ISD94100 Series Technical Reference Manual
Sep 9, 2019
Page
526
of 928
Rev1.09
IS
D
9
410
0
S
ER
IE
S
T
E
C
HN
ICA
L
RE
F
E
RE
NCE
M
AN
U
AL
–
Enable WDT peripheral clock in WDTCKEN (CLK_APBCLK0[0]).
–
Force enable WDT controller after chip power-on or reset in CWDTEN[2:0]
(CWDTEN[2] is CONFIG0[31], CWDTEN[1:0] is CONFIG0[4:3])
The WDT clock control are shown in Figure 6.9-2
10
01
HCLK/2048
WDTSEL (CLK_CLKSEL1[1:0])
WDT_CLK
11
10 kHz (LIRC)
32.768 kHz (LXT)
WDTCKEN (CLK_APBCLK0[0])
Figure 6.9-2 Watchdog Timer Clock Control
6.9.5
Functional Description
The WDT includes an 18-bit free running up counter with programmable time-out intervals. Table
6.9.5-1 shows the WDT time-out interval period selection and Figure 6.9-3 shows the WDT time-
out interval and reset period timing.
6.9.5.1
WDT Time-out Interrupt
Setting WDTEN (WDTCR[7]) to 1 will enable the WDT function and the WDT counter to start
counting up. There are eight time-out interval period can be selected by setting TOUTSEL
(WDTCR[10:8]). When the WDT up counter reaches the TOUTSEL (WDTCR[10:8]) settings, WDT
time-out interrupt will occur then WDT time-out interrupt flag IF (WDT_CTL[3]) will be set to 1
immediately. If INTEN (WDT_CTL[6]) is enabled, WDT time-out interrupt will inform to CPU.
6.9.5.2
WDT Reset Delay Period and Reset System
There is a specified T
RSTD
reset delay period follows the IF (WDT_CTL[3]) is setting to 1. User
should set RSTCNT (WDT_CTL[0]) to reset the 18-bit WDT up counter value to avoid generate
WDT time-out reset signal before the T
RSTD
reset delay period expires. Moreover, user should set
RSTDSEL (WDT_ALTCTL [1:0]) to select reset delay period to clear WDT counter. If the WDT up
counter value has not been cleared after the specific T
RSTD
delay period expires, the WDT control
will set RSTF (WDT_CTL[2]) to 1 if RSTEN (WDT_CTL[1]) bit is enabled, then chip enters to reset
state immediately. Refer to , T
RST
reset period will keep last 63 WDT clocks then chip restart
executing program from reset vector (0x0000_0000). The RSTF (WDT_CTL[2]) will keep 1 after
WDT time-out reset the chip, user can check RSTF (WDT_CTL[2]) by software to recognize the
system has been reset by WDT time-out reset or not.
TOUTSEL
Time-Out Interval Period
T
TIS
Reset Delay Period
T
RSTD
000
2
4
* T
WDT
(3/18/130/1026) * T
WDT
001
2
6
* T
WDT
(3/18/130/1026) * T
WDT
010
2
8
* T
WDT
(3/18/130/1026) * T
WDT