Alin-Constantin Paun
Published © GPL3+

Wireless weather station (Arduino + ESP8266 + Thingspeak)

Ever wondered how much CO level is in your city air? How about the temperature and humidity around you? If so, welcome to this project page!

IntermediateFull instructions provided5 hours23,251
Wireless weather station (Arduino + ESP8266 + Thingspeak)
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Things used in this project

Hardware components

Arduino UNO
Arduino UNO
×1
M1201 step down converter DC-DC 3-40V to 1.25-35V
×1
Mini-360 step down converter DC-DC 4.75V-23V to 1V-17V
×1
DHT11 Temperature & Humidity Sensor (4 pins)
DHT11 Temperature & Humidity Sensor (4 pins)
×1
Carbon Monoxide (CO) Sensor - MQ-7
×1
ESP8266 ESP-12E
Espressif ESP8266 ESP-12E
×1
SparkFun Logic Level Converter - Bi-Directional
SparkFun Logic Level Converter - Bi-Directional
×1
5V Low Level Trigger 1 Channel Relay Module
×1
Pushbutton switch 12mm
SparkFun Pushbutton switch 12mm
×1
Basic On/Off DC Switch
×1
LED (generic)
LED (generic)
×6
Buzzer
Buzzer
×1
USB-A to Micro-USB Cable
USB-A to Micro-USB Cable
×1
1N4007 – High Voltage, High Current Rated Diode
1N4007 – High Voltage, High Current Rated Diode
×2
Resistor 10k ohm
Resistor 10k ohm
×3
Jumper wires (generic)
Jumper wires (generic)
×1

Software apps and online services

Arduino IDE
Arduino IDE
ThingSpeak API
ThingSpeak API

Hand tools and fabrication machines

Soldering iron (generic)
Soldering iron (generic)
Hot glue gun (generic)
Hot glue gun (generic)
Electric file
Multimeter

Story

Read more

Custom parts and enclosures

DHT 11 lib

MQ-7 Datasheet

Schematics

Schematic PNG

Fritzing schematics

Code

Main Code

C/C++
#include<stdlib.h>
#include "DHT.h"

//-----ESP8266 macros---------
#define SSID "------"//your network name
#define PASS "------"//your network password
#define IP "184.106.153.149" // thingspeak.com
#define Baud_Rate 9600 //Another common value is 115200
#define GREEN_LED 3 //optional LED's for debugging
#define RED_LED 4 //optional LED's for debugging
#define YELLOW_LED 5 //optional LED's for debugging
#define ESP_FOUND_LED 6 //optional LED's for debugging
#define DELAY_TIME 3000 //time in ms between posting data to ThingSpeak

//Can use a post also
String GET = "GET /update?key=------";
//String FIELD1 = "&field1=";
String FIELD2 = "&field2=";
String FIELD3 = "&field3=";

bool updated;

//----Relay/MQ-7 macros
#define RELAY 8
#define MQ7_ANALOG_IN_PIN 0
#define HEATING_LED 9
#define READING_LED 10
#define BUZZER 11

#define MQ7_HEATER_5_V_TIME_MILLIS 60000
#define MQ7_HEATER_1_4_V_TIME_MILLIS 90000
#define GAS_LEVEL_READING_PERIOD_MILLIS 1000

unsigned long startMillis;
unsigned long switchTimeMillis;
unsigned int gasLevel;
boolean heaterInHighPhase;

//----Temperature sensor macros
#define DHTPIN 7     // what pin the DHT sensor is connected to
#define DHTTYPE DHT11   // Change to DHT22 if that's what you have

DHT dht(DHTPIN, DHTTYPE);

//this runs once
void setup()
{
  //initalize DHT sensor
  dht.begin();

  //start the clock
  startMillis = millis();

  //initialize network LEDs
  pinMode(GREEN_LED, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(YELLOW_LED, OUTPUT);
  pinMode(ESP_FOUND_LED, OUTPUT);


  //initialize MQ-7 LEDs
  pinMode(HEATING_LED, OUTPUT);
  pinMode(READING_LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  //initialize MQ-7 power supply
  pinMode(RELAY, OUTPUT);

  //set baud rate
  Serial.begin(Baud_Rate);
  delay(1000);

  //-----connect to network---------
  Serial.println("Checking if ESP8266 is online...");
connectionStart:
  Serial.println("AT");
  delay(5000);

  if (Serial.find("OK")) {
    digitalWrite(ESP_FOUND_LED, HIGH);
    Serial.println("ESP8266 found <module online>...");
    Serial.println("Trying to connect to network...");
    //connect to your wifi netowork
    bool connected = false;

    do {
      networkBlinkConnecting();

      connected = connectWiFi();

      if (!connected) //signal failure
        for (int i = 0; i < 3; i++)
          networkBlinkError();
    } while (!connected);

    Serial.println("Connection achived....");
    digitalWrite(YELLOW_LED, HIGH); // indicate connection achived

  } else {
    Serial.println("ESP8266 not found...");
    Error();
    goto connectionStart;
  }

