Datasheet

PN512 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2016. All rights reserved.
Product data sheet
COMPANY PUBLIC
Rev. 5.2 — 16 June 2016
111352 77 of 137
NXP Semiconductors
PN512
Full NFC Forum-compliant frontend
9.4.4 Acknowledge
An acknowledge must be sent at the end of one data byte. The acknowledge-related clock
pulse is generated by the master. The transmitter of data, either master or slave, releases
the SDA line (HIGH) during the acknowledge clock pulse. The receiver pulls down the
SDA line during the acknowledge clock pulse so that it remains stable LOW during the
HIGH period of this clock pulse.
The master can then generate either a STOP (P) condition to stop the transfer or a
repeated START (Sr) condition to start a new transfer.
A master-receiver indicates the end of data to the slave-transmitter by not generating an
acknowledge on the last byte that was clocked out by the slave. The slave-transmitter
releases the data line to allow the master to generate a STOP (P) or repeated START (Sr)
condition.
Fig 20. Acknowledge on the I
2
C-bus
mbc602
S
START
condition
9821
clock pulse for
acknowledgement
not acknowledge
acknowledge
data output
by transmitter
data output
by receiver
SCL from
master
Fig 21. Data transfer on the I
2
C-bus
msc608
Sr
or
P
SDA
Sr
P
SCL
STOP or
repeated START
condition
S
or
Sr
START or
repeated START
condition
1 2 3 - 8 9
ACK
9
ACK
7812
MSB
acknowledgement
signal from slave
byte complete,
interrupt within slave
clock line held LOW while
interrupts are serviced
acknowledgement
signal from receiver