PC87393VJG National Semiconductor, PC87393VJG Datasheet - Page 81

• Manufacturer Part Number: PC87393VJG
• Description: IC, SUPER I/O DEVICE, TQFP-100
• Manufacturer: National Semiconductor

Specifications of PC87393VJG

• Data Rate: 2Mbps
• Supply Voltage Range: 3V to 3.6V
• Logic Case Style: TQFP
• No. Of Pins: 100
• Operating Temperature Range: 0°C to +70°C
• Termination Type: SMD
• Transceiver Type: Interface
• Rohs Compliant: No

4.0 WATCHDOG Timer (WDT)
4.3 WATCHDOG TIMER REGISTERS
The WATCHDOG Timer registers at offsets 00h-02h relative to the WATCHDOG base address, are shown in the following
register map. The base address is defined by designated registers in the WATCHDOG Timer device configuration register
set.
The following abbreviations are used to indicate the Register Type:
R/W
R
W
RO
R/W1C = Read/Write 1 to Clear. Writing 1 to a bit clears it to 0. Writing 0 has no effect.
4.3.1
4.3.2
This register holds the programmable timeout period, between 1 and 255 minutes. Writing to this register de-asserts the
WDO output and sets the WDO status bit to 1 (inactive). Additionally, writing to this register is interpreted as a command for
starting or stopping the WATCHDOG Timer, according to the data written. If a non-zero value is written, the timer is activated
(countdown starts). If a non-zero value is written when the counter is running, the timer is immediately reloaded with the new
value and starts counting down from the new value. If 00h is written, the timer and its outputs are de-activated.
Location:
Type:
Bit
Name
Reset
7-0
Bit
WATCHDOG Timer Register Map
WATCHDOG Timeout Register (WDTO)
Programmed Timeout Period. These bits hold the binary value of the timeout period in minutes (1 to 255). A
value of 00h halts the counter and forces the outputs to inactive levels. A device reset clears the register to 00h.
00h: Timer and WDO outputs inactive
01h-FFh: Programmed timeout period (in minutes)
= Read/Write
= Read from a specific address returns the value of a specific register. Write to the same address is to a different register.
= Write
= Read Only
Offset 00h
R/W
Offset Mnemonic
00h
01h
02h
03h
7
0
WDMSK
WDTO
WDST
6
0
(Continued)
WATCHDOG Timeout
WATCHDOG Status
WATCHDOG Mask
5
0
Register Name
Reserved
Programmed Timeout Period
Description
81
4
0
3
0
Type
R/W
R/W
RO
2
0
Section
4.3.2
4.3.3
4.3.4
1
0
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