BS2 and RFID Reader.... How to know when the reader is inactive

Jeff_5_

ok so i have a parallax rfid reader hooked into my basic stamp. I read my tags in the the VAR buf. My question is how can i determine when the reader is not reading a tag. My thought was to set the buf=0 and then do this piece of code.

LOWEnable 'activatethereader
SERINRX,T2400,150,Notag_,[WAIT($0A),SKIP6,HEX4buf] 'waitforhdr+ID
HIGHEnable

And if my reader dosnt read a tag my buf should still equal zero. So then i can say

If(buf = 0) THEN
Debug "There is no tag in range"

Anybody know how i can do this.

Franklin

Have you tried that? If so what did you get?

W9GFO

Jeff_5_ wrote: »

My question is how can i determine when the reader is not reading a tag. My thought was to set the buf=0 and then do this piece of code.

LOW Enable    'activate the reader
SERIN RX, T2400, 150, Notag_, [WAIT($0A), SKIP6, HEX4 buf]     'waitforhdr+ID
HIGH Enable

And if my reader dosnt read a tag my buf should still equal zero. 
So then i can say

 If (buf = 0) THEN 
Debug "There is no tag in range"

Anybody know how i can do this.

The "Notag_" part is the name of a subroutine that the program jumps to if the tag reading times out. The "150" before it is the time in milliseconds that it waits to read a tag before making the jump. If a tag is read then the jump is not made.

Rich H

Jeff_5_

ok that makes sense but how do sub routies work.

can i just go

NotTag:

debug "There is no tag in range"

W9GFO

Yes, that's pretty much it.

See if this works;

' {$STAMP BS2}
' {$PBASIC 2.5}


RX       PIN   5  ' change to suit
Enable   PIN   3  ' change to suit

tag     VAR      Word(5)     ' an array of 5
buf     VAR      Word
i       VAR      Byte

T2400   CON      396

Main:

DO

FOR i = 0  TO 4
 LOW Enable    'activate the reader
 SERIN RX, T2400, 150, Notag, [WAIT($0A), SKIP 6, HEX4 buf]
 HIGH Enable

  SELECT buf      ' look at contents of buf

    CASE tag(0)   ' if buf = the first tag
      DEBUG "This is tag 1"
      EXIT        ' exit the FOR..NEXT loop
    CASE tag(1)
      DEBUG "This is tag 2"
      EXIT
    CASE tag(2)
      DEBUG "This is tag 3"
      EXIT
    CASE tag(3)
      DEBUG "This is tag 4"
      EXIT
    CASE tag(4)
      DEBUG "This is tag 5"
      EXIT
    CASE ELSE
      DEBUG "This tag stored as tag ", DEC i+1
      tag(i) = buf
  ENDSELECT

NEXT
GOTO Main

Notag:

DEBUG "There is no tag in range"

LOOP

Rich H