root / trunk / code / projects / linefollowing / lineFollow.c @ 1997
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/**
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* @file lineFollow.c
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* @defgroup lineFollwing Line Following
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*
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* Takes care of following a line. Running this program is done by calling the
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* init() function and then the lineFollow(speed) command. However, direct use
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* of this class is discouraged as its behavior is used by lineDrive.c, which
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* extends this class to provide behavior functionality.
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*
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* @author Dan Jacobs and the Colony Project
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* @date 11-1-2010
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*/
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#include "lineFollow.h" |
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//! The number of bits expected in a barcode
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#define CODESIZE 5 |
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#define LINE_COLOR 200 |
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/**
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* Helps with debugging.
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* 0 - no debug output.
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* 1 - print out buckets
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* 2 - print out line sensor readings
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*/
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#define DBG_LINEFOLLOW 2 |
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//! Anything lower than this value is white
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int GREY_THRESHOLD = 300; |
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//! Anything higher than this value is black
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int BLACK_THRESHOLD = 750; |
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int countHi = 0; |
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int countLo = 0; |
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int maxAvg, avg;
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// Everything has a dimension of 2 for left and right readings
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int barCode[2][ CODESIZE ]; |
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int barCodePosition[2]={0}; |
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int duration[2] = {0}; |
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int lastColor[2] = {0}; |
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char isReset[2] = {1}; |
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int lastReadings[2][ NUM_READINGS ] = {{0}}; |
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int lastReadingsPtr[2] = {0}; |
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int numLast[2][4] = { {0, 0, 0, NUM_READINGS}, {0, 0, 0, NUM_READINGS} }; |
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int bitColor[2] = {0}; |
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int turnDistance=0; |
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//! Counts the number of full line readings before we determine an intersection
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int intersectionFilter=0; |
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int disableBarCode=0; |
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//! Keeps track of where the encoder of one motor started, for use in turns.
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int encoderStart = -1; |
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int encoderReset = 0; // 0 if encoderStart has no value set |
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void lineFollow_init()
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{ |
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int i, j, curReading;
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int lowGrey = 1000, highGrey = 0, lowBlack = 1000, |
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highBlack = 0;
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analog_init(0);
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encoders_init(); |
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lost = 0;
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intersectionFilter=0;
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disableBarCode=0;
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for(i=0; i<2; i++) |
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{ |
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for(j=0; j<NUM_READINGS; j++) |
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{ |
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lastReadings[i][j] = BAD_READING; |
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} |
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isReset[i] = 1;
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} |
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// Calibrate thresholds
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orb_set_color(YELLOW); |
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delay_ms(2000);
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orb_set_color(BLUE); |
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for(i=0; i<100; i++) |
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{ |
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curReading = read_line(LEFT_SENSOR + 6);
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if(curReading < lowGrey)
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lowGrey = curReading; |
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if(curReading > highGrey)
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highGrey = curReading; |
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delay_ms(20);
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} |
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orb_set_color(YELLOW); |
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delay_ms(2000);
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orb_set_color(GREEN); |
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for(i=0; i<100; i++) |
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{ |
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curReading = read_line(LEFT_SENSOR + 6);
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if(curReading < lowBlack)
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lowBlack = curReading; |
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if(curReading > highBlack)
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highBlack = curReading; |
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delay_ms(20);
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} |
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orbs_set(0,0,0,0,0,0); |
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GREY_THRESHOLD = lowGrey / 2;
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BLACK_THRESHOLD = (highGrey + lowBlack) / 2;
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usb_puts("Grey: ");
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usb_puti(lowGrey); |
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usb_puts(", ");
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usb_puti(highGrey); |
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usb_puts("\nBlack: ");
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usb_puti(lowBlack); |
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usb_puts(", ");
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usb_puti(highBlack); |
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usb_puts("\nThresholds: ");
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usb_puti(GREY_THRESHOLD); |
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usb_puts(", ");
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usb_puti(BLACK_THRESHOLD); |
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usb_puts("\n\n");
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delay_ms(1500);
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//numLast = { {0, 0, 0, NUM_READINGS}, {0, 0, 0, NUM_READINGS} };
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} |
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/**
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* Follows a line at the given speed.
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* @param speed The speed with which to follow the line.
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*/
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int lineFollow(int speed) |
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{ |
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int colors[5]; |
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int position;
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updateLine(colors); |
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position = lineLocate(colors); |
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//not on line
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if(position == NOLINE)
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{ |
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if(lost++ > 20) |
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{ |
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orb2_set_color(GREEN); |
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motors_off(); |
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return LINELOST;
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} |
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} |
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else if(position == FULL_LINE) |
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{ |
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if(intersectionFilter++ > 4) |
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{ |
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orb2_set_color(RED); |
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barCodePosition[0]=0; |
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barCodePosition[1]=0; |
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disableBarCode=50;
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} |
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} |
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//on line
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else
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{ |
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position*=30;
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orb2_set_color(ORB_OFF); |
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motorLeft(min(speed+position, 255));
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motorRight(min(speed-position, 255));
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lost=0;
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intersectionFilter=0;
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} |
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// If we're running over a line, stop reading barcodes for a sec
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if(disableBarCode-- > 0) |
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{ |
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// Return intersection once we cross the line
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if(disableBarCode) return NOBARCODE; |
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return INTERSECTION;
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} |
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updateBarCode(); |
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return getBarCode();
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} |
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/**
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* Implements the left merge, assuming a line exists to the left. Works by
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* turning off the line at an increasing angle and waiting to hit another line
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* on the left.
