TMS320VC5416
Fixed-Point Digital Signal Processor
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SPRS095O–MARCH 1999–REVISED JANUARY 2005
CLKOUT
A[22:0]
D[15:0]
WRITE
R/W
MSTRB or IOSTRB
PS/DS/IS
Leading
Cycle
Write
Cycle
Trailing
Cycle
Figure 3-15. Memory Write and I/O Write Bus Sequence
The enhanced interface also provides the ability for DMA transfers to extend to external memory. For
more information on DMA capability, see the DMA sections that follow.
The enhanced interface improves the low-power performance already present on the TMS320C5000™
DSP platform by switching off the internal clocks to the interface when it is not being used. This
power-saving feature is automatic, requires no software setup, and causes no latency in the operation of
the interface.
Additional features integrated in the enhanced interface are the ability to automatically insert
bank-switching cycles when crossing 32K memory boundaries (see Section 3.6.2), the ability to program
up to 14 wait states through software (see Section 3.6.1), and the ability to divide down CLKOUT by a
factor of 1, 2, 3, or 4. Dividing down CLKOUT provides an alternative to wait states when interfacing to
slower external memory or peripheral devices. While inserting wait states extends the bus sequence
during read or write accesses, it does not slow down the bus signal sequences at the beginning and the
end of the access. Dividing down CLKOUT provides a method of slowing the entire bus sequence when
necessary. The CLKOUT divide-down factor is controlled through the DIVFCT field in the bank-switching
control register (BSCR) (see Table 3-5).
36
Functional Overview
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