PCF8573 Ver la hoja de datos (PDF) - Philips Electronics
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PCF8573 Datasheet PDF : 28 Pages
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Philips Semiconductors
Clock/calendar with serial I/O
Product specification
PCF8573
8.3 System configuration
Refer to Fig.6. A device generating a message is a ‘transmitter’, a device receiving a message is the ‘receiver’. The
device that controls the message is the ‘master’ and the devices which are controlled by the master are the ‘slaves’.
SDA
SCL
MASTER
TRANSMITTER /
RECEIVER
SLAVE
RECEIVER
SLAVE
TRANSMITTER /
RECEIVER
MASTER
TRANSMITTER
MASTER
TRANSMITTER /
RECEIVER
MBA605
Fig.6 System configuration.
8.4 Acknowledge
See Fig.7. The number of data bytes transferred between
the start and stop conditions from transmitter to receiver is
unlimited. Each byte of eight bits is followed by an
acknowledge bit. The acknowledge bit is a HIGH level
signal put on the bus by the transmitter during which time
the master generates an extra acknowledge related clock
pulse. A slave receiver which is addressed must generate
an acknowledge after the reception of each byte. Also a
master receiver must generate an acknowledge after the
reception of each byte that has been clocked out of the
slave transmitter.
The device that acknowledges must pull down the SDA
line during the acknowledge clock pulse, so that the SDA
line is stable LOW during the HIGH period of the
acknowledge related clock pulse (set-up and hold times
must be taken into consideration). A master receiver must
signal an end of data to the transmitter by not generating
an acknowledge on the last byte that has been clocked
out of the slave. In this event the transmitter must leave the
data line HIGH to enable the master to generate a stop
condition, see Figs. 10 and 11.
handbook, full pagewidth
DATA OUTPUT
BY TRANSMITTER
DATA OUTPUT
BY RECEIVER
not acknowledge
acknowledge
SCL FROM
MASTER
1
2
S
START
condition
8
9
clock pulse for
acknowledgement
MBC602
Fig.7 Acknowledgment on the I2C-bus.
2003 Jan 27
8
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