Fusion 878A
5.0 Control Register Definitions-Function 0
PCI Video Decoder
5.3 Local Registers (Memory Mapped)
100600B
Conexant
5-25
0x078—White Crush Down Register
This control register may be written to or read by the MPU at any time, and upon reset is initialized to 0x7F.
DNCNT(0) is the least significant bit. This register is programmed with a two’s complement number.
0x080—Timing Generator Load Byte (TGLB)
Upon reset, TGLB is initialized to 00.
[7]
RW
0
VERTEN
0 = Normal operation
1 = Enable vertical sync detection in determining the video presence (PRES)
status.
[6]
RW
1
WCFRAME
This bit programs the rate at which the DNCNT and UPCNT values are
accumulated.
0 = Once per field
1 = Once per frame
[5:0]
RW
0x22F
DNCNT
The value programmed in these bits accumulates once per field or frame. The
accumulated value determines the extent to which the AGC value needs to be
lowered in order to keep the SYNC level proportionate to the white level.
The DNCNT value is assumed negative. For example:
3F= –1
3E= –2
. . .
. . .
. . .
00= –64
[7:0]
RW
00
Reading from this address reads only the current byte. The TGC_AI bit must be
pulsed by software in order for the SRAM byte location to advance.