17 WATCHDOG TIMER (WDT)
S1C33L26 TECHNICAL MANUAL
Seiko Epson Corporation
17-5
WDT Enable and Setup Register (WD_EN)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
WDT Enable
and Setup
Register
(WD_EN)
0x301002
(16 bits)
D15–7 –
reserved
–
–
–
0 when being read.
D6
CLKSEL
WDT input clock select
1 External clk 0 Internal clk
0
R/W Write-protected
D5
CLKEN
WDT clock output control
1 On
0 Off
0
R/W
D4
RUNSTP
WDT Run/Stop control
1 Run
0 Stop
0
R/W
D3–2 –
reserved
–
–
–
0 when being read.
D1
NMIEN
WDT NMI enable
1 Enable
0 Disable
0
R/W Write-protected
D0
RESEN
WDT RESET enable
1 Enable
0 Disable
0
R/W
Note: This register is write-protected to prevent NMI or reset signals from being inadvertently generated
by unnecessary write operations. To rewrite this register, write protection must be removed by
writing 0x96 to WDPTC[15:0]/WD_PROTECT register. Once the register has been rewritten, be
sure to write other than 0x96 to WDPTC[15:0] to reapply write protection.
D[15:7] Reserved
D6
CLKSEL: WDT Input Clock Select Bit
This bit selects the count clock for the watchdog timer.
1 (R/W): External clock (T16A_EXCL_0)
0 (R/W): Internal clock (PCLK2) (default)
Setting this bit to 0 (default) selects the internal clock (PCLK2); setting it to 1 selects the external clock
(T16A_EXCL_0).
D5
CLKEN: WDT Clock Output Control Bit
This bit controls the clock output of the watchdog timer.
1 (R/W): On
0 (R/W): Off (default)
Setting this bit to 1 outputs an NMI/reset generation cycle-synchronous clock from the IC.
D4
RUNSTP: WDT Run/Stop Control Bit
This bit starts or stops the watchdog timer.
1 (R/W): Start
0 (R/W): Stop (default)
When the NMI or reset generation function is enabled, be sure to set comparison data and reset the
watchdog timer before starting the watchdog timer, thus preventing the generation of unnecessary NMI
or reset signals.
D[3:2]
Reserved
D1
NMIEN: WDT NMI Enable Bit
This bit enables NMI signal output by the watchdog timer.
1 (R/W): Enable
0 (R/W): Disable (default)
Setting this bit to 1 outputs an NMI signal (a pulse 32 system clocks in width) to the CMU and the
#WDT_NMI pin when the count of the up-counter matches the value set in the comparison data regis-
ter. Setting this bit to 0 outputs no NMI signals.
Regardless of how this bit is set, the up-counter is reset to 0 when the up-counter and set value of the
comparison data register match, then starts counting all over again.
D0
RESEN: WDT RESET Enable Bit
This bit enables internal reset signal output by the watchdog timer.
1 (R/W): Enable
0 (R/W): Disable (default)
Setting this bit to 1 outputs a reset signal (a pulse 32 system clocks in width) to the CMU when the
count of the up-counter matches the value set in the comparison data register. Setting this bit to 0 out-
puts no reset signals.