MFC2000 datasheet(138/426 Pages) ETC

номер детали	MFC2000

подробное описание детали	Multifunctional Peripheral Controller 2000

PDF	426 Pages

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производитель	ETC [List of Unclassifed Manufacturers]

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MFC2000 Multifunctional Peripheral Controller 2000

Hardware Description

5-12

Conexant

100723A

As soon as the Watchdog Timer is enabled, the Time-out Down Counter begins counting.

The Time-out Down Counter is decremented based on a 1 ms pulse which is derived from (125 µs prescaler

period /8); the count occurs on the rising edge of SIUCLK.

After the Time-out Down Counter reaches 'zero', the (internal) watchdog reset signal becomes active at the next 1

ms pulse. The watchdog reset immediately activates the internal resn and external RESETn signals. These resets

are deactivated when the Power Up Delay 2 timer times out (i.e., 8 SIUCLK's).

In order to prevent the Watchdog Timer from timing-out and generating a reset pulse, it must be retriggered by

writing $0F followed by $F0 to the WatchdogEnRetrigger register. This action causes the value in the

WatchdogInterval register to be re-loaded into the Time-out Down Counter.

Note:

The 125us prescaler must be initialized before activating the watchdog timer.

BLOCK 1, 2, 3, 4, and 5

RESETn

1ms pulse

SIUCLK

DATA

BUS

WATCHDOG

TIMER

CONTROL

WATCHDOG

ENRETRIGGER

WATCHDOG

RESET

GENERATOR

TIME-OUT DOWN

COUNTER

DATA

BUS

WATCHDOG

INTERVAL

WDRE

Figure 5-8. Watchdog Timer Block Diagram

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