ESP8266 Community Forum

Posted: **Fri Oct 20, 2017 4:32 pm**

I have used the ESP (NodeMCU and Wemos D1) a small amount but am not anywhere close to an expert. I want to connect a DHT11 to the board and report the temp/humidity to MQTT. I found a sketch that does exactly this and have it working, however it seems to be creating an access point and I'm not sure what line is doing that. Could someone kindly explain what I'm not seeing? I know this is not complicated, but I really can't seem to see it even though it's surely in front of my face!

The source code is from Thingsboard on github:
https://raw.githubusercontent.com/thingsboard/thingsboard.github.io/master/docs/samples/esp8266/resources/esp8266-dht-mqtt.ino

Code: Select all

#include "DHT.h"
#include <PubSubClient.h>
#include <ESP8266WiFi.h>

#define WIFI_AP "YOUR_WIFI_AP"
#define WIFI_PASSWORD "YOUR_WIFI_PASSWORD"

#define TOKEN "ESP8266_DEMO_TOKEN"

// DHT
#define DHTPIN 2
#define DHTTYPE DHT22

char thingsboardServer[] = "YOUR_THINGSBOARD_HOST_OR_IP";

WiFiClient wifiClient;

// Initialize DHT sensor.
DHT dht(DHTPIN, DHTTYPE);

PubSubClient client(wifiClient);

int status = WL_IDLE_STATUS;
unsigned long lastSend;

void setup()
{
  Serial.begin(115200);
  dht.begin();
  delay(10);
  InitWiFi();
  client.setServer( thingsboardServer, 1883 );
  lastSend = 0;
}

void loop()
{
  if ( !client.connected() ) {
    reconnect();
  }

  if ( millis() - lastSend > 1000 ) { // Update and send only after 1 seconds
    getAndSendTemperatureAndHumidityData();
    lastSend = millis();
  }

  client.loop();
}

void getAndSendTemperatureAndHumidityData()
{
  Serial.println("Collecting temperature data.");

  // Reading temperature or humidity takes about 250 milliseconds!
  float h = dht.readHumidity();
  // Read temperature as Celsius (the default)
  float t = dht.readTemperature();

  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  Serial.print("Humidity: ");
  Serial.print(h);
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(t);
  Serial.print(" *C ");

  String temperature = String(t);
  String humidity = String(h);


  // Just debug messages
  Serial.print( "Sending temperature and humidity : [" );
  Serial.print( temperature ); Serial.print( "," );
  Serial.print( humidity );
  Serial.print( "]   -> " );

  // Prepare a JSON payload string
  String payload = "{";
  payload += "\"temperature\":"; payload += temperature; payload += ",";
  payload += "\"humidity\":"; payload += humidity;
  payload += "}";

  // Send payload
  char attributes[100];
  payload.toCharArray( attributes, 100 );
  client.publish( "v1/devices/me/telemetry", attributes );
  Serial.println( attributes );

}

void InitWiFi()
{
  Serial.println("Connecting to AP ...");
  // attempt to connect to WiFi network

  WiFi.begin(WIFI_AP, WIFI_PASSWORD);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("Connected to AP");
}


void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    status = WiFi.status();
    if ( status != WL_CONNECTED) {
      WiFi.begin(WIFI_AP, WIFI_PASSWORD);
      while (WiFi.status() != WL_CONNECTED) {
        delay(500);
        Serial.print(".");
      }
      Serial.println("Connected to AP");
    }
    Serial.print("Connecting to ThingsBoard node ...");
    // Attempt to connect (clientId, username, password)
    if ( client.connect("ESP8266 Device", TOKEN, NULL) ) {
      Serial.println( "[DONE]" );
    } else {
      Serial.print( "[FAILED] [ rc = " );
      Serial.print( client.state() );
      Serial.println( " : retrying in 5 seconds]" );
      // Wait 5 seconds before retrying
      delay( 5000 );
    }
  }
}

My code which simply duplicates the 1 DHT into 2 and makes them DHT11 instead of DHT22 is:

Code: Select all

#include "DHT.h"
#include <PubSubClient.h>
#include <ESP8266WiFi.h>

#define WIFI_AP "Linksys_1"

//#define TOKEN "ESP8266_DEMO_TOKEN"

// DHT
#define DHTPIN1 D4
#define DHTPIN2 D5
#define DHTPIN3 D6
#define DHTTYPE DHT11

char MQTTServer[] = "192.168.0.200";

WiFiClient wifiClient;

// Initialize DHT sensor.
DHT dht1(DHTPIN1, DHTTYPE);
DHT dht2(DHTPIN2, DHTTYPE);
DHT dht3(DHTPIN3, DHTTYPE);

PubSubClient client(wifiClient);

int status = WL_IDLE_STATUS;
unsigned long lastSend;

int value = 0;

void setup()
{
  Serial.begin(115200);
  pinMode(DHTPIN1, INPUT_PULLUP); 
  pinMode(DHTPIN2, INPUT_PULLUP); 
  pinMode(DHTPIN3, INPUT_PULLUP); 
  dht1.begin();
  dht2.begin();
  dht3.begin();
  delay(10);
  InitWiFi();
  client.setServer( MQTTServer, 1883 );
  lastSend = 0;
}

void loop()
{
  if ( !client.connected() ) {
    reconnect();
  }

  if ( millis() - lastSend > 60000 ) { // Update and send only after 60 seconds
    getAndSendTemperatureAndHumidityData();
    lastSend = millis();
  }

  client.loop();
}

void getAndSendTemperatureAndHumidityData()
{
  ++value;

