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written approval of the Semiconductor Group of Siemens AG.
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2
in the I
Semiconductor Group302.97
C system provided the system conforms to the I2C specifications defined by Philips.
VPS / PDC-plus Decoder SDA 5650/X
CMOS
1General Description
The PDC plus SDA 5650 decoder chip receives all
VPS and 8/30 Format 1 and 2 data together with the
teletext header information for easy identification of
broadcast transmitter. The SDA 5650 includes a
storage capacity of 16 bytes which can be used in
different ways depending on selected modes.
P-DIP-14-1
1.1Features
• Single chip receiver for PDC data for
Broadcast Data Service Packet (BDSP 8/30/2
according to CCIR teletext system B.)
VPS Data in dedicated line no. 16 of the vertical
blanking interval (VBI)
• Reception of BDSP packet 8/30/1
Unified Date and Time (UDT)
Network indentification code (NIC)
Short program label (SPL)
• Reception of teletext header row
Bytes no. 14 - 45 containing date, clock time and identification
• On chip data slicer
• Low external component count
2
• I
C-Bus interface
Communication with external microcontroller
• PDC/VPS operation mode selectable via I
2
C-Bus register
• Pin and software compatible to PDC/VPS decoder SDA 5649
Ground (0 V)
Analog ground (0 V)
Digital ground (0 V)
3, 8, 13, 18 N.C.Not connected
24SCLSerial clock input of I
35SDASerial data input of I
46CS0Chip select input determining the I
20
/ 21H, when pulled low
H
22
/ 23H, when pulled high.
H
2
C Bus.
2
C Bus.
2
C-Bus addresses:
57VCSVideo Composite Sync output from sync slicer used for
PLL based clock generation.
69DAVNData available output active low, when VPS data is
received.
710EHBOutput signaling the presence of the first field active
high.
811TITest input; activates test mode when pulled high.
Connect to ground for operating mode.
912PD1Phase detector/charge pump output of data PLL
(DAPLL).
1014PD2/
Connector of the loop filter for the SYSPLL.
VCO2
1115VCO1Input to the voltage controlled oscillator #1 of the
DAPLL.
1216
I
REF
Reference current input for the on-chip analog circuit.
1317CVBSComposite video signal input.
14
19
V
V
DD
DDD
Positive supply voltage (+ 5 V nom.).
Positive supply voltage for the digital circuits
(+ 5 V nom.).
20
V
DDA
Positive supply voltage for the analog circuits
(+ 5 V nom.).
Semiconductor Group602.97
Block Diagram
SDA 5650/X
Figure 2
Semiconductor Group702.97
SDA 5650/X
2System Description
2.1Functions
Referring to the functional block diagram of the PDC / VPS decoder, the composite video
signal with negative going sync pulses is coupled to the pin CVBS through a capacitor
which is used for clamping the bottom of the sync pulses to an internally fixed level. The
signal is passed on to the slicer, an analogue circuitry separating the sync and the data
parts of the CVBS signal, thus yielding the digital composite sync signal VCS and a
digital data signal for further processing by comparing those signals to internally
generated slicing levels.
The output of the sync separator is forwarded, on one hand, to the output pin VCS, and
on the other hand, to the clock generator and the timing block. The VCS signal
represents a key signal that is used for deriving a system clock signal by means of a PLL
and all other timing signal.
The data slicer separates the data signal from the CVBS signal by comparing the video
voltage to an internally generated slicing level which is found by averaging the data
signal during TV line no. 16 in the VPS mode or by averaging the data signal during the
clock run-in period of the teletext lines during the data entry window (DEW) in PDC
mode.
The clock generator delivers the system clock needed for the basic timing as well as for
the regeneraton of the dataclock. It is based on two phase locked loops (PLL’s) all parts
of which are integrated on chip with the exception of the loop filter components. Each of
the PLL’s is composed of a voltage controlled relaxation oscillator (VCO), a phase/
frequency detector (PFD), and a charge pump which converts the digital output signals
of the PFD to an analogue current. That current is transformed to a control voltage for
the VCO by the off-chip loop filter. The generated VCO frequencies are 10 MHz and
13.875 MHz for VPS mode and PDC mode, respectively.
All signals necessary for the control of sync and data slicing as well as for the data
acquisition are generated by the Timing block.
The SDA 5650 can be operated in three different modes: Depending on the selected
operating mode, either teletext lines carrying 8/30 packages, the dedicated TV line
no. 16 (VPS) or the teletext header bytes 38-45, 30-37, 22-29 and 14-21 are acquired.
In PDC mode, only teletext rows 8/30 containing Broadcast Data Service Package
(BDSP) information are acquired. The relevant bytes of 8/30 format 1 (8/30/1) and 8/30
format 2 (8/30/2) are extracted. The 8/30/1-bytes are stored in the acquisition register in
a transparent way without any bit manipulation, whereas the Hamming coded bytes of
packet 8/30/2 are Hamming-checked and bytes with one bit error are corrected. The
storage of error free or corrected 8/30/2-data bytes in the transfer register to the I
2
C Bus
is signalled by the DAVN output going low.
Semiconductor Group802.97
SDA 5650/X
In VPS mode, the extracted data bits of TV line no. 16 are checked for biphase errors.
With no biphase errors encountered, the acquired bytes are stored in the transfer
register to the I
as well.
In TTX header mode A bytes 38-45 and 30-37 are accessed in this order. This assures
software compatibility to the SDA 5649. In mode B bytes 22-29 and 14-21 are accessed
in this order.
In all three operating modes data are updated when a new data line has been received,
provided that the chip is not accessed via the I2C Bus at the same time.
