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Arduino hygrometer with grafic interface

A simple Wi-Fi web hygrometer with module
ESP8266 and DHT11 / DHT22 humidity sensor.

Hygrometer with DHT11 sensor

This device is digital wifi hygrometer. It's a miniature arduino web server.
By mapping ports of your router, you can connect to it from anywhere on the world. This hygrometer uses arduino skech and
trendy vector graphics format SVG.


ESP8266 hygrometer schema



// DHT11 hygrometer with GUI ver.2.0.0
// Copyright 2017 Pavel Janko, www.fancon.cz
// MIT license, http://opensource.org/licenses/MIT
//*********************************************************************
// Add libraries DHT sensor library 1.3.0 by Adafruit and
// Adafruit Unified Sensor 1.0.2 from
// Arduino IDE - Sketch/Include Library/Manage Libraries !
const char* ssid =     "YourSSID";     // Set your router SSID
const char* password = "YourPassword"; // Set your router password
bool grade = false;   // Set scale - false = Celsius , true = Fahrenheit
#define DHTTYPE DHT11 // Set sensor type - DHT11 or DHT22
#define DHTPIN 2      // Set pin for sensor connecting
//*********************************************************************
#include <DHT.h>
#include <Ticker.h>              // For periodic events
#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>
String GradeUnit;
String buff;
float  temperature;
float  humidity;
int    FloatRounding  = 1;
float  PointerAngle;
bool   ReadSensorFlag = true;
int    SensorPeriod   = 5;       // Period of sensor reading in seconds
int    PageRefreshPeriod  = 30;  // Period of web page refresh in seconds
ESP8266WebServer server(80);
DHT dht(DHTPIN, DHTTYPE);
Ticker ReadSensorTick;           // Preparing for periodic sensor reading
void ReadSensorFlagSet(void) {   // Periodic flag setting
  ReadSensorFlag = true;
}
void setup(void) {
  if (grade) {
    GradeUnit = "F";             // Setting the temperature scale to fahrenheit
  } else {
    GradeUnit = "C";             // or celsius
  }
  Serial.begin(115200);
  WiFi.begin(ssid, password);    // Connect to router
  Serial.println("");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
  ReadSensorTick.attach(SensorPeriod, ReadSensorFlagSet); // Periodic flag setting
  //http main page
  server.on("/", HTTP_GET, []() {
    buff  = "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\"><html><head>\n";
    buff += "<meta http-equiv=\"refresh\" content=\"" + String(PageRefreshPeriod) + "\">\n";
    buff += "<title>Hygrometer</title></head><body style=\"background:silver\">\n";
    buff += "<img src=\"hygro.svg\" alt=\"Hygrometer\">\n";
    buff += "<br></body></html>\n";
    server.send(200, "text/html", buff);
  });
  // SVG picture generator
  server.on("/hygro.svg", HTTP_GET, []() {
    buff  = "<svg xmlns=\"http://www.w3.org/2000/svg\" xmlns:xlink=\"http://www.w3.org/1999/xlink\" width=\"1000\" height=\"1000\">\n";
    buff += "<circle cx=\"500\" cy=\"500\" r=\"265\" fill=\"WhiteSmoke\" stroke=\"#b46b41\" stroke-width=\"16\"/>\n";
    buff += "<circle cx=\"500\" cy=\"500\" r=\"265\" fill-opacity=\"0\" stroke=\"#c68762\" stroke-width=\"4\"/>\n";
    buff += "<g stroke=\"black\" stroke-width=\"2\" fill=\"none\">\n";
    buff += "<rect x=\"450\" y=\"590\" rx=\"5\" ry=\"5\" width=\"100\" height=\"40\"/>\n";
    buff += "<rect x=\"450\" y=\"635\" rx=\"5\" ry=\"5\" width=\"100\" height=\"40\"/></g>\n";
    buff += "<path fill=\"none\" stroke=\"#2e8b57\" stroke-width=\"20\" d=\"M413,331 A190,190 35 0 1 657,393\" />\n";
    buff += "<defs>\n";
    buff += "<g id=\"PO\">\n";
    buff += "<line stroke-width=\"5\" x1=\"500\" y1=\"500\" x2=\"500\" y2=\"700\" fill=\"orangered\"/>\n";
    buff += "<rect x=\"492\" y=\"455\" rx=\"2\" ry=\"2\" width=\"16\" height=\"64\" fill=\"orangered\"/>\n";
    buff += "<circle cx=\"500\" cy=\"500\" r=\"2\" stroke=\"brown\" stroke-width=\"4\" />\n";
