/*
        ADC.C

        LCD connected to Port B :
	
                 PB7 PB6 PB5 PB4 PB3 PB2 PB1 PB0
                 D7  D6  D5  D4  EN  RS  NC  NC

        ADC connected to Port D :
		 
                 PD6    PD5     PD4     PD3     PD2     PD1     PD0
                 CS     SCLK    DIN     DOUT    BUSY    NC      NC
	 
        The R/W pin of LCD is connected to ground, because we will never
        read any data from LCD, we will always write into it.
*/

#include <sfr2313.h>
#include <stdlib.h>
#include <standard.h>

void init_lcd () ;
void display_lcd () ;
void lcd_cmd1 (unsigned char) ;	
void lcd_cmd (unsigned char) ;
void lcd_dat1 (unsigned char) ;
void lcd_dat (unsigned char) ;

#define	TRUE        1
#define	FALSE       0

unsigned char index ;
unsigned long int ind ;
unsigned int cw ;
char	lcd_buff[33] = "1:              2:              " ;
unsigned char count;                    
unsigned int mask, adc_value ;
unsigned int divisor, mask1 ;
char negative, overflow ;

void init_lcd() {
        lcd_cmd1((unsigned char)3);
        delay(6000);                    /*4.5 ms*/ // assuming 4 MHZ crystal
        lcd_cmd1((unsigned char)3);
        delay(200);                     /*200 micro sec*/
        lcd_cmd1((unsigned char)3);
        delay(200);                    /*200 micro sec*/

        lcd_cmd((unsigned char)0x28);  /*DL=0:4 bit;N=1:2 line,F=0:5x7*/
        lcd_cmd((unsigned char)8);     /*display, cursor, blinking off*/
        lcd_cmd((unsigned char)0x0c);  /*display on*/
        lcd_cmd((unsigned char)6);     /*entry mode set increment*/
}
void display_lcd () {
/*
        sends lcd_buff to display
*/
        lcd_cmd(0x80);       // cursor set to first line first char position
        for(count= 0 ; count < 32; count++) {
                if(count == 16) {
                lcd_cmd((unsigned char)0xc0) ;
                // cursor to second line first char position
                }
                if(lcd_buff[count]) lcd_dat(lcd_buff[count]);
                else lcd_dat(' ') ;
        }
}
void lcd_cmd (unsigned char tempchar) {
/*
        This function sends the contents of global variable 'tempchar'
        as a command to LCD
*/
        lcd_cmd1((tempchar / (unsigned char)16));   // MS nibble
        lcd_cmd1((tempchar & (unsigned char)0x0f)); // LS nibble
        delay(200) ;
}
void lcd_cmd1 (unsigned char data) {
/*
        sends the 4 LSBits of Acc. as a (half) command to the LCD
*/
        PORTB = (data << (unsigned char) 4) & (unsigned char) 0xf0 ;
        // A0 and CS low
        PORTB |= (unsigned char) 8 ;    // CS high
        PORTB &= (unsigned char) 0xf7 ; // CS low
}
void lcd_dat1 (unsigned char data) {
        PORTB = ((data << (unsigned char) 4) & (unsigned char) 0xf0) | (unsigned char) 0x04 ;
        // A0 high and CS low
        PORTB |= (unsigned char) 8 ;    //CS high
        PORTB &= (unsigned char) 0xf7;  // CS low
}
void lcd_dat (unsigned char tempchar) {
/*
        This function sends the contents of global variable 'tempchar'
        as data to LCD
*/
  lcd_dat1((tempchar / (unsigned char)16)) ;
  lcd_dat1((tempchar & (unsigned char)0xf)) ;
  delay(200) ;
}
unsigned char check_for_ready () {
        for(ind = 0 ; ind < 0xffff ; ind++) {
                 if ((PIND & (unsigned char)4)) return TRUE ;
        }
         return FALSE ;
}
oid read_adc (unsigned int control_word) {
	adc_value = 0 ;
	if (!check_for_ready()) return ;
	// check the busy status - TRUE -> ok
	delay(0xffff) ;		// a big delay
	
	PORTD &= (unsigned char) 0xbf ;			// cs - chip select low - start conversion
	mask = 0x8000 ;
	
	for(index = 0 ; index < 16 ; index++)	{
	 // SCLK - high		
	 if(control_word & mask) PORTD |= (unsigned char) 0x10 ;	// place data
	 else PORTD &= (unsigned char) 0xef ;
	 PORTD |= (unsigned char) 0x20 ;				// sclk = 1 
	 adc_value = (adc_value << 1) ;
	 if((PIND & (unsigned char)8)) adc_value |= 1 ;	// read data
	 mask >>= 1 ; 
	 // SCLK - low
	 PORTD &= (unsigned char) 0xdf ;	// sclk
	}
	PORTD |= (unsigned char) 0x40 ; // cs - chip select high
	if (adc_value & 0x4000) overflow = 'E' ;
	else overflow = ' ' ;
	adc_value &= mask1  ;
	if(adc_value & 0x8000) {
		adc_value = -(adc_value | ((~mask1) & 0xf000)) ;
//	  adc_value = -(adc_value | 0x7000) ;	
	  negative = '-' ;
	  if (overflow == ' ') overflow = 'E' ;
	  else overflow = ' ' ;
	}
	else negative = ' ' ;
	adc_value = (adc_value * 2500ul) / divisor ;
}



void main() {
        DDRB = 0xff ;   // define PORTB as output
        DDRD = 0x70 ;   // define PORTD pins direction
        init_lcd();     // initialise the LCD display

    cw1=0x8c80;     //control word for channel1
    cw2=0x8c90;     //control word for channel2
    divisor=16384;
    mask1=0xbfff;

	read_adc(cw1 | 0x0c) ; //offset correction
	read_adc(cw1 | 0x8) ;  //gain caliberation
	read_adc(cw1 | 4) ;    //offset null

        delay(0xffff);

	read_adc(cw2 | 0x0c) ; //offset correction
	read_adc(cw2 | 0x8) ; //gain caliberation
	read_adc(cw2 | 4) ;   //offset null



        while(1) {
                read_adc(cw) ;
                ultoa(adc_value, lcd_buff+19, 5) ;
                lcd_buff[18] = negative ;
                lcd_buff[31] = overflow ;
                read_adc(cw|0x10) ;
                ultoa(adc_value, lcd_buff+3, 5) ;
                lcd_buff[2] = negative ;
                lcd_buff[15] = overflow ;
                display_lcd() ;  
                delay(0xffff) ;  // some delay
         }
}