C_LOCKED = 1b, the I²C interface
has access to the tag memory and the tag will respond with a NACK to any memory
READ/WRITE command on the NFC interface other than reading the session register
bytes command during this time.
I2C_LOCKED must be either reset to 0b at the end of the I²C sequence or will be cleared
automatically after the end of the watch dog timer.
11.1.2 NFC interface access
The arbitration will allow the NFC interface read and write accesses to EEPROM only
when I2C_LOCKED is set to 0b.
RF_LOCKED is automatically set to 1b if the tag receives a valid command (EEPROM
Access Commands) on the NFC interface. If RF_LOCKED = 1b, the tag is locked to the
NFC interface and will not respond to any command from the I²C interface other than
READ register command (see Table 14).
RF_LOCKED is automatically set to 0b in one of the following conditions
• At POR or if the NFC field is switched off
• If the tag is set to the HALT state with a HALT command on the NFC interface
• If the memory access command is finished on the NFC interface
When the NFC interface has read the last page of the NDEF message specified in
LAST_NDEF_BLOCK (see Table 13 and Table 14) the bit NDEF_DATA_READ - in the
register NS_REG see Table 14 - is set to 1b and indicates to the I²C interface that, for
example, new NDEF data can be written.
NT3H2111/NT3H2211
Product data sheet
COMPANY PUBLIC
All information provided in this document is subject to legal disclaimers.
Rev. 3.0 — 3 February 2016
359930
© NXP Semiconductors N.V. 2016. All rights reserved.
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