PIC32MX440F256H-80I Datasheet, PDF (557/646 Pages) Microchip Technology – 64/100-Pin General Purpose and USB 32-Bit Flash Microcontrollers

PIC32MX3XX/4XX
26.0 WATCHDOG TIMER
Note:
This data sheet summarizes the features of
the PIC32MX3XX/4XX of devices. It is not
intended to be a comprehensive reference
source. Refer to the “PIC32MX Family
Reference Manual” (DS61132) for a
detailed description of this peripheral.
This section describes the operation of the Watchdog
Timer (WDT) and Power-Up Timer of the
PIC32MX3XX/4XX.
The WDT, when enabled, operates from the internal
Low-Power Oscillator (LPRC) clock source and can be
used to detect system software malfunctions by reset-
ting the device if the WDT is not cleared periodically in
software. Various WDT time-out periods can be
selected using the WDT postscaler. The WDT can also
be used to wake the device from Sleep or Idle mode.
Refer to Figure 26-1.
The following are some of the key features of the WDT
module:
• Configuration or software controlled
• User-configurable time-out period
• Can wake the device from Sleep or Idle
TABLE 26-1: RESULTS OF A WDT TIME-OUT EVENT FOR AVAILABLE MODES OF
DEVICE OPERATION
Device Mode
Device Reset
Generated
Non-
Maskable
Interrupt
Generated
WDTO⁽¹⁾ Bit
Set
SLEEP⁽¹⁾ Bit
Set
IDLE⁽¹⁾ Bit Set
Awake
Yes
No
Yes
No
No
Sleep
No
Yes
Yes
Yes
No
Idle
No
Yes
Yes
No
Yes
Note 1: Status bits are in the RCON register.
Device
Registers
Reset
Yes
No
No
FIGURE 26-1:
WATCHDOG AND POWER-UP TIMER BLOCK DIAGRAM
PWRT Enable
WDT Enable
LPRC
Oscillator
WDTCLR = 1
WDT Enable
Wake
1:64 Output
PWRT Enable
LPRC
Control
PWRT
Clock
1
25-bit Counter
25
WDT Counter Reset
0
Device Reset
1
NMI (Wake-up)
Power Save
Decoder
FWDTPS<4:0>(DEVCFG1<20:16>)
© 2008 Microchip Technology Inc.
Preliminary
DS61143E-page 555