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72
DMx820 User’s Manual
18
DAC Chain Load.
When set to 1, enables the
descriptor to load the PCI Dual Address Cycles value.
Otherwise, the descriptor loads the DMADAC0 register
contents.
Yes
Yes
0
x
19
EOT# End Link.
Used only for DMA Scatter/Gather
transfers. Value of 1 indicates that when EOT# is
asserted, the DMA transfer ends the current
Scatter/Gather link and continues with the remaining
Scatter/Gather transfers. Value of 0 indicates that when
EOT# is asserted, the DMA transfer ends the current
Scatter/Gather transfer and does not continue with the
remaining Scatter/Gather transfers.
Yes
Yes
0
0
20
Ring Management Valid Mode Enable.
Value of 0
indicates the Ring Management Valid bit (DMASIZ0[31])
is ignored. Value of 1 indicates the DMA descriptors are
processed only when the Ring Management Valid bit is
set (DMASIZ0[31]=1). If the Valid bit is set, the transfer
count is 0, and the descriptor is not the last descriptor in
the chain. The DMA Controller then moves to the next
descriptor in the chain.
Note:
Descriptor Memory fields are re-ordered when this
bit is set.
Yes
Yes
0
x
21
Ring Management Valid Stop Control.
Value of 0
indicates the DMA Scatter/Gather controller
continuously polls a descriptor with the Valid bit set to 0
(invalid descriptor) if Ring Management Valid Mode is
enabled (DMAMODE0[20]=1). Value of 1 indicates the
Scatter/Gather controller stops polling when the Ring
Management Valid bit with a value of 0 is detected
(DMASIZ0[31]=0). In this case, the CPU must restart
the DMA Controller by setting the Start bit
(DMACSR0[1]=1). A pause clearing the Start bit
(DMACSR0[1]=0) sets the DMA Done bit
(DMACSR0[4]=1).
Yes
Yes
0
x
31:22
Reserved
Yes
No
0
0
DMAPADRn
DMA PCI Address
Bit
Description
Read Write
Value
after
Reset
Value
to Use
31:0
PCI Address.
Indicates from where in PCI
Memory space
DMA transfers (reads or writes) start.
Value is a physical address.
Yes
Yes
0h
x
DMALAPADRn
DMA Local Address
Bit
Description
Read Write
Value
after
Reset
Value
to Use
31:0
DMA Channel Local Address.
Indicates from
where in Local Memory space DMA transfers
(reads or writes) start.
Yes
Yes
0h
x
DMASIZn
DMA Transfer Size