gas.c

#include <wiringPi.h>
#include <stdio.h>


typedef unsigned char uchar;
typedef unsigned int  uint;

#define     ADC_CS    0
#define     ADC_CLK   1
#define     ADC_DIO   2
#define     BEEP      3

uchar get_ADC_Result(void)
{
	//10:CH0
	//11:CH1
	uchar i;
	uchar dat1=0, dat2=0;

	digitalWrite(ADC_CS, 0);

	digitalWrite(ADC_CLK,0);
	digitalWrite(ADC_DIO,1);	delayMicroseconds(2);
	digitalWrite(ADC_CLK,1);	delayMicroseconds(2);
	digitalWrite(ADC_CLK,0);

	digitalWrite(ADC_DIO,1);    delayMicroseconds(2); //CH0 10
	digitalWrite(ADC_CLK,1);	delayMicroseconds(2);
	digitalWrite(ADC_CLK,0);

	digitalWrite(ADC_DIO,0);	delayMicroseconds(2); //CH0 0

	digitalWrite(ADC_CLK,1);
	digitalWrite(ADC_DIO,1);    delayMicroseconds(2);
	digitalWrite(ADC_CLK,0);
	digitalWrite(ADC_DIO,1);    delayMicroseconds(2);

	for(i=0;i<8;i++)
	{
		digitalWrite(ADC_CLK,1);	delayMicroseconds(2);
		digitalWrite(ADC_CLK,0);    delayMicroseconds(2);

		pinMode(ADC_DIO, INPUT);
		dat1=dat1<<1 | digitalRead(ADC_DIO);
	}

	for(i=0;i<8;i++)
	{
		dat2 = dat2 | ((uchar)(digitalRead(ADC_DIO))<<i);
		digitalWrite(ADC_CLK,1); 	delayMicroseconds(2);
		digitalWrite(ADC_CLK,0);    delayMicroseconds(2);
	}

	digitalWrite(ADC_CS,1);

	pinMode(ADC_DIO, OUTPUT);

	return(dat1==dat2) ? dat1 : 0;
}

int main(void)
{
	uchar tmp;

	if(wiringPiSetup() == -1){
		printf("setup wiringPi failed !");
		return 1;
	}

	pinMode(ADC_CS,  OUTPUT);
	pinMode(ADC_CLK, OUTPUT);
	pinMode(BEEP,    OUTPUT);
	int iter = 0;
	while(1){
		if(!(iter < 100)) {
		iter = 0;
                printf("Test? (J/N)\n");
                char input[1];
                scanf("%s",input);
                if(input[0] != 'J') {
                    break;
                }
		}
		pinMode(ADC_DIO, OUTPUT);
		tmp = get_ADC_Result();
		printf("%d\n",tmp);

		if(tmp > 100){
			digitalWrite(BEEP, 0);
			delay(500);
			digitalWrite(BEEP, 1);
			delay(500);
		}else{
			digitalWrite(BEEP, 0);
		}
		iter++;
		delayMicroseconds(2*60*1000);
	}
	digitalWrite(BEEP,0);

	return 0;
}