
Rev.2.10 Apr 14, 2006 page 344 of 378
REJ09B0124-0210
M16C/6N Group (M16C/6NK, M16C/6NM) 23. Usage Notes
23.6 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 MCU is exits wait mode, without starting immediately.
Figures 23.1 and 23.2 show the Oscillation Stop, Re-oscillation Stop Detection Operation Timing.
Figure 23.1 Oscillation Stop, Re-oscillation Stop Detection Operation Timing at Wait Mode
________
(when moving out of wait mode by using INT0 interrupt)
Figure 23.2 Oscillation Stop, Re-oscillation Stop Detection Operation Timing 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 oscillation 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 oscillation stop, re-oscillation detection function or setting the CM21 bit in the CM2 register.
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