  Serial.println("Collecting temperature data.");

  // Reading temperature or humidity takes about 250 milliseconds!
  float h1 = dht1.readHumidity();
  float h2 = dht2.readHumidity();
  float h3 = dht3.readHumidity();
  // Read temperature as Celsius (the default)
  float t1 = dht1.readTemperature();
  float t2 = dht2.readTemperature();
  float t3 = dht3.readTemperature();

  // Check if any reads failed and exit early (to try again).
  if (isnan(h1) || isnan(t1)) {
    Serial.println("Failed to read from DHT1 sensor!");
  }
  else
  {
    Serial.print("Humidity1: ");
    Serial.print(h1);
    Serial.print(" %\t");
    Serial.print("Temperature1: ");
    Serial.print(t1);
    Serial.println(" *C ");

    String temperature1 = String(t1);
    String humidity1 = String(h1);

    // Just debug messages
    Serial.print( "Sending temperature1 and humidity1 : [" );
    Serial.print( temperature1 ); Serial.print( "," );
    Serial.print( humidity1 );
    Serial.print( "]   -> " );
    
    // Prepare a JSON payload string DHT1
    String payload = "";
    payload += "temperature="; payload += temperature1; payload += ",";
    payload += "humidity="; payload += humidity1;
  
    // Send payload
    char attributes[100];
    payload.toCharArray( attributes, 100 );
    client.publish( "Safe1", attributes );
    Serial.println( attributes );
  }
  
  if (isnan(h2) || isnan(t2)) {
    Serial.println("Failed to read from DHT2 sensor!");
  }
  else
  {
    Serial.print("Humidity2: ");
    Serial.print(h2);
    Serial.print(" %\t");
    Serial.print("Temperature2: ");
    Serial.print(t2);
    Serial.println(" *C ");

    String temperature2 = String(t2);
    String humidity2 = String(h2);

    // Just debug messages
    Serial.print( "Sending temperature2 and humidity2 : [" );
    Serial.print( temperature2 ); Serial.print( "," );
    Serial.print( humidity2 );
    Serial.print( "]   -> " );
    
    // Prepare a JSON payload string DHT2
    String payload = "";
    payload += "temperature="; payload += temperature2; payload += ",";
    payload += "humidity="; payload += humidity2;
  
    // Send payload
    char attributes[100];
    payload.toCharArray( attributes, 100 );
    client.publish( "Safe2", attributes );
    Serial.println( attributes );
  }
  
  if (isnan(h3) || isnan(t3)) {
    Serial.println("Failed to read from DHT3 sensor!");
  }
  else
  {
    Serial.print("Humidity3: ");
    Serial.print(h3);
    Serial.print(" %\t");
    Serial.print("Temperature3: ");
    Serial.print(t3);
    Serial.println(" *C ");

    String temperature3 = String(t3);
    String humidity3 = String(h3);

    // Just debug messages
    Serial.print( "Sending temperature3 and humidity3 : [" );
    Serial.print( temperature3 ); Serial.print( "," );
    Serial.print( humidity3 );
    Serial.print( "]   -> " );
    
    // Prepare a JSON payload string DHT3
    String payload = "";
    payload += "temperature="; payload += temperature3; payload += ",";
    payload += "humidity="; payload += humidity3;
  
    // Send payload
    char attributes[100];
    payload.toCharArray( attributes, 100 );
    client.publish( "Safe3", attributes );
    Serial.println( attributes );
  }
}

void InitWiFi()
{
  Serial.println("Connecting to AP ...");
  // attempt to connect to WiFi network

  WiFi.begin(WIFI_AP);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("Connected to AP");
}


void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    status = WiFi.status();
    if ( status != WL_CONNECTED) {
      WiFi.begin(WIFI_AP);
      while (WiFi.status() != WL_CONNECTED) {
        delay(500);
        Serial.print(".");
      }
      Serial.println("Connected to AP");
    }
    Serial.print("Connecting to MQTT server ...");
    // Attempt to connect (clientId, username, password)
    if ( client.connect("ESP8266 Device") ) {
      Serial.println( "[DONE]" );
    } else {
      Serial.print( "[FAILED] [ rc = " );
      Serial.print( client.state() );
      Serial.println( " : retrying in 5 seconds]" );
      // Wait 5 seconds before retrying
      delay( 5000 );
    }
  }
}

Posted: **Sun Oct 22, 2017 11:10 am**

I'm perplexed. I changed the code as suggested. Prior to the change, I flashed the code to a Wemos D1. The old version had an AP pop up but the new code doesn't. The NodeMCU should perform the same, but for some reason the new code doesn't keep the AP from showing up. I can't do anything with it and it's probably not an issue. I just don't understand why it's being spawned.

Posted: **Sun Oct 22, 2017 11:16 am**

Ok, well I'm embarrassed... I just flashed the basic Blink code to the NodeMCU and it still creates the AP. Clearly there's something different about it that I'm not understanding. If there's a resource for understanding this issue, a link would help. I'll start looking around to see if I can figure it out myself. This issue (code review request) is closed now.

Posted: **Sun Oct 22, 2017 11:28 am**

And now that I see there is an issue with my board with some flag, I did a search and the first link found the fix.

https://github.com/esp8266/Arduino/issues/529#issuecomment-120793753

For some reason there is still an issue with my NodeMCU in Arduino that is not setting the AP flag correctly. Adding WiFi.mode(WIFI_STA) after the WiFi.begin statement fixed it.

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