MB87P2020 Datasheet, PDF (111/356 Pages) Fujitsu Component Limited. – Colour LCD/CRT/TV Controller

AAF Antialiasing Filter
1 Functional Description
The Anti Aliasing Filter (AAF) is a component of the Graphics Display Controller (GDC), which realizes
the anti aliasing filter function for some pixel commands. It is implemented in the GDC design between the
Pixel Processor (PP) and the SDRAM Controller (SDC), in reference to block diagram in GDC Specifica-
tion. The AAF processes data on the fly which should be stored in the Video RAM. Only for true or high
colour resolution pixel data an applicable result could be expected. Averaging of indexed colours may lead
to unexpected effects.
1.1 AAF Overview
1.1.1 Top Level Structure
Anti Aliasing Filter
SDC
SDC bus
SDC-Interface (SDC side)
AAF_EN
AAF control signals
Anti Aliasing Unit
CTRL-Interface
SDC-Interface (PP side)
control bus
SDC bus
ULB
Figure 1-1: AAF Block Diagram
Pixel Processor
all signals of SDC bus, such as
REQ, MCTRL, ADDR ...
AAF enable signal
register set data, such as THRESH-
OLD or OPTI_EN ...
The internal structure of AAF is shown in Figure 1-1. It consists of a bypass multiplexor, a control block,
the antialiasing unit (AAU) itself and two compatible interfaces to the SDC and PP modules.
The bypass is needed to switch the AAF in a transparent (disabled) mode. If AAU is disabled and the bypass
is active the clock supply of the whole AAF module can be switched off for power saving purposes. Addi-
tional if AAF is not used the SDRAM timing for read-to-write recovery can be made faster. The bypass
Functional Description
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