Descriptor Based DMA
9-8
ADSP-BF535 Blackfin Processor Hardware Reference
The DMA controller does not support data packing. For example, in an
8-bit device, if the data size is set up for 32 bits, the upper 3 bytes of the
32-bit transfer are zero-filled.
• Peripheral control (bits 5 and 6)
• Peripheral dependent control bits provide peripheral control
through descriptor blocks. For more information about the use of
these bits in a specific peripheral, see the appropriate peripheral
chapter.
• Peripheral status (bits 9 – 13)
• The peripheral dependent status bits contain peripheral specific
information about the DMA transfer for the current descriptor
block, including buffer status. At the completion of the DMA
transfer, this information is written back to the DMA Configura-
tion Word of the current DMA descriptor block. For more
information about the use of these bits in a specific peripheral, see
the appropriate peripheral chapter.
Setting Up Descriptor Based DMA
The following steps illustrate the typical sequence for setting up descriptor
based DMA.
Before these steps, the DMA Descriptor Base Pointer register
(
DMA_DBP
) must be configured with the upper 16 bits (MSBs) of the
descriptor block base address,
BASE
+0.
1. Write the DMA Configuration Word (with bit 15 set to 1), DMA
Transfer Count, DMA Start Address[15:0], DMA Start
Address[31:16], and Next Descriptor Pointer[15:0] to the descrip-
tor block memory addresses
BASE
+0 through
BASE
+8.
Summary of Contents for ADSP-BF535 Blackfin
Page 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Page 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Page 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Page 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Page 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Page 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Page 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Page 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Page 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Page 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Page 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Page 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Page 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...