ADSP-BF537 Blackfin Processor Hardware Reference
6-5
External Bus Interface Unit
Internal Memory Interfaces
The EBIU functions as a slave on three buses internal to the processor:
• External Access Bus (EAB), mastered by the core memory manage-
ment unit on behalf of external bus requests from the core
• DMA External Bus (DEB), mastered by the DMA controller on
behalf of external bus requests from any DMA channel
• Peripheral Access Bus (PAB), mastered by the core on behalf of sys-
tem MMR requests from the core
These are synchronous interfaces, clocked by
SCLK
, as are the EBIU and
pads registers. The EAB provides access to both asynchronous external
memory and synchronous DRAM external memory. The external access is
controlled by either the AMC or the SDC, depending on the internal
address used to access the EBIU. Since the AMC and SDC share the same
interface to the external pins, access is sequential and must be arbitrated
based on requests from the EAB.
The third bus (PAB) is used only to access the memory-mapped control
and status registers of the EBIU. The PAB connects separately to the
AMC and SDC; it does not need to arbitrate with or take access cycles
from the EAB bus.
The External Bus Controller (EBC) logic must arbitrate access requests for
external memory coming from the EAB and DEB buses. The EBC logic
routes read and write requests to the appropriate memory controller based
on the bus selects. The AMC and SDC compete for access to the shared
resources. This competition is resolved in a pipelined fashion, in the order
dictated by the EBC arbiter. Transactions from the core have priority over
DMA accesses in most circumstances. However, if the DMA controller
detects an excessive backup of transactions, it can request its priority to be
temporarily raised above the core.
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...