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08/05/06 09:02
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 		 #121687 - Does logic "low" represent 0V?
I am trying to connect a buzzer to P1.0 of my AT80C51ED2 MCU. I am trying to switch on/off the buzzer but with no success. Here is my connection :


+5V ----- +|------|
|Buzzer|
+-- -|------|
|
|
P1.0 of MCU

Here is my understanding and i might be wrong. When i set P1.0 = 0, does that means that would turn on the buzzer since there is a potential difference between the the Vcc(+5V) and the P1.0(0V)? And if i bring the P1.0 high a.k.a "1", it would cause the Buzzer to turn off. Of course i did place a resistor between the buzzer to P1.0 of the MCU as a current limiter.

Also, to my surprise when i try to use a voltmeter to measure between the P1.0 and GND pin of the MCU, i still get approximately +5V even though i pulled the P1.0 to low by setting P1.0 = 0. Can someone please explain why does this happens and tell me where is my mistake. Thank you in advance!


List of 40 messages in thread
TopicAuthorDate
Does logic "low" represent 0V?            01/01/70 00:00      
   The diagram does not work            01/01/70 00:00      
      What current are we talking about?            01/01/70 00:00      
      More details needed!            01/01/70 00:00      
   Using a transistor            01/01/70 00:00      
      Yes, but...            01/01/70 00:00      
         bear in mind            01/01/70 00:00      
            Of course, but...            01/01/70 00:00      
         forgot to mention: cookbook was for a piezo buzzer            01/01/70 00:00      
            In such a case...            01/01/70 00:00      
      Low hissing sound            01/01/70 00:00      
         Try            01/01/70 00:00      
            Circuit details and summary of my problem            01/01/70 00:00      
               either a mistype or connecting the buzzer the wron            01/01/70 00:00      
                  Update            01/01/70 00:00      
                     Please do as I have asked: connect the buzzer            01/01/70 00:00      
               What you tell is confusing...            01/01/70 00:00      
                  As mentioned by Kai Klaas            01/01/70 00:00      
                     Do not 'believe' MEASURE and be sure            01/01/70 00:00      
               Solving buzzer problem            01/01/70 00:00      
   Barbecue?            01/01/70 00:00      
   Type of buzzer            01/01/70 00:00      
      who knows how much power, how big spikes            01/01/70 00:00      
      Again...            01/01/70 00:00      
         Yeah            01/01/70 00:00      
            Try this!            01/01/70 00:00      
               just guessing            01/01/70 00:00      
                  guessing the current is below 5A...            01/01/70 00:00      
                     then what if it is 1uA            01/01/70 00:00      
                        Sorry.            01/01/70 00:00      
                     We just do not want to guess!!            01/01/70 00:00      
                        Sorry.            01/01/70 00:00      
                           No need to appologize, dear Leonardo...            01/01/70 00:00      
                           not a metter of apology            01/01/70 00:00      
               Buzzer Problem Solved            01/01/70 00:00      
                  Nice to know            01/01/70 00:00      
   No longer interested, Eugene??            01/01/70 00:00      
      of course not            01/01/70 00:00      

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