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microprocessor reset monitor

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wookiebai

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hi folks

can anyone shed light on the function or basic attributes of a microprocessor reset monitor ??

the name suggests a lot but hey i cant assume anything
 
hi folks

can anyone shed light on the function or basic attributes of a microprocessor reset monitor ??

the name suggests a lot but hey i cant assume anything

hi,
I havn't used one those for some time, mainly on Z80 cpu's.

Dallas make a CPU reset ic.

Basically is a retriggerable monostable.
During the normal operation of cpu, the reset ic is triggered before it times out, which would cause a cpu reset.

The triggering can be part of the program or by 'tapping' into a cpu control signal line which is often called during the normal operation of the cpu.

The WDT watch dog timer in the PIC serves a similar function.

Does this explain it OK.?:)
EDIT:
DS1232
 

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  • DS1232.pdf
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emmm

maybe if you dumb it down a bit for me?

on the board i have, its a max 810 and its connected to the 87c52 (8051) microcontroller, oes the microcontroller double up as the cpu then in your explaination ?
 
emmm

maybe if you dumb it down a bit for me?

on the board i have, its a max 810 and its connected to the 87c52 (8051) microcontroller, oes the microcontroller double up as the cpu then in your explaination ?

hi,
Look at the pdf I have justed posted as an edit to my last post.:)

EDIT:

The MAX810 is a power supply supervisor monitor, which is quite different a watch dog timer, they detect a low voltage on the cpu supply line and reset the cpu.

A cpu that runs at too low voltage will go out of control and crash the system, a power up reset is required to regain control.
Like the Brown Out Detect on a PIC..
 

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  • MAX803-MAX810Z.pdf
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ah yes
that makes a bit more sense to me,
basically it prevents the system from losing power
and then losing the programable info

thanks for attachment
 
ah yes
that makes a bit more sense to me,
basically it prevents the system from losing power
and then losing the programable info

thanks for attachment

Problem with most PICs and cpu's if the power rail gets lowered to a certain point the signal/control lines in and out of the cpu and peripheral ic's dont switch correctly and the whole system goes belly up, until its manually reset.

If the power rail rises again without a 'firm' reset, the system could do bad things,, especially if its a life critical system.:eek:
 
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Aside from those functions mentioned above by Eric, One of the other important functions of the watch dog is to supervise the embedded software. At some point in the code, it has to strobe the wdog, or kick the dog as some software winki dinks call it.

The idea is, as long as the code is running without a hitch, the wdog is strobed, but if the code locks up, the strobe is not generated and the wdog times out and resets the board. Some systems have a way to store the last code executed in memory which can be read by debugger tools.
 
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