ESP8266 at Instruction Set

ESP8266 at Instruction Set

ESP8266 at Instruction Set

Flashing an ESP8266 with Espruino

Flashing an ESP8266 with Espruino by Kolban Technical Tutorials

https://github.com/nodemcu/nodemcu-flasher
https://github.com/espruino/EspruinoBuilds/tree/master/ESP8266

DHT11 sensor data to Thingspeak using a Wemos D1

In this example we will connect a DHT11 sensor to our Wemos D1, we will then send the temperature and humidity values to thingspeak.

Wemos_D1_ESP8266

DHT11 digital temperature and humidity sensor is a composite Sensor contains a calibrated digital signal output of the temperature and humidity. Application of a dedicated digital modules collection technology and the temperature and humidity sensing technology, to ensure that the product has high reliability and excellent long-term stability. The sensor includes a resistive sense of wet components and an NTC temperature measurement devices, and connected with a high-performance 8-bit microcontroller.

Typically a DHT11 can be bought in a basic breakout board format but can be bought as a standalone part as well, here is a picture of a typical breakout board, this board holds the sensor and a resistor, the resistor is connected between Vdd (3v3) and the signal pin on the board.

dht11 breakout

If you do not use a module like the one aboveyou can build a similar circuit on a breadboard. Here is a typical schematic, which is basically what the breakout above actually is

 

Dht11_application

You will connect the Gnd of the module (DHt11) to a Gnd on your Wemos board, connect 5v or Vdd of the module (DHt11) to a 3v3 connection on your Wemos and the Sig pin (data pin on the DH11) goes to whatever input you decide to use on your Wemos, in the code below you can see this as

#define DHTPIN 2

 

You will now need to create a new account at thingspeak – https://thingspeak.com. Once done create a new channel and add two new fields, one will hold the temperature reading and the other will hold the humidity reading from our DHT11. This should look something like this

thingspeak channel
thingspeak channel

 

Code

You will need an api key from thingspeak.

#include <DHT.h>
#include <ESP8266WiFi.h>
 
// replace with your channel’s thingspeak API key and your SSID and password
String apiKey = "thingspeak api key";
const char* ssid = "ssid name";
const char* password = "ssid password";
const char* server = "api.thingspeak.com";
 
#define DHTPIN D2
#define DHTTYPE DHT11 
 
DHT dht(DHTPIN, DHTTYPE);
WiFiClient client;
 
void setup() 
{
Serial.begin(115200);
delay(10);
dht.begin();
 
WiFi.begin(ssid, password);
 
Serial.println();
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
 
WiFi.begin(ssid, password);
 
while (WiFi.status() != WL_CONNECTED) 
{
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
 
}
 
void loop() 
{
 
float h = dht.readHumidity();
float t = dht.readTemperature();
if (isnan(h) || isnan(t)) 
{
Serial.println("Failed to read from DHT sensor!");
return;
}
 
if (client.connect(server,80)) {
String postStr = apiKey;
postStr +="&field1=";
postStr += String(t);
postStr +="&field2=";
postStr += String(h);
postStr += "\r\n\r\n";
 
client.print("POST /update HTTP/1.1\n");
client.print("Host: api.thingspeak.com\n");
client.print("Connection: close\n");
client.print("X-THINGSPEAKAPIKEY: "+apiKey+"\n");
client.print("Content-Type: application/x-www-form-urlencoded\n");
client.print("Content-Length: ");
client.print(postStr.length());
client.print("\n\n");
client.print(postStr);
 
Serial.print("Temperature: ");
Serial.print(t);
Serial.print(" degrees Celsius Humidity: ");
Serial.print(h);
Serial.println("Sending data to Thingspeak");
}
client.stop();
 
Serial.println("Waiting 20 secs");
// thingspeak needs at least a 15 sec delay between updates
// 20 seconds to be safe
delay(20000);
}

Results

If you login to your thingspeak account you can view live channel data, here is an iframe of some data from my test

Wemos webserver example

In this example we will create a basic webserver example using our Wemos, it will connect to your Wifi network and then you will navigate to a URL and a basic page will appear. This page will display 2 links , one will switch on an led connected to D5 and the other option will switch the led off.

