7733 datasheet(338/940 Pages) RENESAS

Il numero della parte	7733

Spiegazioni elettronici	16-BIT SINGLE-CHIP MICROCOMPUTER

PDF	940 Pages

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Produttore elettronici	RENESAS [Renesas Technology Corp]

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CONNECTING EXTERNAL DEVICES

7733 Group User’s Manual

12–13

12.2 Software wait

The software wait facilitates access to external devices which require a long access time. There are two

types of software waits: wait 0 and wait 1.

The software wait is set by the wait bit (bit 2 at address 5E16) and the wait selection bit (bit 0 at address

5F16). (Refer to Table 12.2.1.) Figure 12.2.1 shows the structures of the processor mode register 0 (address

5E16) and processor mode register 1 (address 5F16). Figure 12.2.2 shows bus timing examples when the

software wait is used.

The software wait is valid only for the external area. (Access to the internal areas is always performed with

no wait.)

Table 12.2.1 Setting method of software wait

Wait bit

Wait selection bit

Software wait

Bus cycle

Invalid (No wait)

Wait 0

Wait 1

Cycle of “internal clock

φ divided by 2”

(clock

φ1’s cycle ! 2)

“Cycle in the no-wait state” ! 2

(clock

φ1’s cycle ! 4)

“Cycle in the no-wait state” ! 1.5

(clock

φ1’s cycle ! 3)

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