//
//[lcd]       [AVR PortE]
//RS (pin4) -----  bit 0
//RD (pin 5) ----- bit 1
//EN (pin 6) ----- bit 2
//사용안함         bit 3
//DB4 (pin 11) --- bit 4
//DB5 (pin 12) --- bit 5
//DB6 (pin 13) --- bit 6
//DB7 (pin 14) --- bit 7
#include 
#include 
#include 
//
unsigned char fnd_table[10]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
unsigned int adc_value, temp=0, fnd_cnt=0;
char fnd_buf[4];
//
interrupt [TIM0_COMP] void timer0_comp_isr(void){ // 매치 인터럽트
    PORTA=0x0F;
    switch(fnd_cnt){
        case 0: PORTC=fnd_table[fnd_buf[0]]; PORTA=~1; break;
        case 1: PORTC=fnd_table[fnd_buf[1]]; PORTA=~2; break;
        case 2: PORTC=fnd_table[fnd_buf[2]]; PORTA=~4; break;
        case 3: PORTC=fnd_table[fnd_buf[3]]; PORTA=~8; break;
    }
    if(++fnd_cnt>3)fnd_cnt=0;
}
//
void main(void){
    float temp_f;
    DDRA=0x0F;  DDRC=0xFF;
    TCCR0=0x0D; OCR0=249;  TIMSK=2;  //16000000/  64/(1+249)= 1000Hz=1ms
    ADCSRA=0xE7;
    SREG=0x80;
    while(1){
        delay_ms(1);
        adc_value=ADCW;
        temp_f=(float)adc_value * 1000.0 / 1023.0;
        temp=(int)temp_f;
        fnd_buf[0]=temp/1000;
        fnd_buf[1]=(temp/100)%10;
        fnd_buf[2]=((temp/10)%10);
        fnd_buf[3]=temp%10;
    }
}