How to Build an ESP8266 Based Connected Flower Monitor

#include <Wire.h>
#include <ESP8266WiFi.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>

#include "Adafruit_TSL2591.h"

#define STORAGE_SIZE 60
#define WAIT_TIME 60000

double moisture_history[STORAGE_SIZE];
double temperature_history[STORAGE_SIZE];
double humidity_history[STORAGE_SIZE];
double pressure_history[STORAGE_SIZE];
double luminosity_history[STORAGE_SIZE];

const char* ssid = "YOUR_SSID";
const char* pass = "PASSWORD";

WiFiServer server(80);
Adafruit_BME280 bme;
Adafruit_TSL2591 tsl = Adafruit_TSL2591(1);

int error = 0;
int next = 0;
long lastCapture = 0;

// Function prototypes
void findMinMaxAvg(double* res, double* input, int len);
void printArrayAsTableRow(WiFiClient c, String description, double* arr, int len);

void setup()
{
  // Open the serial monitor for debugging
  Serial.begin(9600);

  while(!Serial)
	delay(50);

  // Check whether the BME sensor is available
  if(!bme.begin())
  {
	Serial.println("Couldn't find a BME280 board!");
	error = 1;
  }

  // Configure the light sensor. These are medium settings for
  // well-lit environments. Check the official demo for more
  // configuration options and a detailed explanation.
  tsl.setGain(TSL2591_GAIN_MED);
  tsl.setTiming(TSL2591_INTEGRATIONTIME_300MS);

  Serial.println("");
  Serial.print("Connecting to ");
  Serial.print(ssid);

  // Try to connect to the supplied WiFi network
  WiFi.begin(ssid, pass);

  pinMode(A0, INPUT);
 
  while(WiFi.status() != WL_CONNECTED)
  {
	Serial.print(".");
	delay(500);
  }

  Serial.println("Done!");

  Serial.println("Starting server...");
  server.begin();
 
  Serial.print("Server started with address ");
  Serial.print("http://");
  Serial.print(WiFi.localIP());
  Serial.println("/");
}

void loop()
{
  // Check for incoming connections
  WiFiClient c = server.available();

  // Read the sensor values periodically

  double moisture_sensor_reading = 1024.0 - analogRead(A0);
  double moisture_percentage = (moisture_sensor_reading / 1024.0) * 100.0;
  double temperature = bme.readTemperature();
  double humidity = bme.readHumidity();
  double pressure = bme.readPressure() / 100.0;
  int luminosity = tsl.getLuminosity(TSL2591_VISIBLE);

  // Store the current sensor values in the historic data arrays
  // after a certain time has passed
  if(abs(millis() - lastCapture) > WAIT_TIME)
  {
	moisture_history[next] = moisture_percentage;
	temperature_history[next] = temperature;
	humidity_history[next] = humidity;
	pressure_history[next] = pressure;
	luminosity_history[next] = luminosity;

	// Reset the counter once the arrays are full
	// With the standard values, this happens every hour
	if(++next >= STORAGE_SIZE)
  	next = 0;
    
	lastCapture = millis();
  }
 
  if(c)
  {
	while(!c.available())
  	delay(10);

	// Read the first line of the HTTP request
	// It contains something similar to the following line:
	// METHOD /requested_url HTTP_VERSION
	// for example:
	// GET /index HTTP/1.1
	// However, for the sake of simplicity this device only accepts
	// GET requests as any web browser can send them.
      // Furthermore, this program ignores the requested page and it
      // always returns the same page for each request.
    
