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RTD Embedded Technologies, Inc.
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70
DMx820 User’s Manual
PLX Registers
The PLX9056 PCI Accelerator on the DMx820HR contains several registers to control interrupts and the two DMA engines. These engines
allow data to be transferred on-demand with no load on the processor. The following sections describe the registers used for programming the
DMA engines. This information is taken from PLX PCI9065BA Datasheet. For more information, please consult the datasheet.
6.4.1
M
EMORY
M
AP
O
VERVIEW
Table 16 shows the memory map of the DMx820HR DMA registers. These are found at the memory offset from BAR0, or the I/O offset from
BAR1.
Table 16: PLX DMx820HR Memory Map
Offset (Hex)
Register Name
Register Description
DMA Channel 0
0x80
DMAMODE0
DMA Channel 0 Mode
0x84
0x88
DMAPADR0
DMA Channel 0 PCI Address
0x88
0x8C
DMALADR0
DMA Channel 0 Local Address
0x8C
0x84
DMASIZ0
DMA Channel 0 Transfer Size (Bytes)
0x90
DMADPR0
DMA Channel 0 Descriptor Pointer
DMA Channel 1
0x94
DMAMODE1
DMA Channel 1 Mode
0x98
0x9C
DMAPADR1
DMA Channel 1 PCI Address
0x9C
0xA0
DMALADR1
DMA Channel 1 Local Address
0xA0
0x98
DMASIZ1
DMA Channel 1 Transfer Size (Bytes)
0xA4
DMADPR1
DMA Channel 1 Descriptor Pointer
Command and Status
0xA8
DMACSR0
DMA Channel 0 Command/Status
0xA9
DMACSR1
DMA Channel 1 Command/Status
0xAC
DMAARB
DMA Arbitration
0xB0
DMATHR
DMA Threshold
0xB4
DMADA0
DMA Channel 0 PCI Dual Address Cycle
Upper Address
0xB8
DMADA1
DMA Channel 1 PCI Dual Address Cycle
Upper Address
Interrupt
0x68
INTCSR
Interrupt Control/Status
Where two addresses are given, the left column is the address when
DMAMODEn[20] =0, and the right column is the address when DMAMODEn[20] =1.
6.4.2
DMA
R
EGISTER
D
ESCRIPTION
DMAMODEn
DMA Mode
Bit
Description
Read Write
Value
after
Reset
Value
to Use
1:0
Local Bus Data Width.
Writing of the following values
indicates the associated bus data width:
00b = 8 bit
01b = 16 bit
10b or 11b = 32 bit
Yes
Yes
11b
11b
5:2
Internal Wait State Counter
(Address-to-Data; Data-to-
Data; 0 to 15 Wait States).
Yes
Yes
0h
0h