PCD4440T Ver la hoja de datos (PDF) - Philips Electronics
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PCD4440T Datasheet PDF : 20 Pages
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Philips Semiconductors
Analog voice scrambler/descrambler
Product specification
PCD4440T
8.3 System configuration (see Fig.8)
A device generating a message is a ‘transmitter’, a device receiving a message is the ‘receiver’. The device that controls
message transfer is the ‘master’ and the devices that are controlled by the master are the ‘slaves’.
SDA
SCL
MASTER
TRANSMITTER /
RECEIVER
SLAVE
RECEIVER
SLAVE
TRANSMITTER /
RECEIVER
MASTER
TRANSMITTER
Fig.8 System configuration.
MASTER
TRANSMITTER /
RECEIVER
MBA605
8.4 Acknowledge (see Fig.9)
The number of data bytes transferred between the start and stop conditions from transmitter to receiver is not limited.
Each byte of eight bits is followed by one acknowledge bit. The acknowledge bit is a HIGH level put on the bus by the
transmitter whereas the master generates an extra acknowledge after the reception of each byte. Also a master must
generate an acknowledge after reception of each byte that has been clocked out of the slave transmitter. The device that
acknowledges has to pull down the SDA line during the acknowledge-related clock pulse. Set-up and hold times must
be taken into account to ensure that the SDA line is stable LOW during the whole high period of the acknowledge-related
clock pulse. 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 the stop condition.
DATA OUTPUT
BY TRANSMITTER
DATA OUTPUT
BY RECEIVER
not acknowledge
acknowledge
SCL FROM
MASTER
1
2
8
S
START
CONDITION
MBC602
Fig.9 Acknowledgment on the I2C-bus.
9
clock pulse for
acknowledgement
1996 Dec 20
10
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