7733 datasheet(695/940 Pages) RENESAS

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CONNECTING EXTERNAL DEVICES

7735 Group User’s Manual

12–19

P42/

φ1

Timers A and B, Serial I/O,

A-D converter,

Watchdog timer

Item

State

12.3 Ready function

The ready function facilitates access to external devices which require a long access time.

____

By applying “L” level to pin RDY in the memory expansion or microprocessor mode, the microcomputer

____

enters the ready state. While pin RDY’s level is “L,” this state is retained. Table 12.3.1 lists the microcomputer’s

state in the ready state.

In the ready state, oscillation of the oscillator does not stop. Therefore, the internal peripheral devices can

operate even in the ready state. The ready function is valid for the internal and external areas.

Table 12.3.1 Microcomputer’s state in ready state

Clock

φ1 output selection bit*1: Bit 7 at address 5E16

Signal output disable selection bit*2: Bit 6 at address 6C16

____

Notes 1: When “L” level which was input to pin RDY is sampled at one of the following timings, this signal

is not accepted. (Note that

φCPU is stopped at “L” level.)

____

q When the levels of signals RDE, WEL, and WEH are “H” while the bus is in use (Refer to in

Figure 12.3.2.)

q Immediately before a wait generated by the software wait (Refer to in Figure 12.3.2.)

2: This is applied when these pins function as programmable I/O ports.

Oscillation

φCPU

Operating

Stopped at “L” level

____

Retains the same state in which RDY was accepted.

In the memory expansion mode

s When the clock

φ1 output selection bit*1 = “1”

Outputs clock

φ1.

s When the clock

φ1 output selection bit = “0”

____

Retains the same state in which RDY was accepted.

In the microprocessor mode

s When the signal output disable selection bit*2 = “1”

____

Retains the same state in which RDY was accepted.

s When the signal output disable selection bit = “0”

Outputs clock

φ1.

Operating

____

RDE

, WEL, WEH, CS0

to CS4,

_____

HLDA

, ALE, A 0/D0 to A 15/D15,

A16, A17

P43 to P47, P5 to P8 (Note 2)

12.3 Ready function

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