Post by thread:[PIC]:Watchdog timer reset in 16f84

Hello all I am not clear on how to reset the watchdog timer in a 16f84. I have a controller that I would like to have a reset function, in the event it would lock up or not function properly. I understand how to enable the watchdog but how do I reset to keep it from constantly resetting the micro. Thanks in advance Bill Shultz N8HKI -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

William Shultz wrote: > > Hello all > > I am not clear on how to reset the watchdog timer in a 16f84. > I have a controller that I would like to have a reset function, in the event it would lock up or not function properly. I understand how to enable the watchdog but how do I reset to keep it from constantly resetting the micro. > > Thanks in advance > > Bill Shultz N8HKI You have to put CLRWDT instructions in strategic places in your code. -- Best regards Tony mICros http://www.bubblesoftonline.com spam_OUTsalesTakeThisOuTbubblesoftonline.com -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> You have to put CLRWDT instructions in strategic > places in your code By "strategic", Tony means that the CLRWDT instruction must be executed within the time period of the WDT. If, for example, you have no pre-scaler on the WDT it will reset the PIC every 18ms. To avoid that, you must make sure by some means in your software that the CLRWDT is executed before each and every expected WDT reset. How you do that depends on the structure of your program. Although I haven't done this myself, you could use the TMR0 interrupt to call a routine with CLRWDT in it if you do not have convenient looping withing the program otherwise. As you also wish to have a reset in case of a fault, you should be able to arrange things so that the CLRWDT is not executed in that case. Using the pre-scaler with WDT will increase the reset period to a little over 2 seconds, which may or may not be useful to you. Note though that the pre-scaler has to be assigned to either WDT or TMR0 and that the division ratio of the pre-scaler is not the same with WDT as it is with TMR0 And you'll know that the F628 is preferable to the F84 if you're getting new stock -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> I understand how to enable the watchdog but how do I reset > to keep it from constantly resetting the micro. CLRWDT ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, .....olinKILLspam@spam@embedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Excecute the instruction CLRWDT in code that you know is OK. TTYL {Quote hidden}> -----Original Message----- > From: pic microcontroller discussion list > [PICLISTKILLspamMITVMA.MIT.EDU]On Behalf Of William Shultz > Sent: Wednesday, February 27, 2002 00:15 > To: .....PICLISTKILLspam.....MITVMA.MIT.EDU > Subject: [PIC]:Watchdog timer reset in 16f84 > > > Hello all > > I am not clear on how to reset the watchdog timer in a 16f84. > I have a controller that I would like to have a reset function, > in the event it would lock up or not function properly. I > understand how to enable the watchdog but how do I reset to keep > it from constantly resetting the micro. > > Thanks in advance > > Bill Shultz N8HKI > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics