7733 datasheet(365/940 Pages) RENESAS

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CLOCK GENERATING CIRCUIT

7733 Group User’s Manual

14–2

14.1 Overview

Quartz-crystal oscillator

Pins XCIN and XCOUT

Not available

Stopped (Note 1)

• A clock which is externally

generated can be input.

• Sub clock can be input to external

devices. (Refer to 14.3.1.)

Usage of clock

Resonator/Oscillator

which can be connected

Pins which are connected to

resonator/oscillator

Oscillation stop/restart (Note 2)

Oscillator’s state just after

reset

Remarks

• Operating clock source of CPU

• Operating clock source of internal

peripheral devices

• Operating clock source of clock timer

• Ceramic resonator

• Quartz-crystal oscillator

Pins XIN and XOUT

Available

Operating

A clock which is externally generated

can be input.

Main-clock oscillation circuit

Sub-clock oscillation circuit

Notes 1: Immediately after reset, pins XCIN and XCOUT function as ports P77 and P76, respectively. The

oscillator starts operating when pins’ function is switched by the port-XC selection bit (bit 4 at

address 6C16).

2: Whether oscillation is stopped or restarted is set by the main clock stop bit (bit 2 at address 6C16).

In the main-clock/sub-clock oscillation circuit, oscillation can be stopped by the STP instruction;

oscillation can be restarted by an interrupt request generated. (Refer to Figure 14.3.9.)

The clock generating circuit is described below.

14.1 Overview

This clock generating circuit includes two oscillation circuits, which are main-clock and sub-clock oscillation

circuits. Each of the main and sub clocks can be used as an operating clock for the CPU, internal peripheral

devices, and clock timer.

Table 14.1.1 Main-clock and sub-clock oscillation circuits

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