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*/
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int mergeLeft()
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{ |
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motor_l_set(FORWARD, 200);
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if(turnDistance!=21)motor_r_set(FORWARD, 230); |
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else motor_r_set(FORWARD, 210); |
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int colors[5]; |
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updateLine(colors); |
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int position = lineLocate(colors);
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if(position>3 || position<-3)turnDistance++; |
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if(turnDistance>20) |
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{ |
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turnDistance=21;
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if(position<3 && position>-3) |
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{ |
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turnDistance = 0;
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return 0; |
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} |
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} |
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return 1; |
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} |
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/**
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* Implements the right merge, assuming a line exists to the right. Works by
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* turning off the line at an increasing angle and waiting to hit another line
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* on the right.
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*/
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int mergeRight()
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{ |
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motor_r_set(FORWARD, 200);
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if(turnDistance!=21)motor_l_set(FORWARD, 230); |
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else motor_l_set(FORWARD, 210); |
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int colors[5]; |
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updateLine(colors); |
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int position = lineLocate(colors);
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if(position>3 || position<-3)turnDistance++; |
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if(turnDistance>20) |
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{ |
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turnDistance=21;
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if(position<3 && position>-3) |
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{ |
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turnDistance = 0;
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return 0; |
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} |
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} |
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return 1; |
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} |
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/**
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* Turns left at a cross of two lines. Assumes that we are at lines in a cross
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* pattern, and turns until it sets straight on the new line.
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* @return 0 if turn finishes otherwise return 1
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*/
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int turnLeft()
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{ |
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/*motor_l_set(BACKWARD, 200);
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motor_r_set(FORWARD, 200);
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int colors[5];
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updateLine(colors);
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int position = lineLocate(colors);
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if(position>2 || position<-2)turnDistance++;
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if(turnDistance>1)
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{
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if(position<3 && position>-3)
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{
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turnDistance = 0;
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return 0;
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}
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}
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return 1;*/
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motor_l_set(BACKWARD,200);
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motor_r_set(FORWARD,200);
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if(!encoderReset)
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{ |
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encoderStart = encoder_get_x(RIGHT); |
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encoderReset = 1;
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} |
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if(encoder_get_x(RIGHT) < encoderStart)
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{ |
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encoderStart = 0;
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// Temporary: display an "error message" in case of overflow.
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// Using this for debugging, take it out soon!
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motor_l_set(FORWARD,0);
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motor_r_set(FORWARD,0);
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//orb_set_color(WHITE);
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delay_ms(2000);
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} |
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if(encoder_get_x(RIGHT) - encoderStart > 300) |
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{ |
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encoderReset = 0;
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return 0; |
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} |
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return 1; |
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} |
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/**
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* Turns right at a cross of two lines. Assumes that we are at lines in a cross
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* pattern, and turns until it sets straight on the new line.
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* @return 0 if the turn finishes otherwise return 1
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*/
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int turnRight()
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{ |
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motor_r_set(BACKWARD, 200);
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motor_l_set(FORWARD, 200);
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int colors[5]; |
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updateLine(colors); |
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int position = lineLocate(colors);
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if(position>2 || position<-2)turnDistance++; |
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if(turnDistance>1) |
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{ |
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if(position<3 && position>-3) |
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{ |
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turnDistance = 0;
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return 0; |
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} |
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} |
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return 1; |
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} |
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int getBarCode()
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{ |
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if(barCodePosition[1] != CODESIZE) |
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return NOBARCODE ;
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else
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{ |
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int temp = 0; |
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for(int i=0; i<CODESIZE; i++) |
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temp += (barCode[1][i] << i);
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barCodePosition[1] = 0; |
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return temp;
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} |
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} |
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void updateLine(int* values) |
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{ |
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for(int i = 0; i<5; i++) |
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values[i] = (read_line(4-i) < LINE_COLOR ? LWHITE : LBLACK);
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} |
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int lineLocate(int* colors) |
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{ |
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int i;
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int wsum = 0; |
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int count=0; |
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for(i = 0; i<5; i++) |
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{ |
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count += colors[i]/2;
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wsum += (i)*colors[i]; |
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} |
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if(count==0) |
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return NOLINE;
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if(count==5) |
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return FULL_LINE;
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return (wsum/count)-4; // Subtract 4 to center the index around the center. |
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} |
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void printBuckets(int i) |
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{ |
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int j;
