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???
05/04/07 02:40
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#138582 - Round 3 - Hopefully better
Responding to: ???'s previous message
Ok, so lots of changes here based on the information you guys provided.

1) (S-R) latch schematic symbol updated (and more importantly I understand why).
2) As Eric pointed out, power-up is sort of a race condition. Although it's not a big deal in my app, I'm hoping my method would result in an off condition. I'm relying on the RESET input charging up slower than the SET latch. Whatcha think?
3) I've flipped the ON logic to the SET side of the latch. The old circuit I posted was actually from a previous project that used negative on logic.
4) I've removed the option for the microcontroller to force a turn-on. This isn't a feature i want or need. However, I should still be able to drive the latch off by applying a logic zero to FORCEOFF.
5) Similarlly to Michael's circuit, I now have a on\off button press detection and as such should be able to react accordingly (special modes or powering the device off).



Looking for any other ideas or suggestions. I certainly could have misunderstood something so any help is appreciated.

Bruce

List of 53 messages in thread
TopicAuthorDate
Momentary toggle soft switch with flip-flop?            01/01/70 00:00      
   I don't like it.            01/01/70 00:00      
      How Bouncy            01/01/70 00:00      
         what good does 'minimum' do you            01/01/70 00:00      
   Schmidt trigger            01/01/70 00:00      
      Tricky...            01/01/70 00:00      
         rail to rail bounce            01/01/70 00:00      
      McKinney            01/01/70 00:00      
   4013 FF toggle circuit            01/01/70 00:00      
      Values?            01/01/70 00:00      
         Values of R1,R2 &R3? Look at PCB!            01/01/70 00:00      
            clocking a FF from an RC?            01/01/70 00:00      
               Agreed            01/01/70 00:00      
                  Follow the datsheet, that is design            01/01/70 00:00      
                  Why dismissing the flip-flop?            01/01/70 00:00      
                     dismissing the flip-flop?            01/01/70 00:00      
                        The CD4013 of Bruce's schematic            01/01/70 00:00      
                           The CD4013 of Bruce's schematic is shown as a f/f            01/01/70 00:00      
                              I answered to Bruce...            01/01/70 00:00      
                  The circuit shown,,,,            01/01/70 00:00      
                     Power Consumption            01/01/70 00:00      
   Overlooking the obvious?            01/01/70 00:00      
      Simpler?            01/01/70 00:00      
      Keymat            01/01/70 00:00      
   Why not a hard switch?            01/01/70 00:00      
      Requirements            01/01/70 00:00      
      Industrial designers is why            01/01/70 00:00      
         Fair enough!            01/01/70 00:00      
   Let The Microconroller Decide            01/01/70 00:00      
      dedicated microcontroller :-)            01/01/70 00:00      
      Interresting no flip-flop            01/01/70 00:00      
   dat is de bounce            01/01/70 00:00      
   The 4013 needs steep edges            01/01/70 00:00      
      caps            01/01/70 00:00      
      A Vauge Suggestion            01/01/70 00:00      
   additional parts            01/01/70 00:00      
      what pin of which chip in what package?            01/01/70 00:00      
         chip on drawing in generic post            01/01/70 00:00      
            slowig down the bugger is not going to make it clo            01/01/70 00:00      
   What about this?            01/01/70 00:00      
      what is 'SOFTSW"?            01/01/70 00:00      
      Seems OK Except...            01/01/70 00:00      
         nice to find a fellow "drawer of fuctions"            01/01/70 00:00      
            I find it eaasier to just...            01/01/70 00:00      
               We appreciate it            01/01/70 00:00      
      Further Analysis....            01/01/70 00:00      
      Would this work?            01/01/70 00:00      
      All comments noted            01/01/70 00:00      
   Round 3 - Hopefully better            01/01/70 00:00      
      Round 4 is the winner            01/01/70 00:00      
         Tomas?? Bruce?? Are you a schizo?            01/01/70 00:00      
            haha, yes            01/01/70 00:00      
         A bit confusing...            01/01/70 00:00      

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