Rev. 1.10
44
November 04, 2019
Rev. 1.10
45
November 04, 2019
HT45F5Q-3
Battery Charger Flash MCU
HT45F5Q-3
Battery Charger Flash MCU
Watchdog Timer
The Watchdog Timer is provided to prevent program malfunctions or sequences from jumping to
unknown locations, due to certain uncontrollable external events such as electrical noise.
Watchdog Timer Clock Source
The Watchdog Timer clock source is provided by the internal f
LIRC
clock which is sourced from
the LIRC oscillator. The LIRC internal oscillator has an approximate frequency of 32kHz and this
specified internal clock period can vary with V
DD
, temperature and process variations. The Watchdog
Timer source clock is then subdivided by a ratio of 2
8
to 2
1
5
to give longer timeouts, the actual value
being chosen using the WS2~WS0 bits in the WDTC register.
Watchdog Timer Control Register
A single register, WDTC, controls the required time-out period as well as the enable/disable and reset
MCU operation.
• WDTC Register
Bit
7
6
5
4
3
2
1
0
Name
WE4
WE3
WE2
WE1
WE0
WS2
WS1
WS0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
0
1
0
1
0
0
1
1
Bit 7~3
WE4~WE0
: WDT function software control
10101: Disable
01010: Enable
Other values: Reset MCU
When these bits are changed to any other values by the environmental noise to reset
the microcontroller, the reset operation will be activated after a delay
time, t
SRESET
,
and the WRF bit in the RSTFC register will be set to 1 to indicate the reset source.
Bit 2~0
WS2~WS0
: WDT time-out period selection
000: 2
8
/f
LIRC
001: 2
9
/f
LIRC
010: 2
1
0
/f
LIRC
011: 2
11
/f
LIRC
100: 2
1
2
/f
LIRC
101: 2
13
/f
LIRC
110: 2
14
/f
LIRC
111: 2
1
5
/f
LIRC
These three bits determine the division ratio of the Watchdog Timer source clock,
which in turn determines the timeout period.
• RSTFC Register
Bit
7
6
5
4
3
2
1
0
Name
—
—
—
—
—
LVRF
LRF
WRF
R/W
—
—
—
—
—
R/W
R/W
R/W
POR
—
—
—
—
—
x
0
0
“x”: unknown
Bit 7~3
Unimplemented, read as “0”
Bit 2
LVRF
: LVR function reset flag
Described elsewhere
Bit 1
LRF
: LVR control register software reset flag
Described elsewhere