main.c

#include "i2c.h"
#include <stdio.h>

#define READ 1
#define WRITE 0
#define threshold 250.0		// unit : lux

//*******************************************************************************************//
//								Automatic-Solar-Tracking-System                              //
//									Author : Chen-Ting Li                                    //
//						MCU : 8051, Servo Motor : SG90, Sensor : BH1750                      //
//							1. Self-defined IIC protocol for BH1750 (i2c.c/.h)               //
//						2. Using Timer2 to generate PWM signal for servo motor               //
//*******************************************************************************************//

// Declartion of BH1750 variable 
volatile unsigned char rdata_h=0;
volatile unsigned char rdata_l=0;
volatile unsigned char receive;
volatile int count=0;
volatile unsigned char tracking=0;
volatile unsigned char check_ti=0;
volatile unsigned char check_ri=0;
volatile float sunlight;

// Declartion of servo motor variable 
sbit pwm_out=P1^0;
volatile unsigned char pin_state;
volatile unsigned long duty_cycle;


void delay_2s(void){
 	#pragma asm
	delay_2:
		MOV R5,#100
	aaaa:
		MOV R6,#0FFH
	bbbb:
		MOV R7,#0FFH
	cccc:
		DJNZ R7,cccc
		DJNZ R6,bbbb
		DJNZ R5,aaaa
		RET
	#pragma endasm
}

void TIMER_INIT(){
	//setting timer 2 as PWM
	T2CON=0x00; 	// auto-reload, timer mode, TR2=0
	RCAP2H=TH2=(unsigned char)((65536-duty_cycle)>>8);
	RCAP2L=TL2=(unsigned char)((65536-duty_cycle) & 0xFF);
	//setting timer 1 this is uart baudrate
	TMOD=0x21;
	TH1=217;
	TL1=217;
	//setting uart
	SCON=0x50;
	AUXR2|=0x40;

	//setting timer 0 this is how long enter the interrupt
	TH0=0x15;
	TL0=0x9f;		//60ms enter interrupt
	TF0=0;
	TR0=1;
	TR1=1;
	PS=1;
	ET0=1;
	ES=1;
	ET2=1;
	EA=1;
}

void PWM_INIT(){
	duty_cycle=1500;
	P1M1 |= 0x01;
	P1M0 &= ~(0x01);
	pwm_out=1;
	pin_state=1;
	TR2=1;
}

void CLEAR_GY302_LASTDATA(){
	START();
	WRITE_ADDRESS(35,WRITE);
	WRITE_OPECODE(1);
	STOP();
	delay_2_4_us();
	START();
	WRITE_ADDRESS(35,WRITE);
	WRITE_OPECODE(7);
	STOP();
	delay_120ms();
}

void GET_GY302(){
	START();
	WRITE_ADDRESS(35,WRITE);
	WRITE_OPECODE(1);
	STOP();
	delay_2_4_us();
	START();
	WRITE_ADDRESS(35,WRITE);
	WRITE_OPECODE(32);
	STOP();
	delay_120ms();
	START();
	WRITE_ADDRESS(35,READ);
	READ_DATA(&rdata_h,&rdata_l);
	STOP();
}

void SERVO(unsigned char angle){
	unsigned long temp;
	if(angle>180) angle=180;
	temp=((unsigned long)angle*100+4)/9 +500;
	EA=0;
	duty_cycle=temp;
	EA=1;
}

void SERVO_INITPOS(unsigned char angle){
	SERVO(angle);
	delay_2s();
}

void TRACKINGv2() {
    float sunlight_pre = 0;					// save the previous sunlight data
    static int angle_per_step = 90;			// servo motor initial position (unit:degree)
    static int direction = 1;				// rotating direction for decision strategy
	int step=2;								// rotating angle per step
    GET_GY302();						
    sunlight = (rdata_h * 256 + rdata_l) / 1.2;
    sunlight_pre = sunlight; 
    while (sunlight < threshold) {
        angle_per_step += (step*direction);
        
		// to avoid the rotating angle out of the range
        if (angle_per_step > 180) { angle_per_step = 180; direction = -1; }		
        if (angle_per_step < 0)   { angle_per_step = 0;   direction = 1; }
        
        SERVO((unsigned char)angle_per_step);
        delay_120ms();        
		
		// update the sensor data and send to user by serial port
        rdata_h = 0; rdata_l = 0;
        GET_GY302();
        sunlight = (rdata_h * 256 + rdata_l) / 1.2;
        SBUF=rdata_h;
		delay_120ms();
		SBUF=rdata_l;
		delay_120ms();
		
		// the decision for rotating direction
        if (sunlight < sunlight_pre && (sunlight_pre-sunlight)>3.0) {
            direction = -direction; 
        }
        // update sunlight_pre
        sunlight_pre = sunlight;
		
        if (sunlight >= threshold) break; 
        delay_120ms();
    }
}

void main(){
	PORT_INIT();
	TIMER_INIT();
	PWM_INIT();
	SERVO_INITPOS(90);
	while(1){
		if(tracking==1){
			tracking=0;
			TRACKINGv2();
		}
	}
}

void timer0() interrupt 1{
	TH0=0xD8;		// every 10000us(10ms, 0.01sec) enter this ISR
	TL0=0xEF;
	count++;
	if(count==1000){
		count=0;
		tracking=1;
	}
}

void uart() interrupt 4{
	if(TI==1){
		TI=0;
		check_ti=1;
	}
	else {
		RI=0;
		check_ri=1;
		receive=SBUF; 
		}
} 

void timer2() interrupt 5{
	TF2=0;
	if(pin_state==1){
		pin_state=0;
		pwm_out=0;
		TH2=(unsigned char)((65536-duty_cycle)>>8);
		TL2=(unsigned char)((65536-duty_cycle) & 0xFF);
	}else{
		pin_state=1;
		pwm_out=1;
		TH2=(unsigned char)((65536-duty_cycle)>>8);
		TL2=(unsigned char)((65536-duty_cycle) & 0xFF);
	}
}