sh66p51 SinoWealth Micro-Electronics Corp. Ltd, sh66p51 Datasheet - Page 31

• Manufacturer Part Number: sh66p51
• Description: Otp 2k 4-bit Micro-controller With Lcd Driver
• Manufacturer: SinoWealth Micro-Electronics Corp. Ltd

14. Watchdog Timer
Watchdog timer is a down-count counter, and its clock source is OSC clock (32.768kHz Crystal or 131kHZ RC) and will not
run in the STOP mode. The watchdog timer automatically generates a device reset when it overflows. It can be enabled or
disabled permanently by using the Code Option.
The watchdog timer control bits ($1E bit2 - bit0) are used to select different overflow frequency. The watchdog timer
overflow flag ($1E bit3) will be automatically set to “1” by hardware when the watchdog timer overflows. And the flag ($1E
bit3) will be clear to “0” when read $1E. By reading or writing the system register $1E, the watchdog timer should re-count
before the overflow happens.
System Register $1E: Watchdog Timer (WDT)
Note:
Watchdog timer overflow period is valid for V
15. Warm-up Timer
The device has a built-in warm-up timer to eliminate unstable state of initial oscillation when oscillator starts oscillating in the
following conditions:
- Power-on Reset/Low voltage Reset/Pin Reset warm-up time interval:
- Wake-up from stop mode
- Watchdog Reset
(1) In RC oscillator mode, the warm-up counter prescaler divide ratio is /2
(2) In internal 4M RC oscillator mode, the warm-up counter prescaler divide ratio is /2
(3) In Crystal oscillator or Ceramic resonator mode, the warm-up counter prescaler divide ratio is /2
16. Code Option
OSC: (Code Option)
- 0: Crystal oscillator 32.768kHz Crystal
- 1: RC oscillator: 131kHz RC
WDT: (Code Option)
- 0: Enable the watchdog timer
- 1: Disable the watchdog timer
Reset internal pull-high resistor: (Code Option)
- 0: Enable
- 1: Disable
Address
$1E
WDT
Bit 3
X
X
X
X
X
X
X
X
0
1
WDT.2
Bit 2
X
X
0
0
0
0
1
1
1
1
WDT.1
Bit 1
X
X
0
0
1
1
0
0
1
1
WDT.0
Bit 0
DD
X
X
0
1
0
1
0
1
0
1
= 3V.
R/W
R/W
R
Bit0 - 2: Watchdog timer control
Bit3: Watchdog timer overflow flag. (Read only)
Watchdog timer-out period = 2
Watchdog timer-out period = 2
Watchdog timer-out period = 2
Watchdog timer-out period = 2
Watchdog timer-out period = 2
Watchdog timer-out period = 2
Watchdog timer-out period = 2
Watchdog timer-out period = 2
No watchdog timer overflow reset
Watchdog timer overflow
31
10
(1024).
Remarks
15
(32768).
17
15
13
11
10
9
8
7
/f
/f
/f
/f
/f
/f
/f
/f
OSC
OSC
OSC
OSC
OSC
OSC
OSC
OSC
13
(8192).
SH66P51
Power ON
0000
Yes
Yes