MA180025 Microchip Technology, MA180025 Datasheet - Page 331

• Manufacturer Part Number: MA180025
• Description: MODULE PLUG-IN PIC18F87J90 PIM
• Manufacturer: Microchip Technology
• Series: PIC®r

Specifications of MA180025

• Accessory Type: Plug-In Module (PIM) - PIC18F87J90
• Product: Microcontroller Modules
• Silicon Manufacturer: Microchip
• Core Architecture: PIC
• Core Sub-architecture: PIC18
• Silicon Core Number: PIC18F
• Silicon Family Name: PIC18FxxJxx
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: PICDEM LCD 2 Demonstration Board (DM163030)
• For Use With: DM163030 - KIT DEV PICDEM LCD2
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

25.2
For PIC18F87J90 family devices, the WDT is driven by
the INTRC oscillator. When the WDT is enabled, the
clock source is also enabled. The nominal WDT period is
4 ms and has the same stability as the INTRC oscillator.
The 4 ms period of the WDT is multiplied by a 16-bit
postscaler. Any output of the WDT postscaler is
selected by a multiplexor, controlled by the WDTPS bits
in Configuration Register 2H. Available periods range
from 4 ms to 131.072 seconds (2.18 minutes). The
WDT and postscaler are cleared whenever a SLEEP or
CLRWDT instruction is executed, or a clock failure
(primary or Timer1 oscillator) has occurred.
FIGURE 25-1:
 2010 Microchip Technology Inc.
All Device Resets
INTRC Oscillator
WDTPS<3:0>
Watchdog Timer (WDT)
SWDTEN
CLRWDT
Sleep
WDT BLOCK DIAGRAM
Enable WDT
WDT Counter
128
INTRC Control
4
Programmable Postscaler
1:1 to 1:32,768
PIC18F87J90 FAMILY
25.2.1
The WDTCON register (Register 25-9) is a readable
and writable register. The SWDTEN bit enables or dis-
ables WDT operation. This allows software to override
the WDTEN Configuration bit and enable the WDT only
if it has been disabled by the Configuration bit.
Note 1: The CLRWDT and SLEEP instructions
2: When a CLRWDT instruction is executed,
WDT
CONTROL REGISTER
clear the WDT and postscaler counts
when executed.
the postscaler count will be cleared.
Reset
DS39933D-page 331
Wake-up from
Power-Managed
Modes
WDT
Reset