
Controlling Power Applications
Mitsubishi microcomputers
M16C / 62A Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
2-212
3.7 Controlling Power Using Stop Mode
The following are steps for controlling power using stop mode. Figure 3.7.1 shows the operation
timing, Figure 3.7.2 shows an example of circuit, and Figures 3.7.3 and 3.7.4 show the set-up
procedure.
Use the following peripheral functions:
Key-input interrupts
Stop mode
Pull-up function
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(1) Use P100 through P103 for the scan output pins of a key matrix. Use the input pins (KI0
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through KI3) of the key-input interrupt function for the key-input reading pins. The pull-up
function is also used.
(2) If a key-input interrupt request occurs, clear the stop mode and read a key.
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(1) Enable a key-input interrupt and set the pull-up function to pins KI0 through KI3. Change the
output of P100 through P103 to “L” and enter stop mode.
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(2) If a key is pressed, “L” is input to one of pins KI0 through KI3 to clear stop mode. A key-input
interrupt occurs to execute the key-input interrupt handling routine.
(3) Sequentially set P100 through P103 to “L” to determine which key was pressed.
(4) When the process to determine the key pressed is completed, change the output from P100
through P103 to “L” again and enter stop mode.
Figure 3.7.1. Operation timing of controlling power using stop mode
P100 output
P101 output
P102 output
P103 output
P104 to P107 input
Key input
Key OFF
Key ON
Stop mode
Key input
interrupt processing
CPU clock
Stop mode
Key matrix scan
(1) Shift to stop mode
(2) Cancel a stop mode
(3) Key scan
(4) Shift to stop mode
Key ON
Overview
Specifications
Operation