Embedded Software

(Reviewed by Rafail)

This document describes the embedded software of the Weather Wizard. The embedded software is the code that runs on the microcontroller. The microcontroller is the brain of the Weather Wizard. It is responsible for reading the sensors, displaying the data on the LCD screen, and sending the data to the backend.

Information about the code

Program code contains comment in the top the file stating author information, license type, and goal of this part of the program and has a nice readable layout. License type is an existing license type like FreeBSD, or CC, or individual copyright (C) containing a year.

/* Author: Luca von Kannen
 * License: Apache License, version 2.0.
 * Goal: This file contains code to operate the WeatherWizard and to connect it to the backend.
 */

Code structure and syntax

Program code is indented with tabs or spaces. All code blocks contain matching opening and closing curly brackets { }. Syntax highlighting is visible.

See full code below.

Macros and constants

Program code contains no magic numbers and all macro definitions and constants are defined in one place which improves maintainability of your code.

// DHT input pin
#define DHTPIN 0   
// The DHT-11 is initialized
#define DHTTYPE DHT11 // DHT 11
DHT dht(DHTPIN, DHTTYPE);
 
//parameter for my home wifi
const char* ssid     = "Hi"; // Wi-Fi network name
const char* password = "prinsengracht225d"; // Wi-Fi network password
 
// set the LCD number of columns and rows
int lcdColumns = 16;
int lcdRows = 2;

float humidity = 0;
float temperature = 0;
int light = 0; // variable to store light intensity value

int led = 15; // GPIO pin for the LED
int light_intensity_sensor = A0; // GPIO pin for the light intensity sensor

Code documentation

All control constructs are commented. In the comments it is documented what a control construct does or why it is needed, or what decisions are made.
All functions are commented. In the comments it is documented what a function does and what it's input and output (return value) is.
Comments are easily readable and within the max character per line limits.

See full code below.

Code Reusability

There is no duplication of code.
- Libraries are used to reuse other people's program code.
- Functions are used as reusable building blocks for your own code.
- Some handy functions are placed in libraries for reuse in other applications.

See full code below. All setups and loops are in their own indepentend functions.

Naming conventions

All variables follow the camel case convention and have names reflecting the variables' use.
All macro constants (#define) are in SCREAMING_SNAKE_CASE.
All function names are in lower camel case.

/* Author: Luca von Kannen
 * License: Apache License, version 2.0.
 * Goal: This file contains code to operate the WeatherWizard and to connect it to the backend.
 */

#include <LiquidCrystal_I2C.h> // Library for interfacing with the LCD screen
#include <ESP8266WiFi.h> // Library for connecting to WiFi
#include <ESP8266HTTPClient.h> // Library for making HTTP requests
#include <WiFiClient.h>
#include <WiFiManager.h>
// Adafruit_DHT library for interfacing with the DHT11 temperature and humidity sensor
#include "DHT.h"


// DHT input pin
#define DHTPIN 0   
// The DHT-11 is initialized
#define DHTTYPE DHT11 // DHT 11
DHT dht(DHTPIN, DHTTYPE);
 
//parameter for my home wifi
const char* ssid     = "Hi"; // Wi-Fi network name
const char* password = "prinsengracht225d"; // Wi-Fi network password
 
// set the LCD number of columns and rows
int lcdColumns = 16;
int lcdRows = 2;

int buttonPin = D3; 
float humidity = 0; //variable to store the humidity
float temperature = 0; //variable to store the temperature
int light = 0; // variable to store light intensity value

int led_green = D0;
int led_red = D5; // GPIO pin for the LED
int light_intensity_sensor = A0; // GPIO pin for the light intensity sensor

bool running_ww = false; //if the Weather Wizard is currently running
String current_time = "";


// create the HTTP client object
WiFiManager wm; // Object for managing Wi-Fi connection
LiquidCrystal_I2C lcd(0x27, lcdColumns, lcdRows); // Object for interfacing with the LCD screen 
WiFiClient client; // Object for managing Wi-Fi client connection
HTTPClient httpClient; // Object for making HTTP requests

void setup() {
  //sets baud rate to 115200
  Serial.begin(115200);
  
