Parallax Boe-Bot - Page 198

Page 184 · Robotics with the Boe-Bot
DO
' --- Detect Consecutive Alternate Corners ------------------------
' See the "How EscapingCorners.bs2 Works" section that follows this program.
IF (IN7 <> IN5) THEN ' One or other is pressed.
IF (old7 <> IN7) AND (old5 <> IN5) THEN ' Different from previous.
counter = counter + 1 ' Alternate whisker count + 1.
old7 = IN7 ' Record this whisker press
old5 = IN5 ' for next comparison.
IF (counter > 4) THEN ' If alternate whisker count = 4,
counter = 1 ' reset whisker counter
GOSUB Back_Up ' and execute a U-turn.
GOSUB Turn_Left
GOSUB Turn_Left
ENDIF ' ENDIF counter > 4.
ELSE ' ELSE (old7=IN7) or (old5=IN5),
counter = 1 ' not alternate, reset counter.
ENDIF ' ENDIF (old7<>IN7) and
' (old5<>IN5).
ENDIF ' ENDIF (IN7<>IN5).
' --- Same navigation routine from RoamingWithWhiskers.bs2 ------------------
IF (IN5 = 0) AND (IN7 = 0) THEN ' Both whiskers detect obstacle
GOSUB Back_Up ' Back up & U-turn (left twice)
GOSUB Turn_Left
GOSUB Turn_Left
ELSEIF (IN5 = 0) THEN ' Left whisker contacts
GOSUB Back_Up ' Back up & turn right
GOSUB Turn_Right
ELSEIF (IN7 = 0) THEN ' Right whisker contacts
GOSUB Back_Up ' Back up & turn left
GOSUB Turn_Left
ELSE ' Both whiskers 1, no contacts
GOSUB Forward_Pulse ' Apply a forward pulse
ENDIF ' and check again
LOOP
' -----[ Subroutines ]--------------------------------------------------------
Forward_Pulse: ' Send a single forward pulse.
PULSOUT 13,850
PULSOUT 12,650
PAUSE 20
RETURN
Turn_Left: ' Left turn, about 90-degrees.
FOR pulseCount = 0 TO 20
PULSOUT 13, 650