MC68340FE16E Datasheet, PDF (393/441 Pages) Freescale Semiconductor, Inc – Integrated Processor with DMA User’s Manual

Freescale Semiconductor, Inc.
CLKOUT
S0 S1 S2 SW SW SW SW S3 S4 S5 S0 S1 S2
CS0
Q1
DSACK0
Figure 10-9. 8-bit Boot ROM Timing
10.2.2 Access Time Calculations
The two time paths that are critical in an MC68340 application using the CS≈ signals are
shown in Figure 10-10. The first path is the time from address valid to when data must be
available to the processor; the second path is the time from CS≈ asserted to when data
must be available to the processor.
S0
S1
S4
S5
S0
CLKOUT
t6
A31–A0
t9
CS
D15–D0
t _CSDV
t ₂₇
t _ADV
Figure 10-10. Access Time Computation Diagram
As shown in the diagram, an equation for the address access time, tADV, can be
developed as follows:
tADV = tcyc(Nc – 0.5) – ts9 – ts27
where:
tcyc = system CLKOUT period
Nc = number of clocks per bus cycle
ts6 = CLKOUT high to address valid = 30 ns maximum at 16.78 MHz
ts27 = data-in valid to CLKOUT low setup = 5 ns minimum at 16.78 MHz
10-6
MC68340 USER’S MANUAL
MOTOROLA
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