Texas Instruments TMS320C64x DSP - Manual (Page 42)

DMA Operation
2-9 Video Port SPRU629
Figure 2–2. Display DMA Event Generation Flow Diagram
Start of field
FIFO empty
Generate DMA event,
new events disabled
Display data, no DMA
pending
F ield complete
?
Underrun error
FIFO underrun
?
Display data
EOF
No
Underrun error
Underrun error
FIFO underrun
?
No
Pending
DMA begun ?
Yes
Display data, DMA
active, new events
enabled
Underrun error
FIFO
underrun ?
Yes
No
FIFO underrun
?
DMA complete
?
Event counter
expired ?
No
Display Data, DMA active,
and DMA pending
Generate DMA
request
FIFO space
2x threshold
?
No
Yes
No
Yes
EOF
DMA complete
?
Yes
No No
EOF
Yes
No
Event counter
expired ?
Display data, DMA
pending, new events
disabled
Pending DMA
begun ?
Generate DMA event
Yes
Yes
No
No
FIFO underrun
?
No Yes
Yes
No
FIFO space
threshold ?
No
Yes
Underrun error
Yes
Yes
End of field
Yes