Datasheet

 2010-2013 Microchip Technology Inc. DS39881E-page 217
PIC24FJ64GA004 FAMILY
24.3.1 WINDOWED OPERATION
The Watchdog Timer has an optional Fixed Window
mode of operation. In this Windowed mode, CLRWDT
instructions can only reset the WDT during the last 1/4
of the programmed WDT period. A CLRWDT instruction
executed before that window causes a WDT Reset,
similar to a WDT time-out.
Windowed WDT mode is enabled by programming the
WINDIS Configuration bit (CW1<6>) to ‘0’.
24.3.2 CONTROL REGISTER
The WDT is enabled or disabled by the FWDTEN
Configuration bit. When the FWDTEN Configuration bit
is set, the WDT is always enabled.
The WDT can be optionally controlled in software when
the FWDTEN Configuration bit has been programmed
to ‘0’. The WDT is enabled in software by setting the
SWDTEN control bit (RCON<5>). The SWDTEN
control bit is cleared on any device Reset. The software
WDT option allows the user to enable the WDT for
critical code segments and disable the WDT during
non-critical segments for maximum power savings.
FIGURE 24-2: WDT BLOCK DIAGRAM
LPRC Input
WDT Overflow
Wake from Sleep
31 kHz
Prescaler
FWPSA
SWDTEN
FWDTEN
Reset
All Device Resets
Sleep or Idle Mode
LPRC Control
CLRWDT Instr.
PWRSAV Instr.
(5-bit/7-bit)
WDTPS<3:0>
1 ms/4 ms
Exit Sleep or
Idle Mode
WDT
Counter
Transition to
New Clock Source
1:1 to 1:32.768
Postscaler