Functional Description
5-44
ADSP-BF537 Blackfin Processor Hardware Reference
The block done interrupt signals that a complete MDMA block as defined
by the
HMDMAx_BCINIT
register has been transferred, that is, when the
HMDMAx_BCOUNT
register decrements to zero. While the
BDIE
bit enables this
interrupt, the
MBDI
bit can gate it until the edge count also becomes zero,
meaning that all requested MDMA transfers have been completed.
The overflow interrupt is generated when the
HMDMA_ECOUNT
register over-
flows. Since it can count up to 32767, which is much more than most of
peripheral devices can support, the Blackfin processor features another
threshold register called
HMDMA_ECOVERFLOW
. It resets to
0xFFFF
and should
be written with any positive value by the user before enabling the function
by the
OIE
bit. Then, the overflow interrupt is issued when the value of the
HMDMA_ECOUNT
register exceeds the threshold in the
HMDMA_ECOVERFLOW
register.
DMA Performance
The DMA system is designed to provide maximum throughput per chan-
nel and maximum utilization of the internal buses, while accommodating
the inherent latencies of memory accesses.
The Blackfin architecture features several mechanisms to customize system
behavior for best performance. This includes DMA channel prioritization,
traffic control, and priority treatment of bursted transfers. Nevertheless,
the resulting performance of a DMA transfer often depends on applica-
tion-level circumstances. For best performance consider these questions
architecting the system software:
• What is the required DMA bandwidth?
• Which DMA transfers have real-time requirements and which do
not?
• How heavily is the DMA controller competing with the core for
on-chip and off-chip resources?
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 ...