SDA5649 Datasheet, PDF (6/26 Pages) Siemens Semiconductor Group – Expanded Decoder for Program Delivery Control and Video Program System EPDC / VPS Decoder

SDA 5649
SDA 5649X
I²C-Bus
General Information
The I²C-Bus interface implemented on the PDC decoder is a slave transmitter/receiver, i.e., both
reading from and writing to the PDC / VPS decoder is possible. The clock line SCL is controlled only
by the bus master usually being a micro controller, whereas the SDA line is controlled either by the
master or by the slave. A data transfer can only be initiated by the bus master when the bus is free,
i.e., both SDA and SCL lines are in a high state. As a general rule for the I²C-Bus, the SDA line
changes state only when the SCL line is low. The only exception to that rule are the Start Condition
and the Stop Condition. Further Details are given below. The following abbreviations are used:
START :
AS :
AM :
NAM :
STOP :
Start Condition generated by master
Ackknowledge by slave
Ackknowledge by master
No Ackknowledge by master
Stop Condition generated by master
Chip Address
There are two pairs of chip addresses, which are selected by the CS0-input pin according to the
following table:
CS0 Input
Low
High
Write Mode
20 (hex)
22 (hex)
Read Mode
21 (hex)
23 (hex)
Write Mode
For writing to the PDC decoder, the following format has to be used.
START Chipadress Write Mode
AS Byte Set Control Register AS STOP
Data Transfer (Write Mode)
Step1: In order to start a data transfer the master generates a Start Condition on the bus by pulling
the SDA line low while the SCL line is held high.
Step 2: The bus master puts the chip address on the SDA line during the next eight SCL pulses.
Step 3: The master releases the SDA line during the ninth clock pulse. Thus the slave can generate
an acknowledge (AS) by pulling the SDA line to a low level.
Step 4: The controller transmits the data byte to set the Control register.
Step 5: The slave acknowledges the reception of the byte.
Step 6: The master concludes the data communication by generating a Stop Condition.
The write mode is used to set the I²C-Bus control register which determines the operating mode:
Semiconductor Group
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