VSP 94x2A
DATA SHEET
2.2.6. Contrast, Brightness and Saturation Control
of Input Signal
k = MIXGAIN ⋅ (31 – FBLOFFST) + 32
The YUV signal can be manipulated in order to fit to
the main channel. The contrast can be adjusted
between 0 and 1.97 in 64 steps (CONADJ). The
brightness is adjustable in 255 steps (BRTADJ). Due
to the independent chroma adjustment of U and V (64
steps each, USATADJ, VSATADJ), UV as well as
CrCb input signals can both be displayed correctly.
All necessary limitation and rounding operations are
built-in to fit the range: 0 ≤ k ≤ 128
Considering MIXGAIN=3, k is obtained by
k = 158 – 3 ⋅ FBLOFFST
[κ limited to 0 and 128]
2.2.7. Soft Mix
The soft-mixer circuit consists of a Fast Blank (FB)
processing block supplying a mixing factor k (0... 128)
achieving the output function:
The mixing is only controlled by FBLOFFST.
In the static mixer mode as well as in the previously
mentioned static switch mode, the softmixer operates
independently of the analog fast blank input.
YUVmain ⋅ (128 – k) + YUVinserted ⋅ k
YUVmix= --------------------------------------------------------------------------------------------
128
2.2.10. Dynamic Mixer mode
In the dynamic mixer mode, the mixer is controlled by
the Fast Blank signal. The VSPA provides a linear mix-
ing coefficient
k= ‘0’ means that only the main signal is fed through to
the output. k= ‘128’ means that only the inserted signal
becomes visible. The soft mixer supports four modes
that are selected by MIXOP and SMOP.
MIXGAIN(FB – FBLOFFST ⋅ 2)
Table 2–7: RGB operation modes
k = ----------------------------------------------------------------------------------- + 64
2
MIXOP
SMOP
Soft Mix mode
The dynamic mode is used for mixing which is depen-
dent on FB input. FB is the preprocessed digitized fast-
blank input in the range from 0...127. FBL manipulation
is done both for luminance and chrominance FBL sig-
nal.
00
0
Dynamic Soft Mix
(DECTWO must be set to ’1’)
00
1
Static Soft Mix
(DECTWO must be set to ’1’)
Fast blank is delay adjustable by FBLDEL in the range
of -2...4 clock cycles.
01
10
11
x
x
x
Only RGB/YUV path visible
Only CVBS path visible
(Reserved)
2.2.11. FBL Activity and Overflow Detection
It is important to know whether the FBL input is used
or not. Therefore a detection circuit gives information
via the I C bus to the microcontroller. The circuit uses
2.2.8. Static Switch mode
2
the FBL value as input. If it is greater than a threshold
for one or five clock cycles (FBLCONF), the I C regis-
ter FBLACTIVE is set. This register is reset after a
read access by the microcontroller. PFBL, PG, PR, PB
indicate an overflow of the corresponding ADC (upper
limit: ADC= 255) exceeding 5 clock cycles duration.
In its simplest and most common application the soft-
mixer is used as a static switch between YUVmain and
YUVinsert. This for instance the adequate way to han-
dle a DVD component signal. By using MIXOP, k is
internally set to 0 or 128 respectively.
2
2.2.9. Static Mixer mode
The signal YUVmain and the component signal YUVin-
sert may also be statically mixed. In this environment,
k is manually controlled via FBLOFFSET and MIX-
GAIN.
16
Aug. 16, 2004; 6251-552-1DS
Micronas
MICRONAS [ MICRONAS ]
