BS85B12-3 HOLTEK [Holtek Semiconductor Inc], BS85B12-3 Datasheet - Page 47

• Manufacturer Part Number: BS85B12-3
• Description: Touch Key Flash Type 8-Bit MCU with LCD/LED Driver
• Manufacturer: HOLTEK [Holtek Semiconductor Inc]

BS85B12-3/BS85C20-3
Touch Key Flash MCU with LCD/LED Driver
Watchdog Timer
Rev. 1.00
Bit 7
Bit 6~4
Bit 3~0
Name
POR
R/W
Watchdog Timer Clock Source
Watchdog Timer Control Register
Bit
WDTC Register
FSYSON
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.
The Watchdog Timer clock source is provided by the internal low speed oscillator, f
Timer source clock is then subdivided by a ratio of 2
being chosen using the WS2~WS0 bits in the WDTC register. The LIRC internal oscillator has an
approximate period of 32kHz at a supply voltage of 5V.
However, it should be noted that this specified internal clock period can vary with VDD, temperature
and process variations.
A single register, WDTC, controls the required timeout period.
R/W
FSYSON: f
WS2, WS1, WS0 : WDT time-out period selection
These three bits determine the division ratio of the Watchdog Timer source clock, which in turn
determines the timeout period.
Undefined bit
These bits can be read or written by user software program.
7
0
0: disable
1: enable
000: 256/f
001: 512/f
010: 1024/f
011: 2048/f
100: 4096/f
101: 8192/f
110: 16384/f
111: 32768/f
SYS
LIRC
LIRC
WS2
R/W
LIRC
LIRC
LIRC
LIRC
6
1
LIRC
LIRC
control in IDLE Mode
WS1
R/W
5
1
WS0
R/W
41
4
1
R/W
8
D3
to 2
3
1
15
to give longer timeouts, the actual value
R/W
D2
2
0
R/W
D1
1
1
LIRC
February 1, 2011
. The Watchdog
R/W
D0
0
0