A micro controller can read the stored bytes via the I
However, one must be aware that the storage of new data from the acquisition interface
is inhibited as long as the PDC decoder is being accessed via the I
Note: In order to achieve maximum system performance it is recommended to start the
SDA 5650 in VPS mode (state after power on) and read the register to check
whether line 16 is received. After reception of VPS data inline 16 the SDA 5650
can be switched to 8/30 mode and waiting for packet 8/30 data. Since VPS data
in line 16 is transmitted every frame and PDC data in packet 8/30 is transmitted
nearly every second the recognition of both VPS and 8/30 packets can be done
within PDC-system constraints (about 1 sec).
2
C Bus. That transfer is signalled by a H/L transition of the DAVN output,
2
C-Bus interface at any time.
2
C Bus.
2.2I
2
C Bus
2.2.1General Information
2
The I
C-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 I
2
C 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:Start Condition generated by master
AS:Acknowledge by slave
AM:Acknowledge by master
NAM:No Acknowledge by master
STOP:Stop condition generated by master
Semiconductor Group902.97
SDA 5650/X
2.2.2Chip Address
There are two pairs of chip addresses, which are selected by the CS0-input pin
according to the following table:
CS0 InputWrite ModeRead Mode
Low20 (hex)21 (hex)
High22 (hex)23 (hex)
2.2.3Write Mode
For writing to the PDC decoder, the following format has to be used:
Start Chipaddress and Write ModeASByte to set Control RegisterASStop
Description of 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.
2
The write mode is used to set the I
C-Bus control register which determines the
operating mode:
Semiconductor Group1002.97
SDA 5650/X
Control Register:
Bit Number:76543210
T4T3T2T1MABHDTPDC/
VPS
FOR1/
FOR2
Default: All bits are set to 0 on power-up.
Bits 4 through 7 are used for test purposes and must not be changed for normal
operation by user software!
2
Bit 0:determines, which kind of data is accessed via the I
C Bus when PDC
mode is active:
Value
01
BDSP 8/ 30/ 2 data accessibleBDSP 8/ 30/ 1 or header row
data accessible (refer to description of
Bit 2)
Bit 1:determines the operating mode:
Value
01
VPS mode activePDC mode active
Bit 2:determines whether BDSP 8/30/1-data or header row data is
accessible:
Value
01
BDSP 8/30/1 data accessibleBytes of teletext header in mode A or B
(see Bit 3)
Bit 3:determines mode of teletext header access:
Value
01
Mode A: header bytes in order 38-45,
30-37
Mode B: header bytes in order 22-29,
14-21
Semiconductor Group1102.97
SDA 5650/X
2.2.4Read Mode
For reading from the PDC decoder, the following format has to be used
StartChipaddress Read Mode AS1st ByteAM..... Last ByteNAMStop
The contents of up to 16 registers (bytes) can be read starting with byte 1 bit 7 (refer to
the table Order of Data Output on the I
operating mode.
Description of Data Transfer (Read Mode)
Step1: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. The byte address
counter in the decoder is reset and points to the first byte to be output.
Step 2:The bus master puts the chip address on the SDA line during the next eight
SCL pulses.
2
C Bus and...) depending on the selected
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. At
this moment, the slave switches to transmitting mode.
Step 4:During the next eight clock pulses the slave puts the addressed data byte
onto the SDA line.
Step 5:The reception of the byte is acknowledged by the master device which, in
turn, pulls down the SDA line during the next SCL clock pulse. By
acknowledging a byte, the master prompts the slave to increment its internal
address counter and to provide the output of the next data byte.
Step 6:Steps no. 4 and no. 5 are repeated, until the desired amount of bytes have
been read.
Step 7:The last byte is output by the slave since it will not be acknowledged by the
master.
Step 8:To conclude the read operation, the master doesn’t acknowledge the last byte
to be received. A No Acknowledge by the master (NAM) causes the slave to
switch from transmitting to receiving mode. Note that the master can
prematurely cease any reading operation by not acknowledging a byte.
Step 9:The master gains control over the SDA line and concludes the data transfer
by generating a Stop Condition on the bus, i. e., by producing a low/high
transition on the SDA line while the SCL line is in a high state. With the SDA
2
and the SCL lines being both in a high state, the I
C Bus is free and ready for
another data transfer to be started.
Semiconductor Group1202.97
SDA 5650/X
2.3Order of Data Output on the I2C Bus and Bit Allocation of PDC/VPS
Operating Modes
2
I
C BusPDC Packet 8/30VPS Mode
Format 1Format 2
Byte 1bit 7
t
byte 15bit 0
6
5
4
3
2
1
0
2)
byte 16bit 0
1
2
3
4
byte 17bit 0
5
6
7
1)
byte 11bit 0
1
2
3
2)
1
2
3
4
1
2
3
5
6
7
Byte 2bit 7
Byte 3bit 7
Byte 4bit 7
byte 16bit 0
6
5
4
3
2
1
0
1
2
3
4
5
6
7
byte 17bit 0
6
5
4
3
2
1
0
1
2
3
4
5
6
7
byte 18bit 0
6
5
4
3
2
1
0
1
2
3
4
5
6
7
byte 18bit 0
1
2
3
byte 19bit 0
1
2
3
byte 20bit 0
1
2
3
byte 21bit 0
1
2
3
byte 22bit 0
1
2
3
byte 23bit 0
1
2
3
byte 12bit 0
1
2
3
4
5
6
7
byte 13bit 0
1
2
3
4
5
6
7
byte 14bit 0
1
2
3
4
5
6
7
1)
Message bit numbers according to EBU specification of PDC system.
2)
Transmission bit number.
Semiconductor Group1302.97
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