      // Read the request and empty the buffer
      // Even though we aren't interested in the request text itself
      // we should still remove the bits from the buffer.
	String request = c.readStringUntil('\r');
	c.flush();
   
	// Return the response
	// If no error occurred, send an HTML page that lists the current sensor values
	// and the historic data.
    
	if(error == 0)
	{
  	// Return a response header
  	c.println("HTTP/1.1 200 OK");
  	c.println("Content-Type: text/html");
  	// The HTTP response body is separated from the header by an empty line
  	// (actually a line containing \r\n, but this will work)
  	c.println("");

  	// Create arrays to hold the results from the
  	// accumulation operations (min, max, avg)
  	double moisture_acc[3];
  	double temperature_acc[3];
  	double humidity_acc[3];
  	double pressure_acc[3];
  	double luminosity_acc[3];

  	// Perform the accumulation operations (min, max, avg) for
  	// all historic data arrays
  	findMinMaxAvg(moisture_acc, moisture_history, next);
  	findMinMaxAvg(temperature_acc, temperature_history, next);
  	findMinMaxAvg(humidity_acc, humidity_history, next);
  	findMinMaxAvg(pressure_acc, pressure_history, next);
  	findMinMaxAvg(luminosity_acc, luminosity_history, next);
 
  	// Return the response body (an html page)
  	c.println("<html>");
  	c.println("<head>");
  	c.println("<title>IoT Flower Monitor</title>");
  	c.println("</head>");
  	c.println("<body>");
  	c.println("<h1>Current data</h1>");
  	c.println("<table border=\"1px\">");
  	c.print("<tr><td>Temperature</td><td>");
  	c.print(temperature);
  	c.println("&deg;C</td></tr>");
  	c.print("<tr><td>Humidity</td><td>");
  	c.print(humidity);
  	c.println("%</td></tr>");
  	c.print("<tr><td>Air Pressure</td><td>");
  	c.print(pressure);
  	c.println("hPa</td></tr>");
  	c.print("<tr><td>Light</td><td>");
  	c.print(luminosity > 750 ? "Bright" : (luminosity > 500 ? "OK" : (luminosity > 300 ? "Dim" : "Dark")));
  	c.println("</td></tr>");
  	c.print("<tr><td>Soil Moisture</td><td>");
  	c.print(moisture_percentage);
  	c.println("%</td></tr>");
  	c.println("</table>");
  	c.println("<h1>Historic Data</h1>");

  	// Only print the historic data if something is available
  	if(next > 0)
  	{
    	c.println("<table border=\"1\">");
    	c.println("<tr><th>Value</th><th>Min.</th><th>Max.</th><th>Avg.</th></tr>");
 	 
    	printArrayAsTableRow(c, "Temperature", temperature_acc, 3);
    	printArrayAsTableRow(c, "Humidity", humidity_acc, 3);
    	printArrayAsTableRow(c, "Air Pressure", pressure_acc, 3);
    	printArrayAsTableRow(c, "Light", luminosity_acc, 3);
    	printArrayAsTableRow(c, "Soil Moisture", moisture_acc, 3);

    	c.println("</table>");
  	}
  	// Otherwise show a warning
  	else
  	{
    	c.println("No data to display. Wait a few seconds and then reload the page!");
  	}
 	 
  	c.print("<p>Data accumulated from ");
  	c.print(next);
  	c.println(" samples.<br/>");
  	c.print("Samples taken every ");
  	c.print(WAIT_TIME / 1000.0);
  	c.print(" seconds.</p>");
  	c.println("</body>");
  	c.println("</html>");
	}
	// Otherwise, send an error message
	else
	{
  	// Return a response header
  	c.println("HTTP/1.1 500 Internal Server Error");
  	c.println("Content-Type: text/html");
  	c.println("");
  	c.println("<html>");
  	c.println("Sensor Error! Check if the sensors are connected correctly!<br/>");
  	c.println("<a href=\"/\">Back to main page</a>");
  	c.println("</html>");
	}
  }
}

void printArrayAsTableRow(WiFiClient c, String description, double* arr, int len)
{
  c.print("<tr><td>");
  c.print(description);
  c.println("</td>");

  for(int i = 0; i < len; i++)
  {
	c.print("<td>");
	c.print(arr[i]);
	c.print("</td>");
  }

  c.println("</tr>");
}

void findMinMaxAvg(double* res, double* input, int len)
{
  double maximum = -1000000;
  double minimum = 10000000;
  double sum = 0;
 
  for(int i = 0; i < len; i++)
  {
	maximum = max(maximum, input[i]);
	minimum = min(minimum, input[i]);
	sum = sum + input[i];
  }

  res[0] = minimum;
  res[1] = maximum;
  res[2] = sum / len;
}