
Microcontroller Registers
4-73
is governed by the Rip Forward Display Single Step
Command (bit 1 in this register). The microcontroller
monitors the single step command bit after it has
received a picture start code and processed a picture
header. The decode for that picture only proceeds if the
single step command bit is set. The single step command
bit is cleared on reading by the microcontroller. Rip
Forward Mode is intended to be used in an application
where not every picture that is decoded needs to be
displayed. The picture to be displayed is specied in
separate registers. These registers are decoded in the
Video Interface module. (See Register 265 bits 4 and 5,
Display Override Mode, and Registers 285, 286, 287,
and 288, Override Display Start Addresses for luma and
active, the host must also specify the Override Picture
Width (Register 283, bits [6:0],
page 4-87). Pan and Scan
from the bitstream must be disabled (bit 6 in Register 279
must be cleared,
page 4-86) and pan-scan values (if any)
must be supplied by the host. Bit 2 in Register 275
(
page 4-83), 3:2 Pulldown from bitstream, must be
cleared, and the Host Repeat First Field bit (bit 3 in
Register 275) and Host Top Field First bit (bit 4 in
Register 275) must be used by the host to specify the
display completely.
Rip Forward Display Single Step Status
R 1
Indicates the status of the Rip Forward Display Single
Step Command as described following.
Rip Forward Display Single Step Command
W 1
This bit should be set by the host after it has made the
decision on whether or not to display the current picture.
The L64021’s microcontroller waits for this bit to be set
before continuing with picture reconstruction in Rip
Forward Mode. This bit is only applicable when the Rip
Forward Mode Enable bit (bit 0 in this register) is set. The
microcontroller clears this bit when it reads it.