IC for two bit address match

• IC for two bit address match
  Posted by Back2Volts on 16 Sep, 2017 16:24
• To detect match on a two bit address, other that using a 4x XOR gates chip, are there other simple options out there ?
• #1 Reply
  Posted by Benta on 16 Sep, 2017 16:47
• Search for "magnitude comparator". I know it's available in 4000 series CMOS, not sure about LS or HC/AC.
  
  
• #2 Reply
  Posted by edavid on 16 Sep, 2017 16:56
• Fixed address, jumper selectable, software selectable?
  
  Depending on the answer, you might use 74xx85, 74xx138/74xx139, 74xx151, 74xx266...
  
• #3 Reply
  Posted by Back2Volts on 17 Sep, 2017 02:30
• Quote from: edavid on 16 Sep, 2017 16:56

  Fixed address, jumper selectable, software selectable?
  
  Depending on the answer, you might use 74xx85, 74xx138/74xx139, 74xx151, 74xx266...
  

  
  Boring stuff.  Think of four identical modules plugged into a back plane bus.   Two connector pins hardwired in the back plane to set the slot address.   Two bus lines to address any one of the modules.   The modules have to react to match on the two pairs as being selected.
  
  From the suggestions it seems the best is still the 4x XNOR gates (or XOR for active LOW).   
  
  Thanks
• #4 Reply
  Posted by Benta on 17 Sep, 2017 10:07
• If it's just static decoding, I'd use 1/2 of a 74HC139. If you like, you can place four jumpers on the outputs, so each module can be configured to be address 0...3. Might be useful for swapping later on.
  
  
• #5 Reply
  Posted by Back2Volts on 18 Sep, 2017 16:31
• After thinking about it for a while, I am going to move the selection to a 74HC139 on the backplane and with select pins in the slot connectors.   It removes one chip from the slot boards.   
  
  I will still have a two pin hardwired slot address to build addresses of some I2C chips in the modules.    The modules will be identical, with no need for dip switches or jumpers.
  
  Thank you all.