NEC startWARE-GHS-Ravin-E, User Manual

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17 User’s Manual U17316EE1V0UM00
Chapter 3 Functional Description
Ravin-E (µPD72255Y) is the successor of the Ravin (µPD72254Y) display controller, designed for use
in car navigation, multimedia and passenger entertainment systems. In addition to the original display
control and drawing functions of µPD72254Y, Ravin-E supports high quality alpha blending for all win-
dow layers. This alpha blending feature is also employed for anti-aliased line drawing. Ravin-E also pro-
vides a function for capturing and displaying external video signals as well as a built-in D/A converter for
analogue CRT or TFT displays. Ravin-E can be connected to virtually any 32-bit host CPU with an
asynchronous SRAM-like bus interface. A second 32-bit wide data bus connects to standard SDRAMs
which serve as the frame buffer for the graphics and the video.
Figure 3-1: startWARE-GHS-Ravin-E Block Diagram
As shown in the above block diagram, Ravin-E connects through a 96-pin DIN connector to the host
CPU platform. This platform will be typically equipped with a V
R
41xx MIPS-RISC CPU, but it may be
adapted to any other CPU with a suitable SRAM-like interface. The signal levels are 3.3 V LVTTL and
the pinout is defined in “Host Connector CN1” on page 24 of the appendix.
Ravin-E is connected to two 256 Mbit SDRAMs, each one of them being 16-bit wide. These SDRAMs
are primarily employed as frame buffer for the graphics, as video buffer for the overlaid video and also
to store bitmaps, which can then be transferred quickly to the active screen location. The SDRAM also
holds the alpha values when alpha blending is used and the z-values in case of 3-D applications. Even
though the interface is not bandwidth optimized, the CPU has direct access to all locations in the
SDRAM and therefore it might make use of any otherwise unused memory locations.
The SAA7113H or SAF7113H enhanced video processor digitizes one of two incoming analogue com-
posite video signals (PAL or NTSC standard) and converts it to a standard 8-bit wide ITU 656 compliant
YUV 4:2:2 signal. That signal can be captured by Ravin-E, optionally scaled up or down and then
stored in the SDRAM. In the video output path, the format can be converted on the fly from YUV to
RGB. See the SAA7113H Product Specification from Philips and the Ravin-E Data Sheet for details.
Ravin-E
µPD72255
SAA7113H
digital
3 V / 5 V buffers
analogue
video drivers
96-pin
DIN
256 Mb x 16
256 Mb x 16
8-bit
analogue
RGB
digital
RGB
to
host
CPU
board