Philips Semiconductors
Product specification
Low power clock/calendar
PCF8593
9
I2C-BUS PROTOCOL
Addressing
9.1
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 clock/calendar 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 clock/calendar slave address is shown in Fig.17.
handbook, halfpage
1
0
1
0
0
0
1 R/W
MBD821
group 2
group 1
Fig.17 Slave address.
9.2
Clock/calendar READ/WRITE cycles
The I2C-bus configuration for the different PCF8593 READ and WRITE cycles is shown in Figs 18, 19 and 20.
acknowledgement
from slave
acknowledgement
from slave
acknowledgement
from slave
handbook, full pagewidth
S
SLAVE ADDRESS
0
A
WORD ADDRESS
A
DATA
A
P
R/W
n bytes
auto increment
memory word address
MBD822
Fig.18 Master transmits to slave receiver (WRITE) mode.
1997 Mar 25
17
NXP [ NXP ]
