17 WATCHDOG TIMER (WDT)
17-6
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
WDT Comparison Data L/H Registers (WD_CMP_L, WD_CMP_H)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
WDT
Comparison
Data L Register
(WD_CMP_L)
0x301004
(16 bits)
D15–0 CMPDT
[15:0]
WDT comparison data
CMPDT0 = LSB
0x0 to 0x3fffffff
(low-order 16 bits)
0x0 R/W Write-protected
WDT
Comparison
Data H Register
(WD_CMP_H)
0x301006
(16 bits)
D15–14 –
reserved
–
–
–
0 when being read.
D13-0 CMPDT
[29:16]
WDT comparison data
CMPDT29 = MSB
0x0 to 0x3fffffff
(high-order 14 bits)
0x0 R/W Write-protected
Note: These registers are write-protected to prevent NMI or reset signals from being inadvertently
generated by unnecessary write operations. To rewrite these registers, write protection must be
removed by writing 0x96 to WDPTC[15:0]/WD_PROTECT register. Once the registers have been
rewritten, be sure to write other than 0x96 to WDPTC[15:0] to reapply write protection.
D[13:0]/0x301006, D[15:0]/0x301004
CMPDT[29:0]: WDT Comparison Data Bits
Sets comparison data. (Default: 0x0)
Use these registers to set the NMI/reset generation cycle.
With NMI or reset generation enabled, an NMI or reset signal is output when the up-counter matches
the comparison data set in these registers.
When a clock is output from the watchdog timer, these registers also set the output clock cycle.
Note: Do not set a value equal to or less than 0x1f as comparison data.
WDT Count Data L/H Registers (WD_CNT_L, WD_CNT_H)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
WDT Count
Data L Register
(WD_CNT_L)
0x301008
(16 bits)
D15–0 CTRDT
[15:0]
WDT counter data
CTRDT0 = LSB
0x0 to 0x3fffffff
(low-order 16 bits)
X
R
WDT Count
Data H Register
(WD_CNT_H)
0x30100a
(16 bits)
D15–14 –
reserved
–
–
–
0 when being read.
D13-0 CTRDT
[29:16]
WDT counter data
CTRDT29 = MSB
0x0 to 0x3fffffff
(high-order 14 bits)
X
R
D[13:0]/0x30100a, D[15:0]/0x301008
CTRDT[29:0]: WDT Counter Data Bits
The current count value of the 30-bit up-counter can be read out from these registers.
(Default: indeterminate)
WDT Control Register (WD_CTL)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
WDT Control
Register
(WD_CTL)
0x30100c
(16 bits)
D15–1 –
reserved
–
–
–
0 when being read.
D0
WDRESEN WDT reset
1 Reset
0 ignored
0
W
D[15:1] Reserved
D0
WDRESEN: WDT Reset Bit
This bit resets the watchdog timer.
1 (W):
Reset
0 (W):
Has no effect
0 (R):
Always 0 when read (default)
With NMI or reset signal output enabled, the watchdog timer must be reset by writing 1 to this bit with-
in the set NMI/reset generation cycle. The up-counter is thereby reset to 0, then starts counting NMI/
reset generation cycles all over again.