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Kai Klaas
04/03/10 15:05
Modified:
  04/03/10 15:10

Read: 504 times
Germany


 
#174821 - It's a highly dynamical thing...
Responding to: ???'s previous message
Rickey said:
And in something simple like statically showing a number on a 7 seg I don't see why it needs to be reset.

A microcontroller is a thing that is highly dynamically running inside. There's a clock which must start up at power-on and which only works properly after a few milliseconds. Then, there's an auxiliary potential to be generated about twice the supply voltage to allow the flash to be burned. Also, many registers and flip-lops, all the counters, PCAs, watchdog, UARTs are in a random state which must be initialized. In fact, there's nothing more important than a proper reset, one which highly reliably works at power-on, power-off and during supply voltage dips (brown-out conditions).

In conjunction with the AT89S51/52, which you probably intend to use, I usually take a MAX1232, which contains not only a reset circuitry but also a watchdog, like in this example circuit:

http://www.8052.com/forum/read/109257

and here

http://www.8052.com/forum/read/109412

Kai Klaas

List of 24 messages in thread
TopicAuthorDate
New with MCUs need a little help.      Rickey Ward      04/02/10 14:43      
   Hi      Jez Smith      04/02/10 15:30      
      Some answers but now concerns      Rickey Ward      04/02/10 21:36      
         Normally very weak source      Per Westermark      04/02/10 21:41      
            Can't find that detail      Rickey Ward      04/02/10 21:55      
               Not many 805x's have push-pull outputs.      Richard Erlacher      04/02/10 22:21      
         Reset      Jez Smith      04/03/10 00:39      
         SDCC      Jez Smith      04/03/10 00:42      
   Books      Andy Neil      04/03/10 05:02      
   Electronics      Andy Neil      04/03/10 05:05      
   first read "the bible"      Erik Malund      04/03/10 05:56      
      Maybe not First?      Andy Neil      04/03/10 06:09      
         Rickey?      Erik Malund      04/03/10 06:21      
            I am new, Just somthing I wanted to do.      Rickey Ward      04/03/10 10:46      
      Dead links      Rickey Ward      04/03/10 10:50      
         No you are right      Jez Smith      04/03/10 12:47      
            hrm      Rickey Ward      04/03/10 14:32      
               Argh!!!      Jez Smith      04/03/10 14:39      
               It's a highly dynamical thing...      Kai Klaas      04/03/10 15:05      
                  a reset writeup, but you don't want to read it now      Jan Waclawek      04/03/10 15:53      
                     You mean this one?      Kai Klaas      04/03/10 19:52      
                        Thanks      Rickey Ward      04/03/10 22:16      
         not dead, just incorrectly copied      Jan Waclawek      04/03/10 13:56      
            Thanks      Rickey Ward      04/03/10 14:32      

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