ADSP-BF535 Blackfin Processor Hardware Reference
18-13
External Bus Interface Unit
For bit descriptions of the two registers, see
Figure 18-4
(Asynchronous
Memory Bank Control 0 Register) and
Figure 18-5
(Asynchronous Mem-
ory Bank Control 1 Register).
ARDY Input Control
Each bank can be programmed to sample the
ARDY
input after the read or
write access timer has counted down or to ignore this input signal. If
enabled and disabled at the sample window,
ARDY
can be used to extend
the access time as required. Note that
ARDY
is
synchronously
sampled,
therefore:
• Assertion and deassertion of
ARDY
to the ADSP-BF535 processor
must meet the data sheet setup and hold times. Failure to meet
these synchronous specifications could result in meta-stable behav-
ior internally. The ADSP-BF535 processor’s
CLKOUT
signal should
be used to ensure synchronous transitions of
ARDY
.
• The
ARDY
pin must be stable (either asserted or deasserted) at the
external interface on the cycle
before
the internal bank counter
reaches zero. That is, more than one
CLKOUT
cycle before the sched-
uled rising edge of
AWE
or
ARE
. This will determine whether the
access is extended or not.
• Once the transaction has been extended by the assertion of
ARDY
,
the transaction completes in the cycle
after
ARDY
is sampled
asserted.
The polarity of
ARDY
is programmable on a per-bank basis. Since
ARDY
is
not sampled until an access is in progress to a bank in which the
ARDY
enable is asserted,
ARDY
does not need to be driven by default.
For more
information, see “Adding Additional Wait States” on page 18-26.
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...