Datasheet

ADV7188
Rev. A | Page 29 of 112
SD_OFF_CB [7:0], SD Offset Cb Channel,
Address 0xE1 [7:0]
These bits allow the user to adjust the hue of the picture by
selecting the offset for the Cb channel. There is a functional
overlap with the HUE [7:0] bits.
Table 31. SD_OFF_CB [7:0] Function
SD_OFF_CB [7:0] Description
0x80 (default) 0 mV offset applied to the Cb channel
0x00 −568 mV offset applied to the Cb channel
0xFF +568 mV offset applied to the Cb channel
SD_OFF_CR [7:0], SD Offset Cr Channel, Address 0xE2 [7:0]
These bits allow the user to select an offset for data on only the
Cr channel and to adjust the hue of the picture. There is a
functional overlap with the HUE [7:0] bits.
Table 32. SD_OFF_CR [7:0] Function
SD_OFF_CR [7:0] Description
0x80 (default) 0 mV offset applied to the Cr channel
0x00 −568 mV offset applied to the Cr channel
0xFF +568 mV offset applied to the Cr channel
BRI [7:0], Brightness Adjust, Address 0x0A [7:0]
These bits control the brightness of the video signal and allow
the user to adjust the brightness of the picture.
Table 33. BRI [7:0] Function
BRI [7:0] Description
0x00 (default) Offset of the luma channel = 0 mV
0x7F Offset of the luma channel = +204 mV
0x80 Offset of the luma channel = −204 mV
HUE [7:0], Hue Adjust, Address 0x0B [7:0]
These bits contain the value for the color hue adjustment and
allow the user to adjust the hue of the picture.
HUE [7:0] has a range of ±90°, with a value of 0x00 equivalent to
an adjustment of 0°. The resolution of HUE [7:0] for one bit is 0.7°.
The hue adjustment value is fed into the AM color demodulation
block. Therefore, it only applies to video signals that contain
chroma information in the form of an AM-modulated carrier
(CVBS or Y/C in PAL or NTSC). It does not affect SECAM and
does not work on component video inputs (YPrPb).
Table 34. HUE [7:0] Function
HUE [7:0] Description
0x00 (default) Phase of the chroma signal = 0°
0x7F Phase of the chroma signal = +90°
0x80 Phase of the chroma signal = −90°
DEF_Y [5:0], Default Value Y, Address 0x0C [7:2]
If the ADV7188 loses lock to the incoming video signal or if
there is no input signal, the DEF_Y [5:0] bits allow the user to
specify a default luma value to be output. The register is used if
• The DEF_VAL_AUTO_EN bit is set high and the ADV7188
loses lock to the input video signal. This is the intended
mode of operation (automatic mode).
• The DEF_VAL_EN bit is set regardless of the lock status of
the video decoder. This is a forced mode that may be useful
during configuration.
The DEF_Y [5:0] values define the six MSBs of the output video.
The remaining LSBs are padded with 0s. For example, in 10-bit
mode, the output is Y [9:0] = {DEF_Y [5:0], 0, 0, 0, 0}.
The value for Y is set by the DEF_Y [5:0] bits. A value of 0x0D
in conjunction with the DEF_C [7:0] default setting produces a
blue color.
Register 0x0C has a default value of 0x36.
DEF_C [7:0], Default Value C, Address 0x0D [7:0]
The DEF_C [7:0] bits complement the DEF_Y [5:0] bits. These
bits define the four MSBs of the Cr and Cb values to be output if
• The DEF_VAL_AUTO_EN bit is set high and the ADV7188
cannot lock to the input video (automatic mode).
• The DEF_VAL_EN bit is set high (forced output).
The data that is finally output from the ADV7188 for the chroma
side is the output pixel buses Cr [7:0] = {DEF_C [7:4], 0, 0, 0, 0}
and Cb [7:0] = {DEF_C [3:0], 0, 0, 0, 0}.
In full 12-bit output mode, two extra LSBs of value 00 are appended.
The values for Cr and Cb are set by the DEF_C [7:0] bits. A
value of 0x7C in conjunction with the DEF_Y [5:0] default
setting produces a blue color.
DEF_VAL_EN, Default Value Enable, Address 0x0C [0]
This bit forces the use of the default values for Y, Cr, and Cb.
Refer to the descriptions in the
DEF_Y [5:0], Default Value Y,
Address 0x0C [7:2]
and DEF_C [7:0], Default Value C, Address
0x0D [7:0]
sections for additional information. In this mode,
the decoder also outputs a stable 27 MHz clock, HS, and VS.
0 (default)—Outputs a colored screen determined by user-
programmable Y, Cr, and Cb values when the decoder free runs.
Free-run mode is turned on and off via DEF_VAL_AUTO_EN.
1—Forces a colored screen output determined by user-
programmable Y, Cr, and Cb values. This overrides picture
data even if the decoder is locked.