In RFID, are there tag modules that give the user a choice of different outputs

debouncemicrocontrollerrfid

I look for an RFID tag that gives you the option to 'choose the output'. For example, you want to choose an RFID-output from a list of X possible outputs using a multi-directional switch with X directions.

Does something like that exist? What resolutions of X are there available? How small can it be?

If not, how could you go about designing the thing? Just slide the antenna over the desired Chip from a number of X chips and do some debouncing? Or use just one chip but connect one out of its X inputs with a further circuit and a debounce?! (and what type of circuit?)

Furthermore, how does one tackle higher resolutions for X without making it bulky (as there is just not enough room to make it work with debouncing and different chips and the mechanics and all)?

Best Answer

RFID tags are simple. A dedicated microprocessor with an eeprom, and a coil. Passive tags derive their power from the RFID field of the reader, and then respond with their eeprom contents, either a serial number or string. Simple. You can make one with any microcontroller if you follow the standard. If you want a tag that can be selective of the string it outputs, then you use standard microcontroller circuits and programming to get that done. The RFID part can be just the microcontroller, a coil (or inductor), and maybe a capacitor.

A DIP switch and a few input pins:

schematic

Pseudo code:

   SetupRFID()
   While(1){
    ReadInputs()
      If Input1 + Input2 + Input3 + Input4 == 4
      then TagOutput == String4
      else if Input1 + Input2 + Input3 + Input4 == 3
      then TagOutput == String3
      else default TagOutput == String0
      delay for 1 second
    }

Aside from the link that @0x6d64 provided (http://dimme.net/rfid-tag-emulation-with-an-avr/), there is also http://scanlime.org/2008/09/using-an-avr-as-an-rfid-tag/ and http://hackaday.com/2011/09/26/barebones-pic-rfid-tag/

Related Topic