Watchdog Timer Control Register (Wdtc) - Fujitsu F2MC-16LX Hardware Manual

CHAPTER 10 WATCHDOG TIMER

10.2 Watchdog Timer Control Register (WDTC)

The watchdog timer control register (WDTC) is used for the start and clearing of the
watchdog timer and the display of reset causes.
I Watchdog timer control register (WDTC)
Figure 10.2-1 "Watchdog timer control register (WDTC)" shows the configuration of the
watchdog timer control register (WDTC), and Table 10.2-1 "Function of bits in watchdog timer
control register (WDTC)" explains the function of each bit in the WDTC register.
Address
0000A8
H
R : Read only
W : Write only
x : Undefined
- : Not used
* : The previous state is held.
: Default value
The interval time is 3.5 to 4.5 times as large as the count clock (output of the timebase timer)
cycle. See Section 10.4 "Watchdog Timer Operation", for details.
206
Figure 10.2-1 Watchdog timer control register (WDTC)
bit15 bit8 bit7 bit6
(TBTC) PONR Reserved
R
Interval time selection bit (at HCLK: 4 MHz; SCLK: 32 kHz)
WT1 WT0
WDCS
& SCM
0 0
1 Approximately 3.58 ms
0 1 Approximately 14.33 ms Approximately 18.3 ms
1 1
1 Approximately 57.23 ms Approximately 73.73 ms
1 1 1 Approximately 458.75 ms Approximately 589.82 ms
0 0 0 Approximately 0.457 s
1 0
0 Approximately 3.584 s
0
1 0 Approximately 7.168 s
1 1
0 Approximately 14.336 s
HCLK: Oscillation clock
SCLK: Sub-clock
WTE
Starts the watchdog timer
(at first write event after reset)
0
Clears the watchdog timer
(at second write event after reset)
1 No operation
Reserved bit Reading and writing has no effect on operation
Reset cause bits
PONR WRST ERST SRST
1 X
* 1
* *
* *
bit5 bit4 bit3 bit2 bit1
WRST ERST SRST WTE WT1 WT0
R R R W W
Interval time
Minimum Maximum
Approximately 4.61 ms
Approximately 0.576 s
Approximately 4.608 s
Approximately 9.216 s
Approximately 18.432 s
Watchdog control bit
Reset cause
X X Power on
* * Watchdog timer
1 * External pin (RST = "L" input)
* 1 RST bit (software reset)
bit0 Initial value
XXXXX111
B
W
Number of oscillation
clock cycles
14 ± 2 11
2 HCLK cycles
16 ± 2 13
2 HCLK cycles
18 ± 2 15
2 HCLK cycles
21 ± 2 18
2 HCLK cycles
12 ± 2 9
2 SCLK cycles
15 ± 2 12
2 SCLK cycles
± 2
17 13
2 SCLK cycles
17 ± 2 14
2 SCLK cycles