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Rev.2.00 Nov 28, 2005 page 71 of 378
REJ09B0124-0200
M16C/6N Group (M16C/6NK, M16C/6NM) 8. Clock Generating Circuit
Under development
This document is under development and its contents are subject to change.
8.4.2 Wait Mode
In wait mode, the CPU clock is turned off, so are the CPU (because operated by the CPU clock) and the
watchdog timer. However, if the PM22 bit in the PM2 register is “1” (on-chip oscillator clock for the watchdog
timer count source), the watchdog timer remains active. Because the main clock, sub clock and on-chip
oscillator clock all are on, the peripheral functions using these clocks keep operating.
8.4.2.1 Peripheral Function Clock Stop Function
If the CM02 bit in the CM0 register is “1” (peripheral function clocks turned off during wait mode), the f1,
f2, f8, f32, f1SIO, f8SIO, f32SIO, fAD, fCAN0 and fCAN1 clocks are turned off when in wait mode, with
the power consumption reduced that much. However, fC32 remains on.
8.4.2.2 Entering Wait Mode
The microcomputer is placed into wait mode by executing the WAIT instruction.
When the CM11 bit = 1 (CPU clock source is the PLL clock), be sure to set the CM11 bit in the CM1
register to “0” (CPU clock source is the main clock) before going to wait mode. The power consumption
of the chip can be reduced by setting the PLC07 bit in the PLC0 register to “0” (PLL stops).
8.4.2.3 Pin Status During Wait Mode
Table 8.4 lists the pin status during wait mode.
Table 8.4 Pin Status During Wait Mode
NOTES:
1. Not available memory expansion and microprocessor modes in T/V-ver..
2. Not available the bus control pins in T/V-ver..
8.4.2.4 Exiting Wait Mode
______
The microcomputer is moved out of wait mode by a hardware reset, NMI interrupt or peripheral function
interrupt.
______
If the microcomputer is to be moved out of wait mode by a hardware reset or NMI interrupt, set the
peripheral function interrupt priority ILVL2 to ILVL0 bits to “000b” (interrupt disabled) before executing
the WAIT instruction.
The peripheral function interrupts are affected by the CM02 bit. If the CM02 bit is “0” (peripheral function
clocks not turned off during wait mode), peripheral function interrupts can be used to exit wait mode. If
the CM02 bit is “1” (peripheral function clocks turned off during wait mode), the peripheral functions
using the peripheral function clocks stop operating, so that only the peripheral functions clocked by
external signals can be used to exit wait mode.
Table 8.5 lists the interrupts to exit wait mode.
Pin
Memory Expansion Mode
Single-chip Mode
Microprocessor Mode
(1)
A0 to A19, D0 to D15, Retains status before wait mode Does not become a bus control pin
_______ _______ ________
CS0 to CS3, BHE
(2)
______ _______ _________ _________
RD, WR, WRL, WRH
(2)
“H”
___________
HLDA, BCLK
(2)
“H”
ALE
(2)
“L”
I/O ports Retains status before wait mode Retains status before wait mode
CLKOUT Does not become a CLKOUT pin Does not stop
•CM02 bit = 0: Does not stop
•CM02 bit = 1: Retains status before
wait mode
When fC selected
When f8, f32
selected