Fujitsu FR81S User Manual
CHAPTER 30: POWER CONSUMPTION CONTROL
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : POWER CONSUMPTION CONTROL
FUJITSU SEMICONDUCTOR CONFIDENTIAL
29
5.4.2. Activation of Watch Mode
Activation of watch mode is described below.
To activate watch mode, follow the steps below.
·"0" is written in bit7:SHDE of the PMUCTLR register.
·When performing PLL RUN, CPU must go into main RUN state first. (When performing sub RUN state, it
transits directly to watch mode.)
·Write "010" to bit7:STOP, bit6:TIMER, bit5:SLEEP in the STBCR register.
·Read the STBCR register.
In FR81S core, if the read value will not be used in the next instruction, that instruction is executed before
the read is completed. Perform dummy processing to use the read value in the next instruction so as not to
make the program progress before entering watch mode.
[Example] Sample program of watch mode activation
LDI
#value_of_timer, R0
;TIMER bit ="1", SLVL setting
LDI
#_STBCR, R12
;
STB
R0, @R12
; Write
LDUB @R12, R0
; Read (activation of watch mode)
MOV
R0, R0
; Dummy processing for pipeline adjustment
NOP
; Dummy processing for pipeline adjustment
MB91520 Series
MN705-00010-1v0-E
1116