' CheckQtiSubroutine.bs2
' Displays QTI sensor states. 0 means white surface, 1 means black.

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


qtis VAR Nib                  ' qti black/white states

OUTB = %1111                  ' Set OUTB bits to 1

DEBUG CRSRX, 8, "FMMF", CR,   ' Display bit positions
      CRSRX, 8, "LLRR", CR

DO                            ' Main DO...LOOP
  GOSUB Check_Qtis            ' Get QTI states
  DEBUG BIN4 ? qtis, CRSRUP   ' Display QTI states
  PAUSE 100                   ' 1/10 s delay
LOOP

Check_Qtis:
' Result -> qtis variable. 0 means white surface, 1 means black
' surface.

  DIRB = %1111                  ' P7..P4 -> output
  PAUSE 0                       ' Delay = 230 us
  DIRB = %0000                  ' P7..P4 -> input
  PAUSE 0 ' Delay = 230 us
  ' PULSOUT UnusedPin, 0        ' Delays = 208 + (Duration*2) us
  qtis = INB ' Store QTI outputs in INB

  RETURN