ADSP-BF535 Blackfin Processor Hardware Reference
13-13
PCI Bus Interface
A problem arises on writes because the internal bus protocols employed on
the ADSP-BF535 processor support only byte, half word, and word
transfers. In an effort to avoid the complexity of breaking writes into mul-
tiple transactions, all writes are assumed to have contiguous byte enables
and the number of bits written to is rounded up to the nearest supported
transfer size. This means that attempting to write from PCI to only the
first and third bytes results in writing to the whole word, with possible
corruption of data.
Host Mode Operation
When the ADSP-BF535 processor is in host mode, the core acts as the sys-
tem processor with the PCI interface acting as its host-to-PCI bridge. The
ADSP-BF535 processor is put into host mode by setting the Host/Device
Switch bit in the
PCI_CTL
register. In host mode, the core must perform
PCI configuration on any devices attached to the PCI bus. The core must
also configure the ADSP-BF535 processor PCI configuration space, since
it is not accessible from the PCI bus side in host mode. The programmer
should carefully review the values put into the PCI configuration registers
to be sure that all required functionality is enabled correctly.
Outbound Transactions (ADSP-BF535 Processor as
PCI Initiator)
Outbound transactions in host mode are accomplished by the same
method as in device mode. The only difference is that the ADSP-BF535
processor is responsible for configuring the devices on the PCI bus for cer-
tain memory ranges.
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...