TMP93CS44 datasheet(186/224 Pages) TOSHIBA

186 / 224 page

TMP93CS44/S45

2004-02-10

93CS44-184

The watchdog timer consists of 7-stage and 15-stage binary counters which use system

clock (fSYS) as the input clock. The 15-stage binary counter has fSYS/215, fSYS/217, fSYS/219

and fSYS/221 output. Selecting one of the outputs with the WDMOD<WDTP1:0> register

generates a watchdog timer interrupt and outputs watchdog timer out when an overflow

occurs. The binary counter for the watchdog timer should be cleared to 0 with runaway

detecting result software (Instruction) before an interrupt occurs.

Example:

LDW

(WDMOD), B100H

; Disable.

(WDCR), 4EH

; Write clear code.

SET

7, (WDMOD)

; Enable again.

The runaway detecting result can also be connected to the reset pin internally. In this

case, the watchdog timer resets itself.

Figure 3.12.2 Normal Mode

Figure 3.12.3 Reset Mode

For warm-up counter, 27 and 29 output of 15-stage binary counter can be selected using

WDMOD<WARM> register. When a stable-external oscillator is used, shorter warm-up

time is available using T45CR<QCU> register. When <QCU>

= 1, counting value 27 is

selected. When the watchdog timer is in operation, this shorter warm-up time function

cannot be available. This function can be available by setting <QCU>

= 0.

Overflow

WDT counter

WDT interrupt

WDT clear

(Software)

Clear code of write

WDT counter

WDT interrupt

8 to 20 states (12.8 to 32

µs at 20 MHz)

Overflow

Internal reset

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