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NXP Semiconductors
PNX15xx/952x Series
Volume 1 of 1
Chapter 11: QVCP
PNX15XX_PNX952X_SER_N_4
NXP B.V. 2007. All rights reserved.
Product data sheet
Rev. 4.0 — 03 December 2007
11-368
The state change of the odd_even signal is always tied to the rising edge of the vsync
signal.
Figure 14 identies screen display parameters controlled by elds in the STG
registers
Other restrictions for the screen timing generation are as follows:
invalid HSYNCS/E settings: 0, 1, 2 > HTOTAL
invalid HBLNKS/E settings: 0, 1, > HTOTAL
invalid VSYNCS/E settings: 0, > VTOTAL
invalid VBLNKS/E settings: 0, > VTOTAL
invalid difference HSYNCE-HSYNCS: -1
invalid difference HBLNKE-HBLNKS: 0, -1, -2
In interlaced modes these differences are not allowed:1, 2, 3, 4 to guarantee
sufciently long horizontal blanking:
invalid difference VSYNCE-VSYNCS: -1
invalid difference VBLNKE-VBLNKS: 0, -1, -2
2.6 Mixer Structure
The properly formatted pixels from each layer are combined in a cascaded series of
mixer units. There is one mixer unit associated with each layer unit within the QVCP.
For a given screen position, each mixing unit can select the pixel from the layer, the
pixel from the previous mixer, or a blend of the two pixels. If a layer does not generate
a valid pixel for a specic screen position, then the mixer will pass the pixel from the
previous mixer. If no layers are producing valid pixels, a background color will be
displayed. The mixer selection criteria are based on a number of functions ROPs that
can be used to create such common effects as color keying. There are no restrictions
on window size, position, or overlap. A mode such as PIP is simple to implement by
setting layer_N for full screen video and layer_N+1 to the PIP. PIP size and position
may be changed on a frame by frame basis. Effects such as blending a PIP in and out
of the full screen video are easy to achieve using the 256 level alpha blend capability
of each mixer.
The main functionality of the mixer stages is to compose the outgoing pixel streams
from each layer to the nal display image. The mixer data path operates on 10 bits.
This includes clipping, alpha blending, inverting colors. Which of those functions is
applied and how, is dened in a set of raster operations (ROPs). A raster operation is
always a logical combination of several input keys and a specic ROP register which
enables one or more of the different key combinations. It (ROP operation) is like a
function that generates the output based on a logical combination of several input
signals and the programmable ROP register.
Each mixer knows 4 different keys (Key0, Key1, Key2, Key3) as illustrated in the mixer
block diagram.
– Key0, output key from previous layer, KeyPass ROP