M38203M4 Datasheet, PDF (262/344 Pages) Mitsubishi Electric Semiconductor – 8-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
2.9 Standby function
2.9 Standby function
The 3820 group is provided with a standby function to stop the CPU by software and put the CPU into the
low-power operation.
The following two types of standby function are available.
•Stop mode by the STP instruction
•Wait mode by the WIT instruction
2.9.1 Stop mode
The stop mode is set by executing the STP instruc-
tion. In the stop mode, the oscillation of both XIN
and XCIN stops and the internal clock φ stops at the
“H” level.
The CPU stops and peripheral units stop operating.
As a result, power dissipation is reduced.
(1) State in the stop mode
The stop mode is set by executing the STP
instruction.^V1
In the stop mode, the oscillation of both XIN
and XCIN stops, so that all the functions stop,
providing a low-power operation.
Table 2.9.1 shows the state in the stop mode.
Table 2.9.1 State in stop mode
Item
State in stop mode
Oscillation
CPU
Stop
Stop
Internal clock φ
Stop at “H” level
I/O ports P0–P7
The state where STP in-
struction is executed is held
Timer, serial I/O,
Stop
LCD display functions,
watchdog timer
V1: After setting the LCD enable bit (bit 3) of
the LCD mode register to “0,” execute the
STP instruction.
2–176
3820 GROUP USER’S MANUAL