R01UH0823EJ0100 Rev.1.00
Page 151 of 1823
Jul 31, 2019
RX23W Group
7. Option-Setting Memory (OFSM)
counted by the counter. The value of the window end position must be smaller than the value of the window start position
(window start position > window end position). If the value for the window end position is greater than the value for the
window start position, only the value for the window start position is effective.
The counter values corresponding to the settings for the start and end positions of the window in the IWDTRPSS[1:0]
and IWDTRPES[1:0] bits vary with the setting of the IWDTTOPS[1:0] bits.
For details, refer to
section 31, Independent Watchdog Timer (IWDTa)
IWDTRPSS[1:0] Bits (IWDT Window Start Position Select)
These bits select the position where the window for the down-counter starts as 25%, 50%, 75%, or 100% of the value
being counted (the point at which counting starts is 100% and the point at which an underflow occurs is 0%). The
interval between the positions where the window starts and ends becomes the period in which refreshing is possible, and
refreshing is not possible outside this period.
For details, refer to
section 31, Independent Watchdog Timer (IWDTa)
IWDTRSTIRQS Bit (IWDT Reset Interrupt Request Select)
The setting of this bit selects the operation on an underflow of the down-counter or generation of a refresh error. Either
an independent watchdog timer reset or a non-maskable interrupt request is selectable.
For details, refer to
section 31, Independent Watchdog Timer (IWDTa)
IWDTSLCSTP Bit (IWDT Sleep Mode Count Stop Control)
This bit selects whether to stop counting when entering sleep, software standby, or deep sleep mode.
For details, see
section 31, Independent Watchdog Timer (IWDTa)
WDTSTRT Bit (WDT Start Mode Select)
This bit selects the mode in which the WDT is activated after a reset (stopped state or activated in auto-start mode).
When activated in auto-start mode, the OFS0 register setting for the WDT is effective.
WDTTOPS[1:0] Bits (WDT Timeout Period Select)
These bits select the timeout period, i.e. the time it takes for the down-counter to underflow, as 1024, 4096, 8192, or
16384 cycles of the frequency-divided clock set by the WDTCKS[3:0] bits. The time (number of PCLKB cycles) it takes
to underflow after a refresh operation is determined by a combination of the WDTCKS[3:0] bits and WDTTOPS[1:0]
bits.
For details, see
section 30, Watchdog Timer (WDTA)
WDTCKS[3:0] Bits (WDT Clock Frequency Division Ratio Select)
These bits select, from 1/4, 1/64, 1/128, 1/512, 1/2048, and 1/8192, the division ratio of the prescaler to divide the
frequency of PCLKB. Using the setting of these bits together with the WDTTOPS[1:0] bit setting, the WDT counting
period can be set from 4096 to 134217728 PCLKB cycles.
For details, see
section 30, Watchdog Timer (WDTA)
WDTRPES[1:0] Bits (WDT Window End Position Select)
These bits select the position of the end of the window on the down-counter as 0%, 25%, 50%, or 75% of the value being
counted by the counter. The value of the window end position must be smaller than the value of the window start position
(window start position > window end position). If the value for the window end position is greater than the value for the
window start position, only the value for the window start position is effective.
The counter values corresponding to the settings for the start and end positions of the window in the WDTRPSS[1:0] and
WDTRPES[1:0] bits vary with the setting of the WDTTOPS[1:0] bits.
For details, refer to
section 30, Watchdog Timer (WDTA)
.