//******************************************************************************************
//  AVR Sample Program
//   Project      :
//   Program Name :
//   Programer    :
//   Create date  :  Version 1.0    H23.09.20
//   History      :
//   Laungage     :  GCC 
//******************************************************************************************
//   Description
//    (1)Define I/O PORT
//         PB0: Voltage Reference 2.5V
//         PB1: Voltage Check 
//         PB2: Voltage Control 
//******************************************************************************************
#include <avr/io.h>
//#include <tn13adef.h>
//#include <tn13def.h>

void Int_CMPR(void);

int main(void)
{  
unsigned int lp;

// ********************
// 1.初期化
// ********************
// (1)ポートの初期化
    PORTB = 0b00000100;

// (2)コントロールポートを出力に設定
    DDRB=0x00;
    DDRB=DDRB|(1<<DDB2);

// (3)コンパレータの初期化
    Int_CMPR();

// ********************
// 2.メイン
// ********************
    while(1){
        if((ACSR & (1<<ACO))==0){
            PORTB = 0b00000000;
            for(lp=0;lp<20;lp++){
                asm("nop");
            }
            PORTB = 0b00000100;
        }
    }

}

//******************************************************************************************
//   Function Name : Int_CMPR 
//   Title         : コンパレータの初期化
//   Input         :
//   Output        :
//   Description   : 
//******************************************************************************************
void Int_CMPR(void)
{
// *********************************************************
// 1.ADCSRB(ADC Control and Status Register)
//     ADCSRB[6] ACME  : Analog Comparator Multiplexer Enable
//                    When this bit is written logic one and the ADC is switched off (ADEN in ADCSRA is zero), 
//                    the ADC multiplexer selects the negative input to the Analog Comparator. 
//                    When this bit is written logic zero, AIN1 is applied to the negative input of the Analog
//                    Comparator. 
// *********************************************************
    ADCSRB = ADCSRB & 0b10111111;

// *********************************************************
// 2.ACSR(Analog Comparator Control and Status Register) 
//      ACSR[7]  ACD:   Analog Comparator Disable
//      ACSR[6]  ACBG:  Analog Comparator Bandgap Select
//      ACSR[5]  ACO:   Analog Comparator Output
//      ACSR[4]  ACI:   Analog Comparator Interrupt Flag
//      ACSR[3]  ACIE:  Analog Comparator Interrupt Enable
//      ACSR[2]  Res:   Reserved Bit
//      ACSR[1]  ACIS1: Analog Comparator Interrupt Mode Select
//      ACSR[0]  ACIS0: Analog Comparator Interrupt Mode Select
// *********************************************************
    ACSR = (0<<ACD)|(0<<ACBG)|(0<<ACO)|(0<<ACI)|(0<<ACIE)|(0<<ACIS1)|(0<<ACIS0);

// *********************************************************
// 3.DIDR0(Digital Input Disable Register 0)
//      DIDR0[1] AIN1D: AIN1, AIN0 Digital Input Disable
//      DIDR0[0] AIN0D: AIN1, AIN0 Digital Input Disable  
//        When this bit is written logic one, the digital input buffer on the AIN1/0 pin is disabled. 
//        The corresponding PIN Register bit will always read as zero when this bit is set. 
//       When an analog signal is applied to the AIN1/0 pin and the digital input from this pin is not needed, 
//        this bit should be written logic one to reduce power consumption in the digital input buffer.
// *********************************************************
    DIDR0 = DIDR0 | (1<<AIN1D) | (1<<AIN0D);

}