CS4281 Programming Manual
DS308PRM1
97
Confidential Draft
3/7/00
11.5
DMA Control Registers
11.5.1
DMA Base Address n (DBAn)
Address:
BA0: 118h, Read-Write, for DMA Engine 0
BA0: 128h, Read-Write, for DMA Engine 1
BA0: 138h, Read-Write, for DMA Engine 2
BA0: 148h, Read-Write, for DMA Engine 3
Default:
00000000h
Definition: Core powered. Holds the host base address of the DMA data buffer. When this register is loaded,
the DMA Current Address register is loaded with the same value. This register reloads the DMA
Current Address Register during auto-initialize operation. In Host mode, this is a 32-bit linear
base address. The DMAn controller can transfer data a sample at a time or a channel at a time. If
DMRn.TBC
is set, data will always be transferred a channel at a time regardless of alignment. If
the data is stereo (
DMRn.MONO
= 0), the lower two bits of this register determine the number of
bus cycles needed for one sample for 8- and 16-bit stereo formats. For 8-bit stereo format, if
BAL0
= 0, the sample is word aligned and the DMA controller will transfer complete samples in
one PCI bus cycle. If
BAL0
= 1, the sample is mis-aligned and the DMA controller will transfer
the samples in 2 PCI bus cycles - one for each channel. For 16-bit stereo format,
BAL0
must be 0
since channels are atomic on the CS4281. If
BAL1
= 0, the sample is dword aligned and the DMA
controller will transfer complete samples in one PCI bus cycle. If
BAL1
= 1, the sample is mis-
aligned and the DMA controller will transfer the samples in 2 PCI bus cycles - one for each 16-bit
channel. See Table 2 below.
Bit Descriptions:
BAUH[7:0] Base Address - Upper word, High byte: Most significant byte of the base address in host
mode.
BAUL[7:0] Base Address - Upper word, Low byte: Third byte of base address in host mode.
BAH[7:0] Base Address - lower word, High byte.
BAL[7:0]
Base Address - lower word, Low byte
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
BAUH7
BAUH6
BAUH5
BAUH4
BAUH3
BAUH2
BAUH1
BAUH0
BAUL7
BAUL6
BAUL5
BAUL4
BAUL3
BAUL2
BAUL1
BAUL0
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
BAH7
BAH6
BAH5
BAH4
BAH3
BAH2
BAH1
BAH0
BAL7
BAL6
BAL5
BAL4
BAL3
BAL2
BAL1
BAL0
D
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