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Read-Only
Author
Joseph George
Posted
20-Dec-2001 08:32 GMT
Toolset
C51
New! Can a WDT of .........
Hello,

Can a watchdog timer of AT89s8252 reset the CPU in case of program
crash ??? .I couldnt find this info PLEASE HELP !! .


Kind Regards

JG
Read-Only
Author
Andrew Neil
Posted
20-Dec-2001 08:56 GMT
Toolset
C51
New! RE: Can a WDT of .........
That is the whole point of a Watchdog Timer!
Read-Only
Author
joseph george
Posted
20-Dec-2001 10:27 GMT
Toolset
C51
New! RE: Can a WDT of .........
hi All,

Thanks for reply Andrew ,But I need a little more clarification I am confused about the WDT working somewhere it is resetting the CPU after sensing the voltage drop and at some places it resets the cpu after sensing the program crash .Please tell me What method of WDT is being adopted in AT89s8252.

Kind Regards
JG
Read-Only
Author
Andrew Neil
Posted
20-Dec-2001 10:52 GMT
Toolset
C51
New! RE: Can a WDT of .........
I think you are confusing a "supervisor", which monitors things like supply voltage, with a Watchdot Timer (WDT).

A WDT is simply a timer which will reset the CPU if you allow it to time-out.

Of course, some devices implement both a "supervisor" and a WDT (and also a Reset generator) into a single device - but the functions are distinct.

I'm afraid I don't know the detail of the AT89s8252 - but I'm sure you can read the datasheet as well as I could!
Read-Only
Author
Christian Bienert
Posted
20-Dec-2001 12:21 GMT
Toolset
C51
New! RE: Can a WDT of .........
I think you have the dokumentation from atmel, if not here are the links.

http://www.atmel.com/atmel/acrobat/doc0499.pdf
http://www.atmel.com/atmel/acrobat/doc0401.pdf

If you use only the internal WDT you have to retrigger the WDT, otherwise you get the reset (by software).

If you had an external WDT (from Maxim o.e) remeber that you cant go into power down mode because your program will stop and cant retrigger the external watchdog with results in an hardware reset by the external WDT.

if you use emulators you should know that when you stop your programm it is possible that the internal WDT is not stopped so you get a reset.

In fact, there are many sources for your problem and we dont know your hardware ans software implementation.

merry xmas, chris *<|:-)
Read-Only
Author
Joseph George
Posted
20-Dec-2001 14:19 GMT
Toolset
C51
New! RE: Can a WDT of .........
Thanks a Lot Guys .I think Andrew is right I am confusing WDT with a supervisory IC .

Kind Regards

JG

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