
iVPeRiPheRaLMoDuLes2(tiMeRs):WatChDogtiMeR(WDt)
s1C33L17teChniCaLManuaL
ePson
iV-2-9
IV
WDT
0300662:WatchdogtimerenableRegister(pWD_en)
name
address
Registername
bit
Function
setting
init. R/W
Remarks
–
–
CLKseL
CLKen
RunstP
–
nMien
Resen
D15–7
D6
D5
D4
D3–2
D1
D0
reserved
Watchdogtimerinputclockselect
Watchdogtimerclockoutputcontrol
WatchdogtimerRun/Stopcontrol
reserved
WatchdogtimerNMIenable
WatchdogtimerRESETenable
–
0
–
0
–
R/W
–
R/W
0whenbeingread.
00300662
(hW)
1 Enabled
0 Disabled
Watchdog
timerenable
register
(pWD_EN)
1 Enabled
0 Disabled
1 Run
0 Stop
1 On
0 Off
1 Externalclock 0 Internalclock
note: This register is write-protected to prevent NMI or reset signals from being inadvertently gener-
atedbyunnecessarywriteoperations.Torewritethisregister,writeprotectionmustberemoved
bywriting0x96totheWatchdogTimerWrite-ProtectRegister(0x300660).Oncetheregisterhas
been rewritten, be sure to write other than 0x96 to theWatchdogTimerWrite-Protect Register
(0x300660)toreapplywriteprotection.
D[15:7] Reserved
D6
CLKseL:WatchdogtimerinputClockselectbit
This bit selects the count clock for the watchdog timer.
1 (R/W): External clock (EXCL0)
0 (R/W): Internal clock (MCLK) (default)
Setting this bit to 0 (default) selects the internal clock (MCLK); setting it to 1 selects the external clock
(EXCL0). Before an external clock can be used, the function of the pin set by default as an I/O port
must be switched to EXCL0 (external clock input for 16-bit timer 0) by using the Port Function Select
Register. For details about pin functions and how to switch over, see Section I.3.3, “Switching Over the
Multiplexed Pin Functions.”
D5
CLKen:WatchdogtimerClockoutputControlbit
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. Before this
clock output can be used, however, the function of the pin set by default as an I/O port must be switched
to WDT_CLK (watchdog timer clock output) by using the Port Function Select Register. For details
about pin functions and how to switch over, see Section I.3.3, “Switching Over the Multiplexed Pin
Functions.”
D4
RunstP:WatchdogtimerRun/stopControlbit
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