PIC18F2539-I/SP Microchip Technology, PIC18F2539-I/SP Datasheet - Page 205

• Manufacturer Part Number: PIC18F2539-I/SP
• Description: IC MCU FLASH 12KX16 EE A/D 28DIP
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F2539-I/SP

• Core Size: 8-Bit
• Program Memory Size: 24KB (12K x 16)
• Core Processor: PIC
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, POR, PWM, WDT
• Number Of I /o: 21
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 1408 x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 5x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-DIP (0.300", 7.62mm)
• Controller Family/series: PIC18
• No. Of I/o's: 21
• Eeprom Memory Size: 256Byte
• Ram Memory Size: 1.375KB
• Cpu Speed: 40MHz
• No. Of Timers: 4
• Processor Series: PIC18F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 1408 B
• Interface Type: I2C, SPI, AUSART
• Maximum Clock Frequency: 40 MHz
• Number Of Programmable I/os: 21
• Number Of Timers: 3
• Operating Supply Voltage: 2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734, 52712-325, EWPIC18
• Development Tools By Supplier: DV164005, DV164136
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 5 Channel
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With: DVA18XP280 - DEVICE ADAPTER 18F2220 PDIP 28LD
• Lead Free Status / Rohs Status: Details

20.2
The Watchdog Timer is a free running on-chip RC
oscillator, which does not require any external compo-
nents. 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/disabled by a device
configuration bit. If the WDT is enabled, software exe-
cution may not disable this function. When the WDTEN
configuration bit is cleared, the SWDTEN bit enables/
disables the operation of the WDT.
REGISTER 20-13: WDTCON REGISTER
 2002 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 the WDTEN configuration bit in the
Legend:
R = Readable bit
U = Unimplemented bit, read as ‘0’
U-0
—
configuration register = 0
U-0
—
U-0
Preliminary
—
U-0
—
The WDT time-out period values may be found in the
Electrical Specifications (Section 23.0) under parame-
ter D031. Values for the WDT postscaler may be
assigned using the configuration bits.
20.2.1
Register 20-13 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
W = Writable bit
- n = Value at POR
2: When a CLRWDT instruction is executed
U-0
—
CONTROL REGISTER
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.
PIC18FXX39
U-0
—
U-0
—
DS30485A-page 203
SWDTEN
R/W-0
bit 0