input for fsk circuit

Discussion in 'The Projects Forum' started by darryl, Nov 21, 2010.

  1. darryl

    Thread Starter Member

    May 1, 2009
    14
    0
    Hello. You guys are my last hope. I want to remotely control n number of switches, which we know can be reduced to an n bit word. Lets say 8.
    Do I start off with a 8 bit priority encoder? Trouble is, that is an 8 bit output and I cannot find an fsk circuit with 8 inputs. Can someone please tell me how to get from 8 bits into the fsk circuit. Do I need some kind of serial feed?
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You could use something like a 4021 parallel-in, serial-out 8-bit static shift register.
    The 4021 is prefixed with CD, HCF, HEF, MC1 or TC, depending on the manufacturer.

    There are a number of "flavors" of shift registers; serial in, serial out; serial in, parallel out; parallel in, serial out, and universal shift registers. Some have latching inputs, like the 4021.

    There are also 74HC versions that you could use, like perhaps a 74HC165, 166, or a 299 universal shift register.
     
  3. windoze killa

    AAC Fanatic!

    Feb 23, 2006
    605
    24
    How many switches do you want to control? If you have a decimail to binary encoder/decoder system you could get 16 switches operating with only 4 bits. Multiplexer circuits could do similar things. Can you supply a bit more info? How many switches? what FSK chip you are using?
     
  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Are you working on the sending side or receiving side? What is the distance/medium of transmission?

    Does either side currently exist? If so, do you have a schematic?
     
  5. darryl

    Thread Starter Member

    May 1, 2009
    14
    0
    Thanks for the tip about the shift register. If I get stuck, I`ll give you a call...lol
    I actually want 32 switches. I`m still right at the beginning of the circuit. So far,
    it looks like I need a priority encoder first. Can someone help with a circuit or suggestions
    for that? Should I go discrete or string a bunch of priority encoders together or maybe
    multiplex?
     
    Last edited: Nov 24, 2010
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