Controlling Power Using Wait Mode - Renesas M16C Series User Manual

16-bit single-chip microcomputer
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3.9 Controlling Power Using Wait Mode

Overview
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Specifications
Operation
X
OUT
X
CIN
Timer A2 overflow
Timer A2
interrupt processing
INT
0
BCLK
Figure 3.9.1. Operation timing of controling power using wait mode
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
The following are steps for controling power using wait mode. Figure 3.9.1 shows the operation
timing, and Figures 3.9.2 to 3.9.4 show the set-up procedure.
Use the following peripheral functions:
• Timer mode of timer A
• Wait mode
A flag named "F-WIT" is used in the set-up procedure. The purpose of this flag is to decide
whether or not to clear wait mode. If F_WIT = "1" in the main program, the wait mode is entered;
if F_WIT = "0", the wait mode is cleared.
(1) Connect a 32.768-kHz oscillator to X
occur every one second, which is a count the timer reaches, the controller returns from wait
mode and count the clock using a program.
________
(2) Clear wait mode if a INT0 interrupt request occurs.
(1) Switch the system clock from X
(2) Stop X
and enter wait mode. In this instance, enable the timer A2 interrupt and the INT0 interrupt.
IN
(3) When a timer A2 interrupt request occurs (at 1-second intervals), start supplying the BCLK
from X
At this time, count the clock within the routine that handles the timer A2 interrupts
CIN.
and enter wait mode again.
_______
(4) If a INT0 interrupt occurs, start supplying the BCLK from X
_______
the INT0 interrupt, and switch the system clock to X
(1) Shift to low-speed mode
(2) Stop X
"H"
"L"
High-speed
Low-speed
page 325 of 354
to serve as the timer count source. As interrupts
CIN
to X
to get low-speed mode.
IN
CIN
IN
IN
(3) Timer A2 interrupt
Low-speed
3. Controlling Power Applications
_______
. Start the X
oscillation within
CIN
IN
.
(4) INT
interrupt
0
High-speed
Low-speed
Low-speed

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