adv7188 Analog Devices, Inc., adv7188 Datasheet - Page 65

• Manufacturer Part Number: adv7188
• Description: Multiformat Sdtv Video Decoder With Fast Switch Overlay Support
• Manufacturer: Analog Devices, Inc.

CGMS and WSS
The CGMS and WSS data packets convey the same type of
information for different video standards. WSS is for PAL and
CGMS is for NTSC; therefore, the CGMS and WSS readback
registers are shared. WSS is biphase coded, and the VDP performs
a biphase decoding to produce the 14 raw WSS bits in the CGMS/
WSS readback I
CGMS_WSS_CLEAR, CGMS/WSS Clear, Address 0x78 [2],
User Sub Map, Write Only, Self-Clearing
1—Reinitializes the CGMS/WSS readback registers.
CGMS_WSS_AVL CGMS/WSS, Available Bit,
Address 0x78 [2], User Sub Map, Read Only
0—CGMS/WSS was not detected.
1—CGMS/WSS was detected.
CGMS_WSS_DATA_0 [3:0], Address 0x7D [3:0]
CGMS_WSS_DATA_1 [7:0], Address 0x7E [7:0]
CGMS_WSS_DATA_2 [7:0], Address 0x7F [7:0]
These read-only bits, located in the user sub map, hold the
decoded CGMS or WSS data.
Refer to Figure 39 and Figure 40 for the I
bit mapping.
2
C registers and to set the CGMS_WSS_AVL bit.
2
C to WSS and CGMS
Rev. A | Page 65 of 112
CC
Two bytes of decoded closed caption data are available in the
I
be obtained from the CC_EVEN_FIELD bit (Register 0x78).
CC_CLEAR, Closed Captioning Clear, Address 0x78 [0],
User Sub Map, Write Only, Self-Clearing
1—Reinitializes the CC readback registers.
CC_AVL, Closed Captioning Available, Address 0x78 [0],
User Sub Map, Read Only
0—Closed captioning was not detected.
1—Closed captioning was detected.
CC_EVEN_FIELD, Address 0x78 [1], User Sub Map,
Read Only
Identifies the field from which the CC data was decoded.
0—Closed captioning was detected on an odd field.
1—Closed captioning was detected on an even field.
VDP_CCAP_DATA_0, Address 0x79 [7:0], User Sub Map,
Read Only
Decoded Byte 1 of CC data.
VDP_CCAP_DATA_1, Address 0x7A [7:0], User Sub Map,
Read Only
Decoded Byte 2 of CC data.
2
C registers. The field information of the decoded CC data can
ADV7188