MB95630H Series
MN702-00009-1v0-E
FUJITSU SEMICONDUCTOR LIMITED
117
CHAPTER 9 WATCH PRESCALER
9.4 Operations and Setting Procedure
Example
•
In sub-CR clock mode
Only the sub-CR clock is used as the input clock of the watch prescaler.
■
Operation Example of Watch Prescaler
Figure 9.4-1 shows an operation example under the following conditions:
1. When a power-on reset occurs
2. When the device transits to the sleep mode during the operation of the interval timer
function in subclock mode or sub-CR clock mode
3. When the device transits to the stop mode during the operation of the interval timer
function in subclock mode or sub-CR clock mode
4. When a request for clearing the counter is issued
The same operation is performed when changing to the watch mode as for when changing to
the sleep mode.
Figure 9.4-1 Watch Prescaler Operation Example
WTIF
b
it
WTIE
b
it
2)
S
LP
b
it
(
S
TBC regi
s
ter)
3
)
S
TP
b
it
(
S
TBC regi
s
ter)
Co
u
nter v
a
l
u
e
(co
u
nt down)
0x0000
O
s
cill
a
tion
s
t
ab
iliz
a
tion w
a
it time
1) Power-on re
s
et
Interv
a
l time
(WPCR:WTC[2:0] = 0
b
011)
0xFFFF
S
leep
S
top
S
leep mode
rele
as
ed
b
y w
a
tch interr
u
pt
S
top mode rele
as
ed
b
y extern
a
l interr
u
pt
• When
s
etting interv
a
l time
s
elect
b
it
s
in the w
a
tch pre
s
c
a
ler control regi
s
ter (WPCR:WTC[2:0]) to "0
b
011" (2
14
×
2/F
CL
)
Co
u
nt v
a
l
u
e detected in
WPCR:WTC[2:0]
4)
• WPCR:WTC[2:0]
• WPCR:WCLR
• WPCR:WTIF
• WPCR:WTIE
•
S
TBC:
S
LP
•
S
TBC:
S
TP
: W
a
tch pre
s
c
a
ler interr
u
pt interv
a
l time
s
elect
b
it
s
in w
a
tch pre
s
c
a
ler control regi
s
ter
: W
a
tch pre
s
c
a
ler cle
a
r
b
it in w
a
tch pre
s
c
a
ler control regi
s
ter
: W
a
tch pre
s
c
a
ler interr
u
pt re
qu
e
s
t fl
a
g
b
it in w
a
tch pre
s
c
a
ler control regi
s
ter
: W
a
tch pre
s
c
a
ler interr
u
pt re
qu
e
s
t en
ab
le
b
it in w
a
tch pre
s
c
a
ler control regi
s
ter
:
S
leep
b
it in
s
t
a
nd
b
y control regi
s
ter
:
S
top
b
it in
s
t
a
nd
b
y control regi
s
ter
Co
u
nter cle
a
red
(WPCR:WCLR = 1)
Cle
a
red
a
t interv
a
l
s
etting
Cle
a
red in interr
u
pt
proce
ss
ing ro
u
tine
Cle
a
red
b
y tr
a
n
s
ition
to
s
top mode
O
s
cill
a
tion
s
t
ab
iliz
a
tion
w
a
it time