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usb_puts("LP[");
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usb_puti(i); |
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usb_puts("]: ");
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usb_puti(lastReadingsPtr[i]); |
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usb_puts(", Totals: ");
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for(int j=0; j<=3; j++) |
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{ |
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usb_puts("[");
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usb_puti(j); |
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usb_puts("]: ");
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usb_puti(numLast[i][j]); |
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usb_puts(" ");
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} |
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usb_puts("\t ");
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usb_puts("\n");
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} |
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void addToBuckets(int curColor, int i) |
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{ |
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int oldest = lastReadings[i][lastReadingsPtr[i]];
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numLast[i][oldest]--; |
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lastReadings[i][lastReadingsPtr[i]] = curColor; |
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lastReadingsPtr[i] = (lastReadingsPtr[i]+1) % NUM_READINGS;
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numLast[i][curColor]++; |
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if(DBG_LINEFOLLOW == 1) |
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{ |
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printBuckets(i); |
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} |
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} |
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void updateBarCode()
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{ |
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// USING THESE GLOBAL VARIABLES
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// global int duration = 0;
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// global int lastColor = 0;
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// global int barCodePosition = 0;
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// global char isReset = 0;
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// Just uses one sensor for now
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for(int i = /*RIGHT*/LEFT_SENSOR; i <= LEFT_SENSOR; i++) |
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{ |
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// Add 6 to convert left (1) and right (0) to sensor 6 and 7
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int curReading = read_line(i + 6); |
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int curColor;
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if(curReading > BLACK_THRESHOLD)
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{ |
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curColor = LBLACK; |
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} |
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else if(curReading < GREY_THRESHOLD) |
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{ |
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curColor = LWHITE; |
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} |
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else
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{ |
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curColor = LGREY; |
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} |
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// Keep track of this reading
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addToBuckets(curColor, i); |
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// Just an error check
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if(barCodePosition[i] > CODESIZE)
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{ |
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barCodePosition[i] = 0;
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} |
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// We now edit curColor to use the majority of the last buckets.
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if(numLast[i][1] > NUM_READINGS / 2) |
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{ |
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curColor = LGREY; |
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} |
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else if(numLast[i][2] > NUM_READINGS / 2) |
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{ |
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curColor = LBLACK; |
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} |
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else if(numLast[i][0] > NUM_READINGS / 2) |
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{ |
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curColor = LWHITE; |
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duration[i]++; |
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} |
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else
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{ |
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curColor = BAD_READING; |
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} |
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// Print out the current reading and label, if in debug mode
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if(DBG_LINEFOLLOW == 2) |
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{ |
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switch(curColor)
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{ |
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case LBLACK: usb_puts("LBLACK.\t"); break; |
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case LGREY: usb_puts("LGREY.\t\t"); break; |
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case LWHITE: usb_puts("LWHITE.\t\t\t"); break; |
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} |
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usb_puti(curReading); |
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usb_puts("\n");
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} |
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if(curColor != BAD_READING)
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{ |
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// Now we assume our reading is significant - a bit, or a white space
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if(bitColor[i] == LGREY || bitColor[i] == LWHITE)
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bitColor[i] = curColor; |
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// Only read a value if we have read 0 first (isReset == 1)
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if(isReset[i] && (curColor == LBLACK || curColor == LGREY) )
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{ |
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isReset[i] = 0;
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duration[i] = 0;
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} |
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else if(curColor == LWHITE) |
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{ |
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if(!isReset[i])
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{ |
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barCode[i][barCodePosition[i]++] = |
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(bitColor[i] == LBLACK) ? 1 : 0; |
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usb_puts("Reset. Read bit: ");
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usb_puts(((bitColor[i] == LBLACK) ? "BLACK" : "GREY")); |
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usb_puts("\t");
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usb_puts(((curColor==LWHITE) ? "LWHITE" : "NOTWHITE")); |
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usb_puts("\n");
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|
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bitColor[i] = LWHITE; |
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} |
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isReset[i] = 1;
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orb_set(0, 0, 0); |
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} |
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} |
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|
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if(curColor == LWHITE && duration[i] > TIMEOUT_DURATION
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&& barCodePosition[i] != 0)
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{ |
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usb_puts("TIMED OUT. BARCODE READER RESET.\n");
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usb_puts("Encoders: ");
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usb_puti(encoder_get_dx(LEFT)); |
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usb_puts(", ");
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usb_puti(encoder_get_dx(RIGHT)); |
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usb_puts("\n");
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barCodePosition[i] = 0;
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duration[i] = 0;
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isReset[i] = 1;
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} |
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} |
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} |
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|
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|
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int min(int x, int y){return x>y ? y : x;} |
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int max(int x, int y){return x<y ? y : x;} |
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|
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void motorLeft(int speed){ |
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((speed-=127)>=0)?motor_l_set(FORWARD, 160+speed*95/128):motor_l_set(BACKWARD, 160-speed*95/127); |
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} |
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|
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void motorRight(int speed){ |
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((speed-=127)>=0)?motor_r_set(FORWARD, 160+speed*95/128):motor_r_set(BACKWARD, 160-speed*95/127); |
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} |