
GS9090A Preliminary Data Sheet
Proprietary and Confidential
34714 - 0
February 2006
50 of 69
The entire packet, including the ancillary data flag (ADF), data identification (DID),
secondary data identification (SDID), data count (DC), and checksum word will be
written into the memory. The device will detect ancillary data packet DID's placed
anywhere in the video data stream, including the active picture area.
Additionally, the lines from which the packets are to be extracted from can be
programmed into the ANC_LINE_A[10:0] and ANC_LINE_B[10:0] registers,
allowing ancillary data from a maximum of two lines per frame to be extracted. If
only one line number register is programmed (with the other set to zero), ancillary
data packets will be extracted from one line per frame only. When both registers
are set to zero, the device will extract packets from all lines.
The application layer reads the extracted ancillary data through the host interface
starting at address 02Ch up to 42Bh inclusive (1024 words). This must be done
while there is a valid video signal present at the serial input and the device is locked
(LOCKED = HIGH).
3.10.3.1 Ancillary Data Extraction and Reading
To start ancillary data extraction, the ANC_PKT_EXT bit of the IOPROC_DISABLE
register must be set HIGH (see
Table 3-14
in
Error Correction and Insertion on
page 42
). Packet extraction will begin in the following frame after this bit has been
set HIGH.
NOTE: Ancillary data extraction will not begin until 2200 PCLKs (82us) after the
device has entered into ancillary data extraction mode (FIFO_MODE[1:0] = 10b),
regardless of the setting of the ANC_PKT_EXT bit.
When the FIFO is configured for ancillary data extraction mode, setting the
IOPROC_EN pin LOW will disable packet extraction. If IOPROC_EN is LOW, the
setting of the ANC_PKT_EXT host interface bit will be ignored.
Clearing the ANC_PKT_EXT bit will not automatically disable ancillary data
extraction. To disable ancillary data extraction, switch the FIFO into bypass mode
by setting FIFO_MODE[1:0] = 11b. 2200 PCLK cycles after the device re-enters
ancillary data extraction mode, data extraction will commence immediately if
ANC_PKT_EXT is still HIGH.
The application layer can use the ANC_DETECT output flag available on the I/O
output pin (see
Programmable Multi-Function Outputs on page 55
) to determine
the length of the ancillary data extracted and when to begin reading the extracted
data from memory. Recall that ANC_DETECT is HIGH whenever ancillary data
has been detected.
In addition, the data count (DC) word, which is located three words after the
ancillary data flag (ADF) in the memory, can be read to determine how many valid
user data words (UDW) are present in the extracted packet (see SMPTE 291M for
more details). The DC value can then be used to preset how many address reads
must be performed to obtain only the user data words.