/*
  Firmware for current sensor, the 89S52 Project Board.
  The sensor is tied to analog input channel1.
  Channel0 is available for experimenting with another sensors.

  Copyright (C) 2007, Wichit Sirichote, kswichit@kmitl.ac.th
 
*/

#include<reg52.h>
#include<stdio.h>

float read_temp1(void);
float read_temp1_filter(void);


sbit ADCDATA = P1^4;
sbit CS = P3^6;
sbit CLK = P2^4;
sbit LEDDATA = P3^7;
sbit STROBE = P2^5;
sbit LED = P1^2;

char segment[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x39};

int timer3, timer4;
char cputick;
char buffer[4];
unsigned int x1,x2,x3,x4,x5,x6,x7,x8,x9,x10;
unsigned int temp1;

int read_current(void);


// return 12-bit ADC data 0 - 4095
int read_ADC(char n)
{				
	char i,channel;	  	
	int k;
	k=0;
	CS=0;
	if(n==0) channel=0x0d;
	else channel=0x0f;

	for(i=0;i<4;i++)
	{
		CLK = 0;
		if(channel&8) ADCDATA = 1;
		else ADCDATA = 0;
		CLK = 1;
		channel <<=1;
	}
		ADCDATA = 1;
		CLK = 0;

	for(i=0;i<12;i++)
	{
		k<<=1;
		CLK=1;
		CLK=0; 
		if(ADCDATA) k|=1;
		else k&=~1;
	}
		CS = 1;
	return k&0xfff;
}

// write 32-bit data to CMOS shift register 4094
void write_led()
{	
	char m,n;
	for(n=0;n<4;n++)
	{
		for(m=0;m<8;m++)
		{
			if(buffer[n]&0x80) LEDDATA=1;
			else LEDDATA=0;
			CLK =1;
			buffer[n]<<=1;
			CLK =0;
		}
	}
	STROBE=1;	// strobe all 32-bit to the output
	;
	STROBE=0;
}


// display temperature in celcius
void update()
{
		
		//temp1=read_temp1_filter()*10;
		//temp1=(low_pass_filter1());   // display temperature in F degrees
		temp1 = read_current();
		buffer[0]=segment[temp1/1000];
		temp1=temp1%1000;
		buffer[1]=segment[temp1/100];
		temp1 = temp1%100;
		buffer[2]=segment[temp1/10];
		buffer[3]=segment[temp1%10];
	
}



/*

// display ADC raw data 0-4095 for 0 to +5V input at channel 0
// select below function when calibrating the input sensor! 
void update()
{
		
		temp1=read_ADC(1);
		buffer[0]=segment[temp1/1000];
		temp1=temp1%1000;
		buffer[1]=segment[temp1/100];
		temp1= temp1%100;
		buffer[2]=segment[temp1/10];
		buffer[3]=segment[temp1%10];
	
}

*/

// print temperature to display
  
void print_ADC()
{
	if(++timer3>10)
	{
		timer3=0;
		update();
		write_led();   	
	}
} 

// toggle LED every 50 ticks
void blinkLED()
{
    if(++timer4>50)
	{
	 timer4 = 0;
	 LED ^= 1;
	 }
	 
}

// return filtered data using 5-point moving average
int low_pass_filter1(void)
{
    x10=x9;
    x9=x8;
    x8=x7;
	x7=x6;
	x6=x5;
	x5=x4;
	x4=x3;
	x3=x2;
	x2=x1;
	x1=read_ADC(1);
	return(x1+x2+x3+x4+x5+x6+x7+x8+x9+x10)/10;
}

int read_current()
{
   int i;
   float k=0;
  // for(i=0; read_ADC(1)<10 && i<100; i++)
  // continue;

   for (i=0; i<256; i++)
   {
     k+= read_ADC(1);
	 }
   //return k/256;
   k/= 256;
   k*= .010;	// LSB for 30A range
   return 220*k;   // return WATT 220Vrms x Irms
}

//3.4A  0.411V  337 ADC
// 1LSB 3.4A/337 = .010 



// return calibrated temperature in celcius
float read_temp1_filter(void)
{
	return(0.0323*low_pass_filter1()-15.122);
}

 void timer0int(void) interrupt 1 using 1
{
 TH0 = 0xd8; // reload value for 100Hz produced by 12MHz XTAL
 TL0 = 0xf0; //	for 11.0592MHz, reload value = 0xDC00
 cputick++;
}

void main()
{
	EA=1;
	ET0=1;
	TMOD|=0x01;
	TR0=1;
	cputick =0;

	while(1)
	{
	while(!cputick)
	 continue;
	 cputick = 0;
     // below tasks will be executed every 10ms
	 print_ADC();
     blinkLED();
	
	}
}