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???
10/10/11 14:15
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 		 #184158 - Why ever source current for driving LEDs?
Responding to: ???'s previous message
Erik Malund said:
I'd say the first clue was when P0 was used to drive the LED's.
if the LEDs are Vcc to pin this is valid.

Erik

Isn't it almost uniformly so? No processor I have seen can sink less current than it can source. But lots of processors have problems sourcing current. More than one processor have also extra ground pins, that can take care of the current from VCC and all processor pins that are sinking significant amounts of current.

Another thing is that lots of processors defaults to have a weak pull-up in reset state. This weak pull-up is often enough to get at least red LEDs to glow visibly.

Yes, some processor are more than capable of sourcing current to drive LEDs. But is there a reason to?


List of 36 messages in thread
TopicAuthorDate
Speed control of running adancing LEDs            01/01/70 00:00      
   Duplicate Posting            01/01/70 00:00      
      This is just an inadequately understood homework problem            01/01/70 00:00      
   Design your code, make it pretty.            01/01/70 00:00      
   RE: please suggest some idea            01/01/70 00:00      
      I totally agree with ANDY            01/01/70 00:00      
         Very unhelpful comments            01/01/70 00:00      
            Thank you sir            01/01/70 00:00      
               While analysing the problem            01/01/70 00:00      
               Translation into assembler task of programmer.            01/01/70 00:00      
   'subb' instruction            01/01/70 00:00      
      Yes, debounce is definitely good to have.            01/01/70 00:00      
         Got Success !            01/01/70 00:00      
            What is the final code?            01/01/70 00:00      
               homework is done..            01/01/70 00:00      
               Surely not secret, at least for my seniors            01/01/70 00:00      
               Teacher will know            01/01/70 00:00      
                  Don't worry            01/01/70 00:00      
                     What code?            01/01/70 00:00      
                     You must show your effort.            01/01/70 00:00      
                        yes, it's another "gimmee", yet nobody sees it            01/01/70 00:00      
                           what's the problem            01/01/70 00:00      
                              Why ever source current for driving LEDs?            01/01/70 00:00      
                              true enough, but is that what he did?            01/01/70 00:00      
                           I think everybody saw that?            01/01/70 00:00      
                              Cleverness            01/01/70 00:00      
                                 Stange !            01/01/70 00:00      
                                    because it is            01/01/70 00:00      
                                    Yes, often very obvious when copied code turned in            01/01/70 00:00      
                              I agree with Andy            01/01/70 00:00      
                                 the key word is 'help'            01/01/70 00:00      
                                    May not be an achievement for you            01/01/70 00:00      
                                       So ... where's the evidence of your struggle?            01/01/70 00:00      
                                    problem can be outside            01/01/70 00:00      
                                    This is certainly correct!            01/01/70 00:00      
   About sinciarity            01/01/70 00:00      

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