PCF8563T datasheet(15/30 Pages) PHILIPS

15 / 30 page

Philips Semiconductors

PCF8563

Real-time clock/calendar

Product speciﬁcation

16 April 1999

15 of 30

9397 750 04855

8.9.5

I2C-bus protocol

Addressing: Before any data is transmitted on the I2C-bus, the device which should

respond is addressed ﬁrst. The addressing is always carried out with the ﬁrst byte

transmitted after the start procedure.

The PCF8563 acts as a slave receiver or slave transmitter. Therefore the clock signal

SCL is only an input signal, but the data signal SDA is a bidirectional line.

The PCF8563 slave address is shown in Figure 10.

Clock/calendar read/write cycles: The I2C-bus conﬁguration for the different

PCF8563 read and write cycles are shown in Figure 11, 12 and 13. The word

address is a four bit value that deﬁnes which register is to be accessed next. The

upper four bits of the word address are not used.

Fig 10. Slave address.

Fig 11. Master transmits to slave receiver (write mode).

handbook, halfpage

MRB016

A0 R/W

group 1

group 2

width

SLAVE ADDRESS

WORD ADDRESS

DATA

acknowledgement

from slave

acknowledgement

from slave

acknowledgement

from slave

R/W

auto increment

memory word address

MBD822

n bytes

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