Asynchronous Memory Interface
18-26
ADSP-BF535 Blackfin Processor Hardware Reference
Asynchronous Writes
Figure 18-12
shows a MemDMA write access of 16 words to external
memory. The asynchronous memory controller is programmed with setup
= 1 cycle, write access = 3 cycles, hold = 0 cycles, and transition time = 1
cycle.
The MemDMA access proceeds as:
• At the start of the setup period,
AMS[x]
, the address bus, data buses,
and
ABE[3:0]
become valid.
• At the beginning of the write access period and after the setup
cycle,
AWE
asserts.
• At the beginning of the hold period,
AWE
deasserts.
• At the end of the hold period,
AMS[x]
deasserts if the transaction is
the last in the burst, otherwise
AMS[x]
remains asserted for the
setup period of the next write.
Adding Additional Wait States
The
ARDY
pin is used to insert extra wait states. The input is sampled syn-
chronously with the EBIU internal clock. The EBIU starts sampling
ARDY
on the clock cycle before the end of the programmed strobe period. If
ARDY
is sampled deasserted, the access period is extended. The
ARDY
pin is
then sampled on each subsequent clock edge. Read data is latched on the
clock edge after
ARDY
is sampled asserted. The read- or write-enable
remains asserted for one clock cycle after
ARDY
is sampled asserted. An
Figure 18-12. MemDMA Write
AMS[x ]
AWE
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...