
Rev. 2.0, 09/02, page 114 of 366
These buffers are used by the Q2SD to temporarily store data held in the UGM. The Q2SD uses
the data stored in these buffers when executing drawing. The functions of these buffers are as
follows:
1. Command buffer (32 bytes
×
2)
Used by the Q2SD to store a display list held in the UGM. The buffer size is 64 bytes.
2. Source buffer (64 bytes)
Used by the Q2SD to store a binary source or multi-valued source held in the UGM. The
buffer size is 64 bytes.
3. Work buffer (16 bytes)
Used by the Q2SD when performing drawing at binary work coordinates in the UGM. The
buffer size is 16 bytes.
When buffer contents are not updated, (when the same address is referenced by data of or below
the capacity of the buffer, or a reference ends at a location at or below the capacity of the buffer
from the previous reference start location), the previous buffer contents will be used even though
the data in the UGM is rewritten. To intentionally update buffer contents, the address of a
location exceeding the buffer capacity should be referenced.
3.6
Video Capture
The Q2SD can incorporate a YUV 4:2:2 8-bit data stream obtained by digital encoding of NTSC
signals. The captured data is displayed on the video screens.
3.6.1
Configuring Circuit for Video Capture
(1) Video Capture Operation
Video capture is performed at the rising edge of the VQCLK signal. The 8-bit data stream
corresponding to the number of pixels set in the VSIZEX field in the video window size register
(VSIZER) is captured for each VHS signal and transferred to one of three video storage areas
determined by video area start address registers (VSAR). These areas are used sequentially in
frame units. The video window status bits (VID0, VID1) are valid when 0 is set in the video
incorporation enable bit (VIE) and indicate the most recent video area in which video capture
has been completed. The size of the video storage areas is determined by VSIZEX and VSIZEY.
Use a frequency not exceeding 1/2 the system operating clock frequency for VQCLK (the
system operating clock should be in the range 64 to 66 MHz). A number of VQCLK cycles
equal to twice the number of luminous pixels are necessary per VHS.
996
,
9+6
,
92''
and
VQCLK are accepted following hardware reset release, and video capture is started by setting
VIE to 1, having the first VVS signal sync signal input, then having the first VHS signal sync
signal input.