SA1110 Datasheet, PDF (165/406 Pages) Intel Corporation – Intel StrongARM SA-1110 Microprocessor

Memory and PCMCIA Control Module
10.5.7 FLASH Memory Interface Overview
The SA-1110 provides an SRAM-like interface for access of Flash memory. The RDF fields in the
MSCx registers are the latency for each read access to nonburst Flash or the first read access to
burst Flash; it also controls the nWE low time during a write cycle (nonburst) to burst Flash. The
RDN field controls subsequent read access times to burst Flash and the nWE low time during a
write cycle to nonburst Flash. RRR is the time from nCS deassertion after a read to the start of a
read from a different memory or after a write to another memory access. A single DRAM CBR
refresh cycle may be inserted between words of a burst read from Flash memory. During the
refresh cycle, nCS and nOE will be deasserted.
There are some requirements for writes to Flash memory. Flash memory space must be uncacheable
and unbuffered. Writes must be exactly the width of the populated Flash devices on the data bus (no
byte writes to a 32-bit bus or word writes to a 16-bit bus, and so on). Software is responsible for
partitioning commands and data, and writing them out to Flash in the appropriate sequence.A single
CBR refresh cycle, for asynchronous DRAM and/or SDRAM, may be inserted between word
accesses within a burst read. nCS and nOE are deasserted during the refresh cycle.
10.5.8 FLASH Memory Timing Diagrams and Parameters
Nonburst Flash reads have the same timing as nonburst ROMs as shown in the preceding figures.
Figure 10-18 shows the timing for writes to nonburst Flash. Writes to burst Flash use nonburst
accesses and equivalent timings, except that the nWE assertion time and data setup use RDF+1
instead of RDN+1.
Figure 10-18. Flash Write Timing Diagram (2 Writes)
CPU
Clock
Memory
Clock
Write Command
t_CEH
t_AS
Write Data
max (2*RRR,1)
nCS0
A(25:0)
nWE
t_ASW t_AH
A0
t_CES
t_DSWH
RDN+1
A1
RDN+1
Possible Read or Write
nOE
RD/nWR
t_DH
D(31:0)
CMD
Data
Note: If RT=00 then RDN+1. If RT=1x, then RDF+1
A6656-02
SA-1110 Developer’s Manual
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