saa6712e NXP Semiconductors, saa6712e Datasheet - Page 46

• Manufacturer Part Number: saa6712e
• Description: Xga Rgb To Tft Graphics Engine
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Table 11 Memory initialization programming
8.5.3
Output frames with the right vertical and horizontal
dimensions must be generated. Since size information is
not stored in the external memory, the output frame
resolution must be programmed into the registers
frame_length and line_length. The first value gives the
vertical resolution, and the second the horizontal
resolution in pixels. If no downscaler is used, these values
can be taken directly from the input interface.
If downscaling is activated, the size of the de-interlacer
output frame must be calculated from the RGB input frame
size divided by the downscaling factors.
If no valid data stream is applied at the RGB input
interface, the de-interlacer is able to generate a picture by
itself. This will be enabled with blank_screen at
address 25. The colour of this frame is defined by
blank_colour_red, blank_colour_green, and
blank_colour_blue.
8.6
Two different scaling units are implemented to perform
both up and downscaling. The downscaling engine, which
is located before the memory interface, and the upscaling
engine after the memory interface.
8.6.1
If the downscaler is to be used, it must be enabled by
setting flags down_v_scaler_on and down_h_scaler_on.
For vertical scaling a line memory buffer is needed.
This memory must be switched to downscaling mode by
setting down_v_scaler_mem to logic 1 because only one
is available.
Setting up the desired downscaling ratios is achieved by
programming the scaling increments down_v_incr,
down_v_corr, and down_h_incr, down_h_corr. This must
be done for both vertical and horizontal scaling.
1999 Aug 25
XGA RGB to TFT graphics engine
Scaling
F
D
STEP
RAME RECOVERY
OWNSCALING
1
2
3
4
5
SAA6712E Power-on reset
set-up timing parameters
start memory initialization with setting memory_init
set-up all other parameters
release internal memory reset together with other internal resets
ACTION
46
Where xx is equivalent to down_v_incr or down_h_incr
and yy is the fraction of the result in
This is the value for programming the increment correction
values down_v_corr and down_h_corr.
Example: SXGA
Horizontal:
This means down_h_incr = 51 and down_h_corr = 20.
Vertical:
This means down_v_incr = 48 and down_v_corr = 0.
8.6.2
The upscaler must be activated by up_v_scaler_on and
up_h_scaler_on. To use the line memory for upscaling,
down_v_scaler_mem must be set to logic 0. To set-up the
zoom factor, the scaling increments up_v_incr, up_v_corr,
up_h_incr, and up_h_corr must be programmed.
Where xx is equivalent to up_v_incr or up_h_incr and yy is
the fraction of the result in
This is the value for programming the increment correction
values up_v_corr and up_h_corr.
Example: XGA
Horizontal:
This means up_h_incr = 80 and up_h_corr = 0.
Vertical:
This means up_v_incr = 85 and up_v_corr = 33.
incr
incr
=
=
number_of_output_pixels
------------------------------------------------------------------ -
number_of_output_pixels
------------------------------------------------------------------ -
number_of_input_pixels
number_of_input_pixels
U
------------ -
1024
1024
------------ -
768
768
PSCALING
1024
------------ -
1280
1280
------------ -
1024
64
64
SXGA
64
64
XGA
=
=
48.00
85.33
=
=
51.20
80.00
1
100
.
Preliminary specification
64
64
1
100
=
SAA6712E
REGISTERS
=
xx.yy
.
51 to 55
50 to 74
xx.yy
24
24