7702 Datasheet, PDF (346/522 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
17.1 Memory expansion
_

When
using
external
memory
that
outputs
data
within
tpxz(E-P1Z/P2Z)
after
falling
edge
of
E
_
signal
Because the external memory outputs data within tpxz(E-P1Z/P2Z) after the falling edge of the E signal,
there will be a possibility of the _{_}ta_{_}il of address colliding with the head of data. In th_{_}is case,
generate the memory read signal (OE) by delaying only the leading edge of the fall of the E. (Refer
to Figure 17.1.10.)
E
External memory
output enable signal OE
(Read signal)
Address output
Address
d
tpxz(E-P1Z/P2Z)
Address
External memory
data output
Data
ta(OE)
ten(OE)
: Specifications of the M37702
(The others are specifications of external memory.)
Note: Satisfy tpxz(E-P1Z/P2Z) ≤ ten(OE)+d.
If ten(OE) ≤ tpxz(E-P1Z/P2Z) (= 5 ns), ensure a certain time (i.e., ‘d’ in this diagram)
by delaying the falling edge of OE after the falling edge of E .
Fig. 17.1.10 Example of causing to delay data output timing
17–14
7702/7703 Group User’s Manual