/*
ADC1핀에 가변 저항을 연결한후, 그결과 값을 출력
*/
#include <mega128.h>
#include <delay.h>
#include <stdlib.h>

#define ENABLE  (PORTD.2=1)
#define DISABLE (PORTD.2=0)

unsigned char RESULTL=0xFF;
unsigned char RESULTH=0xFF;
volatile int adc_return=0;
unsigned char str[16];

void init_PORTD(void)
{
    DDRD = 0xFF;
    PORTD = 0xFF;
}
void wait_busy_flag(void)
{
    unsigned int i;
    for(i=0;i<10000;i++);
}
void ddelay(unsigned int p)
{
    unsigned int i;
    for(i=0;i<p;i++);
}
void instruction_out(unsigned char b)
{
    PORTD=b&0xF0; //상위 4bit 출력
    ENABLE;
    DISABLE;
    PORTD=(b<<4)&0xF0; //하위 출력
    ENABLE;
    DISABLE;
    delay_ms(2);
}   
void char_out(unsigned char b)
{
    PORTD=(b&0xF0)|0x01; //상위 4bit 출력
    ENABLE;
    DISABLE;
    PORTD=( (b<<4)&0xF0 )|0x01; //하위 출력
    ENABLE;
    DISABLE;
    delay_ms(2);
} 
void string_out(unsigned char b, unsigned char *str)
{
    unsigned int i=0;
    instruction_out(b);
    do{
    char_out(str[i]);
    }while(str[++i]!=\'\\0\');
}
void init_LCD(void)
{
    init_PORTD();
    delay_ms(15);
    ddelay(600);
    instruction_out(0x28);//LCD function set ( 16x2 line, 4bit, 5x8 dot)
    delay_ms(2); 
    instruction_out(0x28);//LCD function set ( 16x2 line, 4bit, 5x8 dot)
    delay_ms(2); 
    instruction_out(0x0C);//LCD display on, cursor off, blink off
    instruction_out(0x06);//LCD entry mode set
    instruction_out(0x02);//return home
    instruction_out(0x01);//LCD clear
    instruction_out(0x01);//LCD clear 
}

void main(void)
{  
    DDRF &= 0xFD; //ADC1 입력 
    ADMUX = 0x21;           //  결과 좌정렬, ADC1
    ADCSRA = 0xA7 ;         // 10100111  ADC 인에이블 ADC FREE RUNING MODE, 128분주
    ADCSRA  |= 0x08 ;      //ADC 인터럽트 enable 
    ADCSRA   |=  0x40;     //ADC START  
    
    init_LCD();
    
    instruction_out(0x01);
    
    #asm("sei");
    
    while (1)
     { 
       itoa(adc_return,str);
       string_out(0x80,"ADC_RESULT :");
       if(adc_return >= 100)
        string_out(0x8D,str);
       else if(adc_return >= 10 && adc_return < 100)
       {
        string_out(0x8D," ");
        string_out(0x8E,str);
        }
       else if(adc_return < 10)
       {   
        string_out(0x8D,"  ");
        string_out(0x8F,str); 
        }
      }
}           
    interrupt [ADC_INT] void adc_int(void)
    {
        #asm("cli"); 
          RESULTL = ADCL;  // 하위 8비트 READ
          RESULTH = ADCH;  //상위 비트 READ  
          adc_return=RESULTH;
        #asm("sei");
    }