Prescaler
(1:128 ratio)
Counter
(32−bit)
WDTi_FCLK
RESET
IRQ
Registers
L4 interface
Watchdog timer
Interrupt
generation
WATCHDOG
20.4.3 Functional Description
20.4.3.1 Power Management
There are two clock domains in the watchdog timers:
•
Functional clock domain: WDTi_FCLK is a 32 kHz watchdog timer functional clock. It is used to clock
the watchdog timer internal logic.
•
Interface clock domain: WDTi_ICLK is a 125 MHz watchdog timer interface clock. It is used to
synchronize the watchdog timer L4 port to the L4 interconnect. All accesses from the interconnect are
synchronous to WDTi_ICLK.
In this device, the clocks to the watchdog timers are always On. The clocks cannot be turned off, if the
watchdog timers is not being used.
20.4.3.2 Interrupts
list the event flags, and their masks, that cause module interrupts.
Table 20-101. Watchdog Timer Events
Event Flag
Event Mask
Mapping
Comments
WDT_WIRQSTAT[0] EVENT_OVF
WDT_WIRQENSET/WDT_WIRQENCLR[0]
WDTINT
Watchdog timer overflow
OVF_IT_ENA
WDT_WIRQSTAT[1] EVENT_DLY
WDT_WIRQENSET/WDT_WIRQENCLR[1]
WDTINT
Watchdog delay value
DLY_IT_ENA
reached
20.4.3.3 General Watchdog Timer Operation
The watchdog timers are based on an upward 32-bit counter coupled with a prescaler. The counter
overflow is signaled through two independent signals: a simple reset signal and an interrupt signal, both
active low.
is a functional block diagram of the watchdog timer.
The interrupt generation mechanism is controlled through the WDT_WIRQENSET/WDT_WIRQENCLR
and WDT_WIRQSTAT registers.
The prescaler ratio can be set from 1 to 128 by accessing the WDT_WCLR[4:2] PTV bit field and the
WDT_WCLR[5] PRE bit of the watchdog control register (WDT_WCLR).
The current timer value can be accessed on-the-fly by reading the watchdog timer counter register
(WDT_WCRR), modified by accessing the watchdog timer load register (WDT_WLDR) (no on-the-fly
update), or reloaded by following a specific reload sequence on the watchdog timer trigger register
(WDT_WTGR). A start/stop sequence applied to the watchdog timer start/stop register (WDT_WSPR) can
start and stop the watchdog timers.
Figure 20-97. 32-Bit Watchdog Timer Functional Block Diagram
3673
SPRUH73H – October 2011 – Revised April 2013
Timers
Copyright © 2011–2013, Texas Instruments Incorporated