Wait Mode - Renesas M16C/60 Series Hardware Manual

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This document is under development and its contents are subject to change.
M16C/6N5 Group

(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 of PM2 register is "1" (ring oscillator clock for the watchdog
timer count source), the watchdog timer remains active. Because the main clock, sub clock, ring oscillator
clock and PLL clock all are on, the peripheral functions using these clocks keep operating.
• Peripheral Function Clock Stop Function
If the CM02 bit is "1" (peripheral function clocks turned off during wait mode), the f
f , f and f
32SIO AD CAN0
much. However, f
• 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 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 to "0" (PLL stops).
• Pin Status During Wait Mode
Table 1.8.4 lists the pin status during wait mode.
Table 1.8.4 Pin Status During Wait Mode
Pin
A to A , D to D ,
0 19 0 15
_______ _______ ________
CS to CS , BHE
0 3
______ _______ _________ _________
RD, WR, WRL, WRH
___________
HLDA, BCLK
ALE
I/O ports
CLK When f selected
OUT C
When f , f
8 32
selected
• 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 exit wait mode by a hardware reset or NMI interrupt, set the
peripheral function interrupt priority ILVL2 to ILVL0 bits to "000
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), all 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 periph-
eral 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 1.8.5 lists the interrupts to exit wait mode.
Rev.1.00 2003.05.30 page 57
clocks are turned off when in wait mode, with the power consumption reduced that
remains on.
C32
Memory expansion mode
Microprocessor mode
Retains status before wait mode
"H"
"H"
"H"
Retains status before wait mode
-
-
Clock Generation Circuit
, f , f
1 2 8
Single-chip mode
-
-
-
-
Retains status before wait mode
Does not stop
•CM02 bit = 0: Does not stop
•CM02 bit = 1: Retains status before
wait mode
______
______
" (interrupts disabled) before executing
2
, f , f , f ,
32 1SIO 8SIO