/**************************************************************************

TapeSensors.c

ME 218B Project Hats Off

Team Firefox

March 7, 2010

Robot uses 7 tape sensors to track and align with tape on the floor.

***************************************************************************/

/*-------------------------- Include Files -------------------------------*/

#include "TapeSensors.h"

typedef enum { WHITE = 0,

BLACK = 1

} TAPE_Color_t;

/*-------------------------- Module Definitions -----------------------------*/

/*-------------------------- Module Functions -----------------------------*/

/*-------------------------- Module Variables -----------------------------*/

static TAPE_Color_t lastReads[] = {0,0,0,0,0,0,0}; //1 = black, 0 = white

//keeps track of last read for each sensor for hysteresis

/*-------------------------- Module Cal Variables -------------------------*/

const static int thresWhite = 230; // white threshold = 150

const static int thresBlack = 320; // black threshold = 300

char Tape_isBlack(TAPE_Sensor_t tapeNum) {

int rawValue;

rawValue = ADS12_ReadADPin(tapeNum);

if (lastReads[tapeNum] == WHITE) {

if (rawValue > thresBlack) lastReads[tapeNum] = BLACK;

}

else {

if (rawValue < thresWhite) lastReads[tapeNum] = WHITE;

}

return (lastReads[tapeNum] == BLACK);

}

char Tape_isParallel(void) {

return (Tape_isBlack(FRONT) && Tape_isBlack(CENTER) && Tape_isBlack(REAR));

}

char Tape_isPerp(void) {

return (Tape_isBlack(CENTER) && Tape_isBlack(CENTER_LEFT) && Tape_isBlack(CENTER_RIGHT));

}

TAPE_TrackStatus_t Tape_getTrackStatus(void) {

char combo;

combo = 4*Tape_isBlack(FRONT_LEFT) + 2*Tape_isBlack(FRONT) + Tape_isBlack(FRONT_RIGHT);

switch(combo) {

case 0: return LOST; break;

case 1: return WAY_LEFT; break;

case 2: return ALIGNED; break;

case 3: return LIL_LEFT; break;

case 4: return WAY_RIGHT; break;

case 5: return ERROR; break;

case 6: return LIL_RIGHT; break;

case 7: return INTERSECTION; break;

}

}