4-2
Register Descriptions
4.1 Host Interface Registers
Figure 4.1
Register 0 (0x000)
Decode Status Interrupt
0
This bit is set when the video decode status changes
from stopped to running (0 to 1) and cleared when the
status changes from running to stopped (1 to 0). Either
status change causes assertion of the INTRn interrupt
signal to the host if not masked. The 0 to 1 transition
occurs on a picture start code boundary after channel
start. It is linked in timing to the last field of the display
system. The decode status is updated internally and may
change when one of the following events is recognized by
the internal microcontroller:
1. A write to the Decode Start/Stop Command register
(
page 4-57
) by the host.
2. When the Video Start on Compare register (
page 4-16
)
is set by the host and a compare occurs. In this case, the
status goes from stopped to running.
Reading this register does NOT change the Decode
Status bit.
INTRn is not asserted if the host sets the mask bit.
Aux/User Data FIFO Ready Interrupt
When set, indicates there is new data in the Aux or User
Data FIFO ready to be read. A NOT ready (0) to ready
(1) change causes assertion of the INTRn signal if not
masked. The status of the Aux Data FIFO (
page 4-17
)
and User Data FIFO (
page 4-18
) can be read to
determine which has valid data. The bit is cleared on
reading. Even though data remains in the FIFOs, no
further interrupts are generated.
INTRn is not asserted if the host sets the mask bit.
1
7
6
5
4
3
2
1
0
Read
New Field
Interrupt
Audio Sync
Recovery
Interrupt
Reserved
SDRAM
Transfer
Done
Interrupt
Sequence
End Code
Detect
Interrupt
First Slice
Start Code
Detect
Interrupt
Aux/User
Data FIFO
Ready
Interrupt
Decode
Status
Interrupt
Write
New Field
Mask
Audio Sync
Recovery
Mask
Reserved
SDRAM
Transfer
Done Mask
Sequence
End Code
Detect Mask
First Slice
Start Code
Detect Mask
Aux/User
Data FIFO
Ready Mask
Decode
Status Mask