PIC18F6621-I/PT Microchip Technology Inc., PIC18F6621-I/PT Datasheet - Page 269

• Manufacturer Part Number: PIC18F6621-I/PT
• Description: 64 PIN, 64 KB FLASH, 3840 RAM, 52 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F6621-I/PT

• A/d Inputs: 12-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 10 MIPS
• Eeprom Memory: 1024 Bytes
• Input Output: 54
• Interface: I2C/SPI/UART/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 64-pin TQFP
• Programmable Memory: 64K Bytes
• Ram Size: 3.8K Bytes
• Speed: 40 MHz
• Timers: 2-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

24.2
The Watchdog Timer is a free running on-chip RC
oscillator which does not require any external
components. This RC oscillator is separate from the
RC oscillator of the OSC1/CLKI pin. That means that
the WDT will run even if the clock on the OSC1/CLKI
and OSC2/CLKO/RA6 pins of the device has been
stopped, for example, by execution of a SLEEP
instruction.
During normal operation, a WDT time-out generates a
device Reset (Watchdog Timer Reset). If the device is
in Sleep mode, a WDT time-out causes the device to
wake-up and continue with normal operation (Watch-
dog Timer wake-up). The TO bit in the RCON register
will be cleared upon a WDT time-out.
The Watchdog Timer is enabled or disabled by a device
configuration bit, WDTEN (CONFIG2H<0>). If WDTEN
is set, software execution may not disable this function.
When WDTEN is cleared, the SWDTEN bit enables or
disables the operation of the WDT.
REGISTER 24-15: WDTCON: WATCHDOG TIMER CONTROL REGISTER
 2005 Microchip Technology Inc.
Watchdog Timer (WDT)
bit 7-1
bit 0
bit 7
Unimplemented: Read as ‘0’
SWDTEN: Software Controlled Watchdog Timer Enable bit
1 = Watchdog Timer is on
0 = Watchdog Timer is turned off (if CONFIG2H<0> = 0)
Legend:
R = Readable bit
-n = Value at POR
U-0
—
U-0
—
PIC18F6525/6621/8525/8621
U-0
—
W = Writable bit
‘1’ = Bit is set
U-0
The WDT time-out period values may be found in the
Electrical Specifications section under parameter 31.
Values for the WDT postscaler may be assigned using
the configuration bits.
24.2.1
Register 24-15 shows the WDTCON register. This is a
readable and writable register which contains a control
bit that allows software to override the WDT enable
configuration bit only when the configuration bit has
disabled the WDT.
—
Note 1: The CLRWDT and SLEEP instructions
2: When a CLRWDT instruction is executed
CONTROL REGISTER
U-0
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
clear the WDT and the postscaler if
assigned to the WDT and prevent it from
timing out and generating a device Reset
condition.
and the postscaler is assigned to the
WDT, the postscaler count will be cleared
but the postscaler assignment is not
changed.
—
U-0
—
x = Bit is unknown
U-0
—
DS39612B-page 267
SWDTEN
R/W-0
bit 0