R01UH0823EJ0100 Rev.1.00
Page 839 of 1823
Jul 31, 2019
RX23W Group
31. Independent Watchdog Timer (IWDTa)
RPES[1:0] Bits (Window End Position Select)
These bits select 75%, 50%, 25% or 0% of the count period for the window end position of the counter. The window end
position should be a value smaller than the window start position (window start position > window end position). If the
window end position is greater than the window start position, only the window start position setting is enabled.
The counter values for the window start and end positions selected by setting the RPSS[1:0] and RPES[1:0] bits change
depending on the TOPS[1:0] bit setting.
lists the counter values for the window start and end positions corresponding to TOPS[1:0] bit values.
RPSS[1:0] Bits (Window Start Position Select)
These bits select a counter window start position from 100%, 75%, 50%, or 25% of the count period (100% when the
count starts and 0% when the counter underflows). The interval between the window start position and window end
position is the refresh-permitted period and the other periods are refresh-prohibited periods.
shows the relationship between of the RPSS[1:0] and RPES[1:0] bit setting and the refresh-permitted and
refresh-prohibited periods.
Figure 31.2
RPSS[1:0] and RPES[1:0] Bit Settings and the Refresh-Permitted Period
Table 31.3
Relationship between Timeout Period and Window Start and End Counter Values
TOPS[1:0] Bits
Timeout Period
Window Start and End Counter Value
b1
b0
Cycles
Counter Value
100%
75%
50%
25%
0
0
128
007Fh
007Fh
005Fh
003Fh
001Fh
0
1
512
01FFh
01FFh
017Fh
00FFh
007Fh
1
0
1024
03FFh
03FFh
02FFh
01FFh
00FFh
1
1
2048
07FFh
07FFh
05FFh
03FFh
01FFh
Window
Start
(%)
End
1
25
0%
Refresh-permitted period
Underflow
100%
75%
50%
25%
100
75
50
Counting
started
RPSS[1:0] Bits
RPES[1:0] Bits
1
Refresh-prohibited period
(%)
1
1
1
0
0
0
0
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
0
25
50
75
0
25
50
75
0
25
50
75
0
25
50
75
b13
b9
b12
b8
Note:
If window end setting is greater than or equal to window start setting,
the window end setting is set to 0%.