Maneesha.a.k
Published © GPL3+

Raspberry PI Based IoT Project Connecting DHT11 Sensor

The goal of this tutorial is to enable you to capture and send data to cloud from your Raspberry Pi.

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Raspberry PI Based IoT Project Connecting DHT11 Sensor

Things used in this project

Hardware components

Raspberry Pi 3 Model B
Raspberry Pi 3 Model B
×1
DHT11 Temperature & Humidity Sensor (4 pins)
DHT11 Temperature & Humidity Sensor (4 pins)
×1

Software apps and online services

thingsio.ai
ThingsIO.AI is an IoT Platform to Connect, Control, Analyze the sensor data.

Story

Read more

Schematics

Raspberry pi and DHT11 connection diagram

Code

Raspberry pi and DHT11 sensor code

C/C++
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <netinet/in.h>
#include <netdb.h>
#include <time.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdint.h>
#include <wiringPi.h>

#define MAXTIMINGS	85
#define DHTPIN		7
int dht_data[5] ={0,0,0,0,0};

int main(void)
{
	int sockfd,n,sz,result;
	int port_no=80;
	char buffer[512];
	char post[256];
	struct sockaddr_in serv_addr;
	struct hostent *server;
	char host_name[]= "api.thingsio.ai"; //host name
	char url[]= "/devices/deviceData";  //url
	errno=0;
	
	wiringPiSetup();
	int8_t laststate	= HIGH;
	uint8_t counter		= 0;
	uint8_t j		= 0, i;
	char Temp[10];
	char Humi[10]; 
 
	dht_data[0] = dht_data[1] = dht_data[2] = dht_data[3] = dht_data[4] = 0;
 
		
	while(1) //infinite loop
	{
	pinMode(DHTPIN, OUTPUT); //define pin as a output pin
	digitalWrite(DHTPIN, LOW); // define pin to write the data as low
	delay(18);
	
	digitalWrite(DHTPIN, HIGH); // define pin to write the data as low
	delayMicroseconds(40);
	
	pinMode(DHTPIN, INPUT); //define pin as a input pin
	
	for (i=0;i<MAXTIMINGS;i++)
	{
		counter = 0;
		while (digitalRead(DHTPIN)==laststate)
		{
			counter++;
			delayMicroseconds(1);
			if (counter == 255) //run counter till 255
			{
				break;
			}
		}
		laststate = digitalRead(DHTPIN); //read the pin and store in last state
 
		if (counter == 255) //again run counter till 255
			break;
 
		if ( (i >= 4) && (i % 2 == 0) ) //ignore the first three transitions
		{
			dht_data[j / 8] <<= 1;
			if ( counter > 50 )
				dht_data[j / 8] |= 1;
			j++;
		}
	}
	//verfy the checksum and print the data
		if ( (j >= 40) && (dht_data[4] == ( (dht_data[0] + dht_data[1] + dht_data[2] + dht_data[3]) & 0xFF) ) )
	{
		
		printf( "Humidity = %d.%d %% Temperature = %d.%d *C\n",
			dht_data[0], dht_data[1], dht_data[2], dht_data[3]);
			
		sprintf(Humi,"%d.%d",dht_data[0],dht_data[1]); //print and store the string value in Humi
		sprintf(Temp,"%d.%d",dht_data[2],dht_data[3]); //print and store the string value in Temp
        
        printf("------------------Time Stamp--------------------------\n");		
		time_t currtime;
		time(&currtime);
		struct tm* utctime = gmtime(&currtime);
		result = mktime(utctime);
		printf("%d\n",result); //timestamp value
	
        printf("-------------------------------------------------\n");		
		//store the post data in json format
		sprintf(post,"{\n" "\"device_id\": 201873,\n" "\"slave_id\": 2,\n" 
					"\"dts\": %d,\n" "\"data\" : \n" "{\n" "\"Humi\": %s,\n" 
					"\"Temp\": %s\n" "}\n" "}",result,Humi,Temp);
		printf("%s\n",post); //print the post data
		
		sockfd = socket(AF_INET, SOCK_STREAM, 0);// create an endpoint for communication
		if(sockfd<0)
		{
			printf("\nfailed socket %s",strerror(errno));
			return -1;
		}
		printf("\nSocket successfull");
	
		server = gethostbyname(host_name); //retrieves host information corresponding to a host name from a host database
	
		if(server==NULL)
		{
			printf("\nfailed get host by name %s",strerror(errno));
			return -1;
		}
		printf("\ngot host by name");
		
	//erases  the  data  in the n bytes of the memory
      // starting at the location pointed to by serv_addr by writing zeroes
		bzero((char *) &serv_addr, sizeof(serv_addr));
		
	//structure which contains code for the address family	
		serv_addr.sin_family = AF_INET;
		
	//copy byte sequence	
		bcopy((char *)server->h_addr,(char *)&serv_addr.sin_addr.s_addr,server->h_length);
		
	// converts a port number in host byte order to a port number in network byte order	
		serv_addr.sin_port = htons(port_no);
		
		printf("\nconnecting to the server");
	
	//initiate the connection on a socket
		if(connect(sockfd,(struct sockaddr *) &serv_addr, sizeof(serv_addr))<0)
		{
		printf("\n connection failed %s",strerror(errno));
		return -1;
		}
	
		printf("\nServer successfully connected\n");
	
	// store the HTTP post request into buffer
		sprintf(buffer,"POST %s HTTP/1.1\n" 
					"Host: %s\n" 
					"Content-Type: application/json\n"
					"Cache-Control: no-cache\n"
					"Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.IjViNjJiNWM3NTVkMWIwNWVlNzBmY2VkYSI.L_XS9MtsZyQRfsC3N2GqXdpgrrdb2f-hQbNf81dNPx0\n"
					"Content-Length: %d\n\n"
					"%s",url,host_name,strlen(post),post);
	
		n=send(sockfd,buffer,sizeof(buffer),0);//send the HTTP post request
		if(n<0)
		{
			printf("\nbuffer not send");
		}
		printf("\n--------------------------------------------------\n");
		printf("\n buffer send\n");
		bzero(buffer,512);
		
		//waiting the response from the server 
		// receive and print response
		while((sz=recv(sockfd,buffer,511,0))>0)
		{
			buffer[sz]='\0';
			printf("%s\n",buffer);
		}
	
		printf("\n");
		close(sockfd);//close the connection
		sleep(30);
	}else  {
		printf( "Data not good, skip\n" );
	}
}

		return 0;
	}

Credits

Maneesha.a.k

Maneesha.a.k

6 projects • 20 followers
pursuing masters degree in electronics, things cloud technologies pvt ltd, internshala students partner

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Related channels and tags
  • Raspberry Pi
  • Sensors