TMS370CX5X Datasheet, PDF (29/77 Pages) Texas Instruments – 8-BIT MICROCONTROLLER

TMS370Cx5x
8-BIT MICROCONTROLLER
SPNS010F – DECEMBER 1986 – REVISED FEBRUARY 1997
timer 1 module (continued)
The TMS370Cx5x device includes a 24-bit watchdog (WD) timer, contained in the T1 module, which can be
software-programmed as an event counter, pulse accumulator, or interval timer if the watchdog function is not
desired. The WD function is to monitor software and hardware operation and to implement a system reset when
the WD counter is not serviced properly (WD counter overflow or WD counter is reinitialized by an incorrect
value). The WD can be configured as one of the three mask options: standard watchdog, hard watchdog, or
simple counter.
D Standard watchdog configuration (see Figure 8) – for ’C75xA EPROM and mask-ROM devices
– Watchdog mode
– Ten different WD overflow rates ranging from 6.55 ms to 3.35 s at 5-MHz SYSCLK
– A WD reset key (WDRST) register is used to clear the watchdog counter (WDCNTR) when a correct
value is written.
– Generates a system reset if an incorrect value is written to the watchdog reset key or if the counter
overflows
– A watchdog overflow flag (WD OVRFL INT FLAG) bit that indicates whether the WD timer initiated a
system reset
– Non-watchdog mode
– Watchdog timer can be configured as an event counter, pulse accumulator, or an interval timer
WDCNTR.15-0
16-Bit
Watchdog Counter
Reset
WD OVRFL
INT FLAG
T1CTL2.5
T1CTL2.6
WD OVRFL
INT ENA
Interrupt
Clock
Prescaler
T1CTL1.7
WD OVRFL
TAP SEL
Watchdog Reset Key
T1CTL2.7
WD OVRFL
RST ENA
System Reset
WDRST.7-0
Figure 8. Standard Watchdog
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