Renesas M16C User Manual

Rev.1.10 Jul 01, 2005 page 284 of 318
REJ09B0124-0110

M16C/6N Group (M16C/6NK, M16C/6NM)

22. Usage Precaution

Under development

This document is under development and its contents are subject to change.

22.5 Oscillation Stop, Re-oscillation Detection Function

If the following conditions are all met, the following restriction occur in operation of oscillation stop,

re-oscillation stop detection interrupt.

Conditions

• CM20 bit in CM2 register =1 (oscillation stop, re-oscillation stop detection function enabled)

• CM27 bit in CM2 register =1 (oscillation stop, re-oscillation stop detection interrupt)

• CM02 bit in CM0 register =0 (do not stop peripheral function clock in wait mode)

• Enter wait mode from high-speed or middle-speed mode

Restriction

If the oscillation of XIN stops during wait mode, the oscillation stop, re-oscillation stop detection interrupt

request is generated after the microcomputer is moved out of wait mode, without starting immediately.

Figures 22.1 and 22.2 show the operation timing at oscillation stop, re-oscillation stop detection.

Figure 22.1 Operation Timing at Oscillation Stop, Re-oscillation Stop Detection at Wait Mode

________

(when moving out of wait mode by using INT0 interrupt)

Figure 22.2 Operation Timing at Oscillation Stop, Re-oscillation Stop Detection at Normal Processing

Wait mode

XIN

fRING

(1)

INT0 input

CPU
operation

Oscillation stop, re-oscillation
detection interrupt request

INT0 interrupt request

XIN stops

Wait mode is released

NOTE:

1. This clock is generated by the on-chip oscillator. It is not supplies after reset.

The operating clock can changes from on-chip oscillator clock (on-chip oscillation oscillating) to BCLK
by using oscicllation stop, re-oscillation detection function or setting the CM21 bit in the CM2 register.

Normal processing