7733 datasheet(416/940 Pages) RENESAS

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APPLICATIONS

7733 Group User’s Manual

17–9

(2) Timing for writing data

Figure 17.1.5 shows the timing for writing data to an external memory.

When data is written, the data is output from when an interval of td(E-DQ) has passed after signal E’s

falling edge until an interval of th(E-DQ) has passed after signal E’s rising edge. Table 17.1.4 lists the

value of td(E-DQ) and the calculation formula for th(E-DQ).

Make sure that the data output timing for writing data satisfies the following specifications of the

external memory: data setup time (tsu(D)) and data hold time (th(D)) for writing data.

Fig. 17.1.5 Timing at which data is written to external memory

Table 17.1.4 Value of td(E-DQ) and calculation formula for th(E-DQ) (Unit: ns)

Wait 0

Wait 1

– 22

1 ! 109

2•f(f2)

No wait

0 or 1

Wait bit: Bit 2 at address 5E16

Wait selection bit: Bit 0 at address 5F16

Note: The above is applied when the system clock selection bit (bit 3 at address 6C16) = “0.”

17.1 Memory expansion

External memory

write signals

W, WE

External memory

chip select signals

CE, S

(The others are specifications of

external memory.)

: Specifications of

the 7733 Group

g This is applied when the external

data bus = 16 bits wide (BYTE = “L” ).

Address and data output

/D8 to A15/D15

A16/D0 to A23/D7

tsu(D)

th(D)

Address

Data

Address

tw(EL)

th(E-DQ)

td(E-DQ)

Software wait

Wait bit

Wait selection bit

td(E-DQ)

th(E-DQ)

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