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Forum: µC & Digital Electronics Digital push-button


Digital push-button
von Konstantinos (Guest)

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Dear μController community,

I am a complete beginner in the field so my question might seem a bit 
naive.
In short I need to implement a circuit switch that will change state 
(ON/OFF) every time a short pulse is sent (trigger). In effect it is a 
digital push-button. For instance on a first trigger the circuit open, 
on the 2nd will close..etc..

Do you have any simple solution to this? Is it something easy to 
implement with a μcontroller? I am currently looking for the simplest, 
least time consuming solution so if there is another way other than 
programming ICs please let me know.

Sincerely,
Konstantinos

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Re: Digital push-button
von MaWin (Guest)

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If the circuit does always have power,
than a simple flip flop does

1
  +-----------+  CD4011

2
  |           |                 

3
  |       +---)----------------+

4
  |       |   |                |

5
  |       +--|>o--10k--+--|>o--+-- on/off

6
  | +         |        |       |  

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Battery       |        |       1M

8
  | -         |        |   _   | 

9
  |           |        +--o o--+ 

10
  |           |                | 

11
  |           |              100nF

12
  |           |                |

13
  +-----------+----------------+


If you loose power, there are specialized
single bit non volatile state saver memory chips like
FM1105B, FM1106, FM1107, FM1110, FM1114 (RamTrom FERAM)

Of course you can program it also into a small micro controller
that has an EEPROM to save state during power loss.
For the Arduino programming environment

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char key=0, lastkey=0, savedkey;

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const char inputpin = 1;

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const char outputpin = 2;

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void setup()

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{

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    pinMode(inputpin,INPUT); 

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}

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void loop()

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{

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  while(1)

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  {

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    key=digitalRead(inputpin);

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    if(key==1&&lastkey==0)

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    {

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      savedkey=EEPROM.read(11);

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      savedkey=1savedkey;

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      EEPROM.write(11, savedkey);

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      digitalWrite(outputpin,savedkey)

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    }

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    lastkey=key;

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    delay(10);

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  }

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}

So this is rather simple.

  


  



  

  
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