    buff += "<circle cx=\"500\" cy=\"500\" r=\"3\" fill=\"grey\"/></g>\n";
    buff += "<g>\n";
    buff += "<line stroke-width=\"4\" id=\"M\" x1=\"500\" y1=\"680\" x2=\"500\" y2=\"700\"/>\n";
    buff += "<line stroke-width=\"6\" id=\"L\" x1=\"500\" y1=\"670\" x2=\"500\" y2=\"700\"/></g>\n";
    buff += "<g id=\"Z\">\n";
    buff += "<use xlink:href=\"#L\" transform=\"rotate(0,500,500)\"/>\n";
    buff += "<use xlink:href=\"#M\" transform=\"rotate(14,500,500)\"/></g></defs>\n";
    buff += "<g id=\"T\" stroke=\"black\">\n";
    buff += "<use xlink:href=\"#Z\" transform=\"rotate(40,500,500)\"/>\n";
    buff += "<use xlink:href=\"#Z\" transform=\"rotate(68,500,500)\"/>\n";
    buff += "<use xlink:href=\"#Z\" transform=\"rotate(96,500,500)\"/>\n";
    buff += "<use xlink:href=\"#Z\" transform=\"rotate(124,500,500)\"/>\n";
    buff += "<use xlink:href=\"#Z\" transform=\"rotate(152,500,500)\"/>\n";
    buff += "<use xlink:href=\"#Z\" transform=\"rotate(180,500,500)\"/>\n";
    buff += "<use xlink:href=\"#Z\" transform=\"rotate(208,500,500)\"/>\n";
    buff += "<use xlink:href=\"#Z\" transform=\"rotate(236,500,500)\"/>\n";
    buff += "<use xlink:href=\"#Z\" transform=\"rotate(264,500,500)\"/>\n";
    buff += "<use xlink:href=\"#Z\" transform=\"rotate(292,500,500)\"/>\n";
    buff += "<use xlink:href=\"#L\" transform=\"rotate(320,500,500)\"/></g>\n";
    buff += "<g font-family=\"arial\" font-size=\"36\" font-weight=\"normal\" font-style=\"normal\" stroke=\"black\" fill=\"black\" >\n";
    buff += "<text x=\"350\" y=\"685\">0</text>\n";
    buff += "<text x=\"270\" y=\"590\">10</text>\n";
    buff += "<text x=\"255\" y=\"490\">20</text>\n";
    buff += "<text x=\"290\" y=\"395\">30</text>\n";
    buff += "<text x=\"378\" y=\"315\">40</text>\n";
    buff += "<text x=\"480\" y=\"295\">50</text>\n";
    buff += "<text x=\"577\" y=\"316\">60</text>\n";
    buff += "<text x=\"660\" y=\"380\">70</text>\n";
    buff += "<text x=\"705\" y=\"490\">80</text>\n";
    buff += "<text x=\"690\" y=\"595\">90</text>\n";
    buff += "<text x=\"610\" y=\"690\">100</text>\n";
    buff += "<text x=\"450\" y=\"720\">% RH</text>\n";
    buff += "<text x=\"465\" y=\"623\" fill=\"brown\">" + String(temperature, FloatRounding) + "</text>\n";
    buff += "<text x=\"560\" y=\"620\" font-size=\"28\">" + GradeUnit + "</text>\n";
    buff += "<text x=\"465\" y=\"668\" fill=\"blue\">" + String(humidity, FloatRounding) + "</text>\n";
    buff += "<circle cx=\"560\" cy=\"595\" r=\"3\" fill=\"white\" stroke=\"black\" stroke-width=\"2\"/></g>\n";
    buff += "<g stroke=\"red\" stroke-width=\"1\" fill=\"none\">\n";
    buff += "<use xlink:href=\"#PO\" transform=\"rotate(" + String(PointerAngle) + ",500,500)\"/></g></svg>\n";
    server.send(200, "image/svg+xml", buff);
  });
  server.onNotFound (FileNotFound);          // Fast serves answer 404 File not found as a favicon.ico etc...
  server.begin();
  Serial.println("Web server started!");
}
void loop(void) {
  server.handleClient();
  if (ReadSensorFlag == true) {              // Test for periodic reading sensor
    GetTemperature();
  }
}
void GetTemperature() {
  humidity = dht.readHumidity();             // Read humidity (percent)
  temperature = dht.readTemperature(grade);  // Read temperature as Celsius or Fahrenheit
  PointerAngle = 40 + humidity * 2.8;        // Calculating angle of pointer from humidity
  Serial.print("Humidity    % :");
  Serial.println(humidity);
  Serial.print("Temperature " + GradeUnit + " :");
  Serial.println(temperature);
  Serial.println(" ");
  ReadSensorFlag = false;
}
void FileNotFound(void) {
  server.send(404, "text/plain", "Page not found !");
}

Here is Arduino sketch for download

Necessary libraries

Necessary library 1
Necessary library 2

Notes:

Jan / 2017

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