Wemos D1 ESP8266 based board
Wemos D1 ESP8266 based board

Parts

1 x Wemos D1 or D2
1 x USB cable
1 x LED and resistor or use a module

Code

#include <ESP8266WiFi.h>
 
const char* ssid = "ssid name";
const char* password = "ssid password";
 
int ledPin = D5;
WiFiServer server(80);
 
void setup() {
  Serial.begin(115200);
  delay(10);
 
 
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);
 
  // Connect to WiFi network
  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
 
  WiFi.begin(ssid, password);
 
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");
 
  // Start the server
  server.begin();
  Serial.println("Server started");
 
  // Print the IP address
  Serial.print("Use this URL : ");
  Serial.print("http://");
  Serial.print(WiFi.localIP());
  Serial.println("/");
 
}
 
void loop() {
  // Check if a client has connected
  WiFiClient client = server.available();
  if (!client) {
    return;
  }
 
  // Wait until the client sends some data
  Serial.println("new client");
  while(!client.available()){
    delay(1);
  }
 
  // Read the first line of the request
  String request = client.readStringUntil('\r');
  Serial.println(request);
  client.flush();
 
  // Match the request
 
  int value = LOW;
  if (request.indexOf("/LED=ON") != -1) {
    digitalWrite(ledPin, HIGH);
    value = HIGH;
  } 
  if (request.indexOf("/LED=OFF") != -1){
    digitalWrite(ledPin, LOW);
    value = LOW;
  }
 
 
 
  // Return the response
  client.println("HTTP/1.1 200 OK");
  client.println("Content-Type: text/html");
  client.println(""); //  do not forget this one
  client.println("<!DOCTYPE HTML>");
  client.println("<html>");
 
  client.print("Led pin is now: ");
 
  if(value == HIGH) {
    client.print("On");  
  } else {
    client.print("Off");
  }
  client.println("<br><br>");
  client.println("Click <a href=\"/LED=ON\">here</a> turn the LED on pin 5 ON<br>");
  client.println("Click <a href=\"/LED=OFF\">here</a> turn the LED on pin 5 OFF<br>");
  client.println("</html>");
 
  delay(1);
  Serial.println("Client disconnected");
  Serial.println("");
 
}

Results

Open the serial monitor , all going well and you will see the IP address and messages like the following

wemos ip address
wemos ip address

Using your favourite web browser navigate to the IP above

wemos browser
wemos browser

 

 

Update

I tried this out and it uses a static IP address

//This example will set up a static IP - in this case 192.168.1.99
 
#include <ESP8266WiFi.h>
 
const char* ssid = "ssid name";
const char* password = "ssid password";
 
int ledPin = D5;
WiFiServer server(80);
IPAddress ip(192, 168, 1, 99); // where xx is the desired IP Address
IPAddress gateway(192, 168, 1, 1); // set gateway to match your network
 
void setup() {
  Serial.begin(115200);
  delay(10);
 
 
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);
 
  Serial.print(F("Setting static ip to : "));
  Serial.println(ip);
 
  // Connect to WiFi network
  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
  IPAddress subnet(255, 255, 255, 0); // set subnet mask to match your network
  WiFi.config(ip, gateway, subnet); 
  WiFi.begin(ssid, password);
 
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");
 
  // Start the server
  server.begin();
  Serial.println("Server started");
 
  // Print the IP address
  Serial.print("Use this URL : ");
  Serial.print("http://");
  Serial.print(WiFi.localIP());
  Serial.println("/");
 
}
 
void loop() {
  // Check if a client has connected
  WiFiClient client = server.available();
  if (!client) {
    return;
  }
 
  // Wait until the client sends some data
  Serial.println("new client");
  while(!client.available()){
    delay(1);
  }
 
  // Read the first line of the request
  String request = client.readStringUntil('\r');
  Serial.println(request);
  client.flush();
 
  // Match the request
 
  int value = LOW;
  if (request.indexOf("/LED=ON") != -1) {
    digitalWrite(ledPin, HIGH);
    value = HIGH;
  } 
  if (request.indexOf("/LED=OFF") != -1){
    digitalWrite(ledPin, LOW);
    value = LOW;
  }
 
 
 
  // Return the response
  client.println("HTTP/1.1 200 OK");
  client.println("Content-Type: text/html");
  client.println(""); //  do not forget this one
  client.println("<!DOCTYPE HTML>");
  client.println("<html>");
 
  client.print("Led pin is now: ");
 
  if(value == HIGH) {
    client.print("On");  
  } else {
    client.print("Off");
  }
  client.println("<br><br>");
  client.println("Click <a href=\"/LED=ON\">here</a> turn the LED on pin 5 ON<br>");
  client.println("Click <a href=\"/LED=OFF\">here</a> turn the LED on pin 5 OFF<br>");
  client.println("</html>");
 
  delay(1);
  Serial.println("Client disconnected");
  Serial.println("");
 
}