M16C62_M Datasheet, PDF (529/615 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

Controlling Power Applications
Mitsubishi microcomputers
M16C / 62A Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
3.7 Controlling Power Using Stop Mode
Overview
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
Specifications
_____
(1) Use P100 through P103 for the scan output pins of a key matrix. Use the input pins (KI0
_____
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.
Operation
_____
_____
(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.
_____
_____
(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.
(1) Shift to stop mode
(2) Cancel a stop mode
(3) Key scan
(4) Shift to stop mode
Key matrix scan
P100 output
P101 output
P102 output
P103 output
P104 to P107 input
Key input
Key input
interrupt processing
CPU clock
Key OFF
Key ON
Key OFF
Key ON
Stop mode
Stop mode
Figure 3.7.1. Operation timing of controlling power using stop mode
2-212