/*
  Firmware for Thermistor sensor input, 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];
int x1,x2,x3,x4,x5;
unsigned int temp1;


// 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=(read_temp1_filter()*9/5+32)*10;   // display temperature in F degrees
		buffer[0]=segment[temp1/100];
		temp1=temp1%100;
		buffer[1]=segment[temp1/10];
		buffer[1]|=0x80;   // put decimal point
		buffer[2]=segment[temp1%10];
		buffer[3]=segment[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)
{
	x5=x4;
	x4=x3;
	x3=x2;
	x2=x1;
	x1=read_ADC(1);
	return(x1+x2+x3+x4+x5)/5;
}

// 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();
	
	}
}