GS1560A Gennum Corporation, GS1560A Datasheet - Page 34

• Manufacturer Part Number: GS1560A
• Description: Reclocking Deserializer For HD-SDI, Sd-sdi & Dvb-asi With Loop Thru Cable Driver. 3.3/1.8V Supply.
• Manufacturer: Gennum Corporation

3.8 DVB-ASI FUNCTIONALITY
3.8 DVB-ASI FUNCTIONALITY
3.8 DVB-ASI FUNCTIONALITY
3.8 DVB-ASI FUNCTIONALITY
The GS1560A is said to be in DVB-ASI mode once the
device has detected 32 consecutive DVB-ASI words without
a single word or disparity error being generated. The
device will remain in DVB-ASI mode until 32 consecutive
DVB-ASI word or disparity errors are detected, or until
SMPTE TRS ID words have been detected.
The lock detect block may also drop out of DVB-ASI mode
under the following conditions:
•
•
•
•
K28.5 sync patterns in the received DVB-ASI data stream
will be detected by the device in either inverted or non-
inverted form.
In master mode, the GS1560A sets the SMPTE_BYPASS pin
LOW and the DVB_ASI pin HIGH to indicate that it has
locked to a DVB-ASI input data stream. When operating in
slave mode, the application layer must set the SD/HD pin
HIGH, in addition to setting SMPTE_BYPASS LOW and
DVB_ASI HIGH, in order to enable DVB-ASI operation.
3.9 DATA THROUGH MODE
3.9 DATA THROUGH MODE
3.9 DATA THROUGH MODE
3.9 DATA THROUGH MODE
The GS1560A may be configured by the application layer to
operate as a simple serial-to-parallel converter. In this
mode, the device presents data to the output data bus
without performing any decoding, descrambling or word-
alignment.
Data
MASTER/SLAVE, SMPTE_BYPASS, and DVB_ASI input pins
are set LOW. Under these conditions, the lock detection
algorithm enters PLL lock mode, (see section 3.6.1), such
that the device may reclock data not conforming to SMPTE
or DVB-ASI streams.
When operating in master mode, the GS1560A will set the
SMPTE_BYPASS and DVB_ASI signals to logic LOW if
presented with a data stream without SMPTE TRS ID words
or DVB-ASI sync words. The LOCKED and data bus outputs
GENNUM CORPORATION
RESET_TRST is asserted LOW
CDx is HIGH
SMPTE_BYPASS is asserted HIGH in slave mode
DVB_ASI is asserted LOW in slave mode
through
SDO
SDO
mode
is
enabled
GS1560A
Fig. 9 DVB-ASI FIFO Implementation using the GS1560A
only
when
the
34 of 55
PCLK = 27MHz
AOUT ~ HOUT
WORDERR
SYNCOUT
8
3.8.1 DVB-ASI 8b/10b Decoding and Word Alignment
After serial-to-parallel conversion, the internal 10-bit data
bus is fed to the DVB-ASI 8b/10b decode and word
alignment block. The function of this block is to word align
the data to the K28.5 sync characters, and 8b/10b decode
and bit-swap the data to achieve bit alignment with the data
outputs.
The extracted 8-bit data will be presented to DOUT[17:10],
bypassing all internal SMPTE mode data processing.
3.8.2 Status Signal Outputs
In DVB-ASI mode, the DOUT19 and DOUT18 pins will be
configured as DVB-ASI status signals SYNCOUT and
WORDERR respectively.
SYNCOUT will be HIGH whenever a K28.5 sync character
is present on the output. This output may be used to drive
the write enable signal of an external FIFO, thus providing a
means of removing the K28.5 sync characters from the data
stream. Parallel DVB-ASI data may then be clocked out of
the FIFO at some rate less than 27MHz. See Figure 9.
WORDERR will be high whenever the device has detected
a running disparity error or illegal code word.
will be forced LOW and the serial digital loop-through
output will be a buffered version of the input.
3.10 ADDITIONAL PROCESSING FUNCTIONS
3.10 ADDITIONAL PROCESSING FUNCTIONS
3.10 ADDITIONAL PROCESSING FUNCTIONS
3.10 ADDITIONAL PROCESSING FUNCTIONS
The GS1560A contains an additional data processing block
which is available in SMPTE mode only, (see section 3.7).
3.10.1 FIFO Load Pulse
To aid in the application-specific implementation of auto-
phasing and line synchronization functions, the GS1560A
will generate a FIFO load pulse to reset line-based FIFO
storage.
The FIFO_LD output pin will normally be HIGH but will go
LOW for one PCLK period, thereby generating a FIFO write
reset signal.
CLK_IN
WE
FIFO
CLK_OUT
8
READ_CLK
>27MHz
TS
FE
FF
WORDERR
27360-1