timers-016
Prescaler
(1:128 ratio)
Counter
(32-bit)
WDTi_FCLK
RESET
IRQ
Registers
L4 interface
Watchdog timer
Interrupt
generation
Public Version
Watchdog Timers
www.ti.com
Table 16-61. WDT Interrupt Names and Processor IRQ Mapping
Timer
Interrupt Name
Mapping
Comments
MPU WDT
WDT2_IRQ
Not connected
IVA2 WDT
WDT3_IRQ
M_IRQ_36
IVA2 WDT overflow
16.4.3 WDTs Functional Description
16.4.3.1 General WDT Operation
The WDTs 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.
The use of these signals depends on whether they are connected or not. For this information, see
. The interrupt generation mechanism is controlled through the WDTi.
and WDTi.
registers.
The prescaler ratio can be set between 1 and 128 by accessing the WDTi.
[4:2] PTV and
WDTi.
[5] PRE fields of the watchdog control register (WDTi.
The current timer value can be accessed on-the-fly by reading the WDT counter register (WDTi.
modified by accessing the WDT load register (WDTi.
) (no on-the-fly update), or reloaded by
following a specific reload sequence on the WDT trigger register (WDTi.
). A start/stop sequence
applied to the WDT start/stop register (WDTi.
) can start and stop the WDT.
Figure 16-16. 32-Bit WDT Functional Block Diagram
16.4.3.2 Reset Context
After reset, the WDTs are enabled.
lists the default reset values of the three WDT load
registers (WDTi.
) and prescaler ratios (WDTi.
[4:2] PTV field). To get these values, software
must read the corresponding WDTi.
[4:2] PTV fields and the 32-bit register to retrieve the static
configuration of the module.
Table 16-62. Count and Prescaler Default Reset Values
Timer
Reset Value
PTV Reset Value
DEVICE WDT (WDT2)
0xFFFB 0000
0
IVA2 WDT (WDT3)
0xFFFB 0000
0
16.4.3.3 Overflow/Reset Generation
When the WDT counter register (WDTi.
) overflows, an active-low reset pulse is generated to the
PRCM module. This pulse is one prescaled timer clock cycle wide and occurs at the same time as the
timer counter overflow.
2750
Timers
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated