pc87591l-n05 National Semiconductor Corporation, pc87591l-n05 Datasheet - Page 160

• Manufacturer Part Number: pc87591l-n05
• Description: Lpc Mobile Embedded Controller
• Manufacturer: National Semiconductor Corporation

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4.0 Embedded Controller Modules
4.10 TIMER AND WATCHDOG (TWD)
The Timer and Watchdog module (TWD) generates the clocks and interrupts used for timing periodic functions in the system.
It also provides watchdog protection over software execution.
The TWD provides flexibility in system configuration by enabling the configuration of various clock ratios. After setting the
TWD configuration, the software can lock the it to provide a higher level of protection against subsequent erroneous software
action. Once a section of the TWD is locked, only reset releases it. Figure 58 shows the TWD block diagram.
4.10.1 Features
• 32.768 KHz input clock
• Programmable pre-scale counter
• 16-bit programmable periodic interrupt timer
• 8-bit watchdog timer
• Watchdog signal generation in response to failure detection, such as:
• Watchdog input clock selector
• Watchdog Freeze input
• Configuration lock option for fully protected watchdog
• Data match mechanism for watchdog touch
— Watchdog service performed too early
— Watchdog service performed too late
— Wrong DATA used in a service by data match
LFCLK
(32.768 KHz)
(DEV Env. only)
FREEZE
WDCT0I bit (TWCFG Register)
Figure 58. Timer and Watchdog Block Diagram
5-Bit Pre-Scale
(Continued)
Counter
(TWCP)
TWDT0 Register
16-Bit Timer
WDSDM
WDCNT
160
Watchdog
T0IN
Peripheral Bus
Watchdog
Service
Logic
Watchdog
Signal
T0OUT
to Reset Circuit
to ICU
T0IN
to ACM
Revision 1.2