photosensor.c

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/*
 * photo sensor control
 *
 * (c) 2007 by Matthias Arndt <matthias.arndt@tu-clausthal.de>
 *
 * control lines P3.3 - P3.7
 * analogue input P1.0
 *
 * 10kHz pulses generated via Timer 1
 */
#include "t89c51cc02.h"
#include "datatypes.h"
#include "photosensor.h"
#include "adc.h"
#include "sharp.h"
#include <stdlib.h>

BYTE psensor;

const char psensor_select[]={0,0x08,0x10,0x20,0x40,0x80,0,0};

void Photosensor_init()
{
        ADCF |= 0x01;   /* select P1.0 for analogue input */
        psensor=0;
        Photosensor_PowerOff();
}

void Photosensor_toggle(void)
{
        /* blink sender LED of selected photo sensor */
        switch(psensor)
        {
        case 1:
                P3_3=!P3_3;
                break;
        case 2:
                P3_4=!P3_4;
                break;
        case 3:
                P3_5=!P3_5;
                break;
        case 4:
                P3_6=!P3_6;
                break;
        case 5:
                P3_7=!P3_7;
                break;
        default:
                /* disable photo sensors when no valid sensor has been selected */
                Photosensor_select(0);
                Photosensor_PowerOff();
        }

}       

WORD Photosensor_read(BYTE sensornr)
{
        WORD diff1,diff2;
        
        Photosensor_select(sensornr);
        SHARP_PWRCTL=0;         /* ensure Sharp is powered off so it won't give false readings */
        /* now we read the sensor 2 times once with pulse and once without */
        diff1=ADC(0);   /* read */
        Photosensor_PowerOff();
        diff2=ADC(0);

        return(abs(diff1-diff2));
}

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