}

//this runs over and over
void loop() {

  if (heaterInHighPhase) {
    // 5v phase of cycle. see if need to switch low yet
    if (millis() > switchTimeMillis) {
      Serial.println("Reading from sensors....");
      turnHeaterLow();
    }
    blinkHeating();
  }
  else {
    // 1.4v phase of cycle. see if need to switch high yet
    if (millis() > switchTimeMillis) {
      Serial.println("Heating the gas sensor....");
      turnHeaterHigh();
    }

    // Read temperature and humidity
    float h = dht.readHumidity();
    float f = dht.readTemperature(false);
    unsigned int gasLevel = readGasLevel();
    blinkReading();

    // Check if any reads failed and exit early (to try again).
    if (isnan(h) || isnan(f) || isnan(gasLevel)) {
      networkBlinkError();
      return;
    }
    else if (gasLevel >= 60) {
      tone(BUZZER, 3000); // Send 1KHz sound signal...
    }
    else {
      noTone(BUZZER);     // Stop sound...
    }

    //update ThingSpeak channel with new values
    updated = updateValues(String(f), String(h), String(gasLevel));

    //if update succeeded light up green LED, else light up red LED
    Serial.println(updated);
    if (updated) {
      networkBlinkSending();
    } else {

      networkBlinkError();
    }

    blinkReading();
  }
}

//----network update function--------------
bool updateValues(String temp, String humid, String gasLevel) {

  //initialize your AT command string
  String cmd = "AT+CIPSTART=\"TCP\",\"";

  //add IP address and port
  cmd += IP;
  cmd += "\",80";

  //connect
  Serial.println(cmd);
  delay(500);

  if (Serial.find("Error")) {
    return false;
  }

  //build GET command, ThingSpeak takes Post or Get commands for updates, I use a Get
  cmd = GET;
  //cmd += FIELD1;
  cmd += temp;
  cmd += FIELD2;
  cmd += humid;
  cmd += FIELD3;
  cmd += gasLevel;

  cmd += "\r\n";

  //Use AT commands to send data
  Serial.print("AT+CIPSEND=");
  Serial.println(cmd.length());
  if (Serial.find(">")) {
    //send through command to update values
    Serial.print(cmd);
  } else {
    Serial.println("AT+CIPCLOSE");
  }

  if (Serial.find("OK")) {
    //success! Your most recent values should be online.
    return true;
  } else {
    return false;
  }
}

//----network functions--------------
boolean connectWiFi() {
  //set ESP8266 mode with AT commands
  Serial.println("AT+CWMODE=1");
  delay(2000);

  //build connection command
  String cmd = "AT+CWJAP=\"";
  cmd += SSID;
  cmd += "\",\"";
  cmd += PASS;
  cmd += "\"";

  //connect to WiFi network and wait 5 seconds
  Serial.println(cmd);
  delay(5000);

  //if connected return true, else false
  if (Serial.find("OK")) {
    return true;
  } else {
    return false;
  }
}

void Error() {
  networkBlinkError();
  Serial.println("Error");
}

//----MQ-7 functions--------------

void blinkHeating() {
  digitalWrite(HEATING_LED, HIGH);
  delay(200);
  digitalWrite(HEATING_LED, LOW);
  delay(200);
}

void blinkReading() {
  digitalWrite(READING_LED, HIGH);
  delay(GAS_LEVEL_READING_PERIOD_MILLIS / 2);
  digitalWrite(READING_LED, LOW);
  delay(GAS_LEVEL_READING_PERIOD_MILLIS / 2);
}
//--read from gas sensor---------
unsigned int readGasLevel() {
  return analogRead(MQ7_ANALOG_IN_PIN);
}

//----network LEDs--------

void networkBlinkSending() {
  digitalWrite(RED_LED, LOW);
  digitalWrite(GREEN_LED, HIGH);
  delay(500);
  digitalWrite(GREEN_LED, LOW);
  delay(500);
}

void networkBlinkError() {
  digitalWrite(GREEN_LED, LOW);
  digitalWrite(RED_LED, HIGH);
  delay(200);
  digitalWrite(RED_LED, LOW);
  delay(200);
}

void networkBlinkConnecting() {
  digitalWrite(YELLOW_LED, HIGH);
  delay(200);
  digitalWrite(YELLOW_LED, LOW);
  delay(200);
}

//--- relay logic
void turnHeaterHigh() {
  // 5v phase
  digitalWrite(RELAY, HIGH);
  heaterInHighPhase = true;
  switchTimeMillis = millis() + MQ7_HEATER_5_V_TIME_MILLIS;
}

void turnHeaterLow() {
  // 1.4v phase
  digitalWrite(RELAY, LOW);
  heaterInHighPhase = false;
  switchTimeMillis = millis() + MQ7_HEATER_1_4_V_TIME_MILLIS;
}

Credits

Alin-Constantin Paun
1 project • 11 followers
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Related channels and tags
  • Arduino
  • Espressif
  • SparkFun
  • ThingSpeak
  • Weather
  • Weather