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Rev. 1.00
54
October 26, 2018
Rev. 1.00
55
October 26, 2018
BS86DH12C
High Voltage Touch A/D Flash MCU with HVIO
BS86DH12C
High Voltage Touch A/D Flash MCU with HVIO
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 clock, f
LIRC
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
18
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 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 control
10101 or 01010: Enable
Other values: Reset MCU
When these bits are changed to any other values due to environmental noise the
microcontroller will be reset; this reset operation will be activated after a delay time,
t
SRESET
, and the WRF bit in the RSTFC register will be set high.
Bit 2~0
WS2~WS0
: WDT time-out period selection
000: 2
8
/f
LIRC
001: 2
10
/f
LIRC
010: 2
12
/f
LIRC
011: 2
14
/f
LIRC
100: 2
15
/f
LIRC
101: 2
16
/f
LIRC
110: 2
17
/f
LIRC
111: 2
18
/f
LIRC
These three bits determine the division ratio of the Watchdog Timer source clock,
which in turn determines the time-out period.
• RSTFC Register
Bit
7
6
5
4
3
2
1
0
Name
—
—
—
—
RSTF
LVRF
LRF
WRF
R/W
—
—
—
—
R/W
R/W
R/W
R/W
POR
—
—
—
—
0
x
0
0
“x”: unknown
Bit 7~4
Unimplemented, read as “0”
Bit 3
RSTF
: Reset control register software reset flag
Described elsewhere
Bit 2
LVRF
: LVR function reset flag
Described elsewhere