51 single chip microcomputer independent key linkage nixie tube LED buzzer

Catalog ：

        LED working principle 、 Circuit and source code

         Working principle of buzzer 、 Circuit and source code

         Working principle of nixie tube 、 Circuit and source code

         Working principle of independent keys 、 Circuit and source code

        summary

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LED principle , Circuit and source code         

        LED principle

                LED Light emitting diodes , There is single guide electricity , The greater the current, the greater the brightness , But if the current is too large, it will be burned ., In order to prevent excessive current, a resistor is usually connected in series .

        LED circuit

        stay 51 Single chip microcomputer A2 The circuit in the series is shown below , You can see LED It's a common anode , Lighten up LED Wait, just make P2 Port low level is enough .

         Source code

        Control individual LED The light is on

        

        control LED The light flashes

                

Working principle of buzzer 、 Circuit and source code

         Working principle of buzzer

                51 The single chip microcomputer adopts a piezoelectric buzzer , That is, output a pulse signal of a certain frequency （ High and low level ） Then you can make a sound .

         Buzzer circuit

                 51 Single chip microcomputer A2 The circuit of series buzzer is shown in the figure , take P2^5 Pin No. 1 outputs a certain high and low level of frequency .

        

         Source code

         

   Working principle of nixie tube 、 Circuit and source code

          Working principle of nixie tube

                  Inside it is a light-emitting diode .51 The eight digital tubes in the single chip microcomputer are all common cathode . That is to say, the common cathode of eight light-emitting diodes of a nixie tube , The common female port of the eight nixie tubes consists of 74HC138(38 Decoder ) control . The anodes of eight nixie tubes should be matched one by one 74HC245 Chip control .

        Nixie tube circuit

                 The following figure shows the nixie tube circuit in turn ,38 Decoder circuit , as well as 38 The truth table of the decoder . The truth table shows 38 How does the decoder control the common cathode effectively .（ Binary system 7<111> From left to right corresponds to 38 Of the decoder C,B,A, This helps us to control the common cathode ）

                

                

                        

         Source code

                 

 

  Working principle of independent keys 、 Circuit and source code

         Working principle of independent keys

                51 Single chip microcomputer A2 Series independent keys have pull-up resistors , High level detected without pressing the corresponding port , Press to switch on GND The corresponding port detects a low level . There is jitter when the key is pressed , Jitter will cause press, which is a misjudgment caused by jitter , So we need to shake . Deblocking includes software deblocking and hardware deblocking , The common hardware anti jitter is to connect capacitors , Capacitor charging can eliminate jitter by skipping the jitter time . We often use software to eliminate jitter .

        Independent key circuit

                

        Source code

                

 

  summary

        The following figure shows some pin definitions and main functions