ADSP-BF535 Blackfin Processor Hardware Reference
18-25
External Bus Interface Unit
For MemDMA accesses through AMC, 2
SCLK
cycles are required from
the time the read data is sampled until the next setup period begins. As a
result, if the hold period programmed is less than 2 cycles,
AMS[x]
and
AOE
deassert between accesses within a burst. Regardless of hold period pro-
gramming, if the access is the last in the burst,
AMS[x]
and
AOE
deassert for
6 cycles before the next burst begins.
Figure 18-11
also shows a MemDMA read access of 16 words from exter-
nal memory. In this case, the asynchronous memory controller is
programmed with setup = 1 cycle, read access = 3 cycles, hold = 1 cycle,
and transition time = 1 cycle. This is a smaller number of hold cycles than
programmed in
Figure 18-10
.
The MemDMA access proceeds as:
• At the start of the setup period,
AMS[x]
, the address bus, and
ABE[3:0]
become valid, and
AOE
asserts.
• At the beginning of the read access period and after the setup cycle,
ARE
asserts.
• At the beginning of the hold period, read data is sampled on the
rising edge of the EBIU clock. The
ARE
pin deasserts after this ris-
ing edge.
• At the end of the hold period,
AOE
and
AMS[x]
deassert.
Figure 18-11. MemDMA Read With 1-Cycle Hold
AMS[x ]
AOE
ARE
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...