R01UH0823EJ0100 Rev.1.00
Page 822 of 1823
Jul 31, 2019
RX23W Group
30. Watchdog Timer (WDTA)
30.2.2
WDT Control Register (WDTCR)
There are some restrictions on writing to the WDTCR register. For details, refer to
Writing to the WDTCR and WDTRCR Registers
.
In auto-start mode, the settings in the WDTCR register are disabled, and the settings in option function select register 0
(OFS0) are enabled. The bit setting made to the WDTCR register can also be made in OFS0 register. For details, refer to
section 30.3.7, Correspondence between Option Function Select Register 0 (OFS0) and WDT Registers
TOPS[1:0] Bits (Timeout Period Selection)
These bits select the timeout period (period until the down-counter underflows) from among 1024, 4096, 8192, and
16384 cycles, taking the divided clock specified by the CKS[3:0] bits as one cycle.
After the down-counter is refreshed, the combination of the CKS[3:0] and TOPS[1:0] bits determines the time (number
of PCLK cycles) until the counter underflows.
Relations between the CKS[3:0] and TOPS[1:0] bit settings, the timeout period, and the number of PCLK cycles are
listed in
Address(es): 0008 8022h
b15
b14
b13
b12
b11
b10
b9
b8
b7
b6
b5
b4
b3
b2
b1
b0
—
—
RPSS[1:0]
—
—
RPES[1:0]
CKS[3:0]
—
—
TOPS[1:0]
Value after reset:
0
0
1
1
0
0
1
1
1
1
1
1
0
0
1
1
Bit
Symbol
Bit Name
Description
R/W
b1, b0
Timeout Period Selection
b1 b0
0 0: 1024 cycles (03FFh)
0 1: 4096 cycles (0FFFh)
1 0: 8192 cycles (1FFFh)
1 1: 16384 cycles (3FFFh)
R/W
b3, b2
—
Reserved
These bits are read as 0 and cannot be modified.
R
b7 to b4
Clock Division Ratio Selection
b7 b4
0 0 0 1: Divide-by-4
0 1 0 0: Divide-by-64
1 1 1 1: Divide-by-128
0 1 1 0: Divide-by-512
0 1 1 1: Divide-by-2048
1 0 0 0: Divide-by-8192
Setting other than above are prohibited.
R/W
b9, b8
Window End Position Selection
b9 b8
0 0: 75%
0 1: 50%
1 0: 25%
1 1: 0% (window end position is not specified)
R/W
b11, b10
—
Reserved
These bits are read as 0 and cannot be modified.
R
b13, b12
Window Start Position Selection
b13 b12
0 0: 25%
0 1: 50%
1 0: 75%
1 1: 100% (window start position is not specified)
R/W
b15, b14
—
Reserved
These bits are read as 0 and cannot be modified.
R