GS2971A Datasheet, PDF (77/152 Pages) Gennum Corporation – Integrated audio clock generator

To start Ancillary Data Extraction, the ANC_DATA_EXT_MASK bit of the host interface
must be set LOW. Ancillary data packet extraction begins in the following frame (see
Figure 4-32: Ancillary Data Extraction - Step A).
Application Layer
Read Pointer
Internal Write
Pointer
Bank A
0 ANCDATA
ANC DATA
ANC DATA
ANC DATA
ANC DATA
ANC DATA
ANC DATA
800h
Bank B
0
800h
1023
BFFh
1023
BFFh
ANC_DATA_SWITCH = LOW
Figure 4-32:Ancillary Data Extraction - Step A
Ancillary data is written into Bank A until full. The Y/1ANC and C/2ANC output flags
can be used to determine the length of the ancillary data extracted and when to begin
reading the extracted data from memory.
While the ANC_DATA_EXT_MASK bit is set LOW, the ANC_DATA_SWITCH bit can be
set HIGH during or after reading the extracted data. New data is then written into Bank
B (up to 1024 x 16-bit words), using the corresponding host interface addresses (see
Figure 4-33: Ancillary Data Extraction - Step B).
GS2971A 3Gb/s, HD, SD SDI Receiver
Data Sheet
54311 - 2
September 2012
77 of 152