ADSP-BF535 Blackfin Processor Hardware Reference
9-23
Direct Memory Access
No data packing is done on 8- or 16-bit transfers. These modes exist to
support the alignment function, as required. The highest throughput is
achieved with 32-bit transfers.
Use extreme caution when programming start addresses and trans-
fer count to make sure that the DMA channel does not access
unsupported memory, MMR space, scratchpad, or other critical
system resources. Access to illegal memory ranges causes an
exception.
Peripheral DMA Next Descriptor Pointer Register
The value of the peripheral’s DMA Next Descriptor Pointer register deter-
mines the lower 16 bits of the descriptor block base address for the next
DMA transfer sequence. After initial configuration of the DMA register
set, this register is updated whenever the DMA channel fetches a new
descriptor block from memory.
Figure 9-8
describes the peripheral DMA
Next Descriptor Pointer register.
The LSB of this register must always be 0, because the descriptor list must
be 16-bit aligned. This register is not used for autobuffer mode.
Figure 9-8. Peripheral DMA Next Descriptor Pointer Register
Peripheral DMA Next Descriptor Pointer Register
15 14
13 12
11 10
9
8
7
6
5
4
3
2
1
0
0
Next Descriptor
Pointer[15:0]
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Reset = 0x0000
For MMR assign-
ments, see
Table 9-8
.
Содержание ADSP-BF535 Blackfin
Страница 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Страница 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 908: ...SDRAM Controller External Bus Interface Unit B 36 ADSP BF535 Blackfin Processor Hardware Reference...