User's 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 Normal processing
XIN stops
XIN
fRING
(1)
CPU
operation
Oscillation stop, re-oscillation
detection interrupt request
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.