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

#define DHTPIN 7
#define MAXTIMING 85

int data[5] = {0,0,0,0,0};
char buff[20];

int read_dht11(){

	uint8_t laststate = HIGH;
	uint8_t counter = 0;
	uint8_t i = 0, j = 0;
	float f;

	data[0] = data[1] = data[2] = data[3] = data[4] = 0;

	pinMode(DHTPIN, OUTPUT);
	digitalWrite(DHTPIN, LOW);
	delay(18);
	digitalWrite(DHTPIN, HIGH);
	delayMicroseconds(40);
	pinMode(DHTPIN, INPUT);

	for(i=0;i<MAXTIMING;i++){

		counter = 0;

		while(digitalRead(DHTPIN) == laststate){
			
			counter++;
			delayMicroseconds(1);
			if(counter == 255){
				break;
			}
		}

		laststate = digitalRead(DHTPIN);

		if(counter == 255){
			break;
		}

		if((i >= 4) && (i % 2 == 0)){
			data[j/8] <<= 1;
			if(counter > 16){
				data[j/8] |= 1;
			}
			j++;
		}

	}

	if((j >= 40) && (data[4] == ((data[0] + data[1] + data[2] + data[3]) & 0xFF))){

		f = data[2] * 9. / 5. + 32;
		printf("Humidity = %d.%d %%, Temperature = %d.%d *C (%.1f *F)\n",
			data[0], data[1], data[2], data[3], f);
		
		FILE* f;
		f = fopen("result.csv", "w");

		time_t now = time(NULL);
		strftime(buff, 20, "%Y%m%d%H%M%S", localtime(&now));

		if(data[2] > 50){
			return;
		}

		fprintf(f, "%s,%d.%d,%d.%d\n", buff, data[0], data[1], data[2], data[3], f);

		fclose(f);
		return 1;

	}else{
		printf("failed..\n");
	}

	return 0;
	

}


int main(){

	if(wiringPiSetup() == -1){
		printf("error");        
	}

	while(!read_dht11()){
		delayMicroseconds(500 * 1000);
	}

}