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IDT PCI Bus Interface
PCI Master — Memory to PCI DMA (DMA Channel 9)
79RC32438 User Reference Manual
10 - 33
November 4, 2002
Notes
Figure 10.17 Device Command Field for Memory to PCI DMA Descriptors
Figure 10.18 Device Control and Status Value for Memory to PCI DMA Descriptors
Event
Description
DMA Request Event
A request event is generated whenever 16 free words are available in
the PCI DMA output FIFO. Memory to PCI DMA operations will gener-
ate DMA request events during IPBus transactions as long as the above
conditions are met for subsequent data in the FIFO.
DMA Done Event
A DMA done event is never generated.
DMA Terminated Event
A DMA terminated event is generated if any of the following occur: PCI
master terminates transaction with a Master Abort (i.e., no target
responds to transaction), PCI target terminates with a Target Abort,
transaction could not be completed because the RETRY_LIMIT was
exceeded, the transaction could not be completed because the BM bit is
not set in the COMMAND register, and detection of a PCI parity error.
DMA Transfer Size
16 words.
Limitations
None. A DMA operation may start and end on any local address or PCI
address byte boundary and may contain any number of bytes
Table 10.9 Memory to PCI DMA Operations
PT
PCI Transaction.
This field specifies the PCI transaction to use to write data to the PCI bus.
0x0
Memory Write
0x1 Memory Write and Invalidate
0x2
Reserved
0x3 I/O Write
SB
Swap Bytes.
This field control byte swapping for data written to the PCI bus during a memory to
PCI DMA operation.
PCIADDR
PCI Address.
This field specifies the starting PCI address for memory to PCI DMA operations.
DEVCMD
2
2
PT
0
1
SB
DEVCS
0
31
32
PCIADDR