  //wifi
  setup_wifi_manager(); // Function to set up Wi-Fi manager
  //config for lcd
  setup_lcd(); // Function to set up LCD
  setup_dht(); // Function to set up DHT11 sensor
  
  pinMode(led_red, OUTPUT); // Set LED pin to output mode
  pinMode(buttonPin, INPUT);

  //some sensors ned some time before they start working
  delay(2000); // Delay to allow sensors to stabilize
}

void loop(){


  //check if the button was pressed to turn on Weather Wizard
  button_input();

  if(running_ww){
    //get current time
    get_current_time();

    //turns on the green LED if the Weather Wizard is running
    digitalWrite(led_red, LOW);
    digitalWrite(led_green, HIGH);

  //after doing a get request the backend sends config file 
  get_config(); // Function to get configuration file from server
  //send data with a post request
  send_data(temperature, humidity, 0, 0, light); // Function to send sensor data to server
    
  run_lcd(); // Function to update LCD screen with sensor data
  read_sensors(); // Function to read sensor values


  print_to_console();
  //waits 2 sec till it makes new measurements
  delay(2000); // Delay before taking new measurements
  lcd.clear(); // Clear LCD screen
  
  }
  else{
    //turn on the red light and turn off the green light
    digitalWrite(led_red, HIGH);
    digitalWrite(led_green, LOW);
  }
}

void get_current_time() {
  
  httpClient.begin(client, "http://worldtimeapi.org/api/ip");
  int httpCode = httpClient.GET();
  
  //does a get request to receive the current time from this api
  int httpResponseCode = httpClient.GET();
  if (httpResponseCode == HTTP_CODE_OK) {
    String payload = httpClient.getString();
    int startIndex = payload.indexOf("datetime") + 12;
    int endIndex = startIndex + 19;
    current_time = payload.substring(startIndex, endIndex);
    //assign the global variable current_time to the response
  } else {
    Serial.println("HTTP request failed");
  }
}

void button_input(){
  int buttonState = digitalRead(buttonPin);

  // If the button is pressed, set running_ww to true
  if (buttonState == HIGH) {
    running_ww = true;
  } else {
    running_ww = false;
  }
}

void get_config(){
  httpClient.begin(client, "https://abc3.loca.lt/index.php?action=config"); // Set up HTTP GET request to server
  int httpCode = httpClient.GET(); // Send HTTP GET request and store response code

  if(httpCode == HTTP_CODE_OK) { // Check if response is successful
    String payload = httpClient.getString(); // Get response payload
    Serial.println(payload); // Print payload to serial monitor
  } else {
    Serial.println("Unable to connect :("); // Print error message if response is unsuccessful
  }

}


void send_data(float temperature, float humidity, float pressure, int obstacle_detected, float light_intensity) {
  // create the JSON payload string
  String payload = "{\"timestamp\":\"current_time,\"temperature\":" + String(temperature) + ",\"humidity\":" + String(humidity) + ",\"pressure\":" + String(pressure) + 
  ",\"obstacle_detected\":" + String(obstacle_detected) + ",\"light_intensity\":" + String(light_intensity) + "}";
  
  // specify the target URL
  httpClient.begin(client, "https://abc3.loca.lt/index.php?action=weather_data");
  
  // set the content type header to JSON
  httpClient.addHeader("Content-Type", "application/json");
  
  // send the POST request with the JSON payload
  int httpCode = httpClient.POST(payload);
  
  // check if the request was successful
  if (httpCode == HTTP_CODE_OK) {
    Serial.println("Data sent successfully!");
  } else {
    Serial.println("Error sending data!");
  }
  
  // free resources
  httpClient.end();
}



void read_sensors(){
  // Humidity is measured
  humidity = dht.readHumidity();
  // temperature is measured
  temperature = dht.readTemperature();
  // light
  light = analogRead(light_intensity_sensor); 
   
  // Checking if the measurements have passed without errors
  // if an error is detected, a error message is displayed here
  if (isnan(humidity) || isnan(temperature) || isnan(light)) {
    Serial.println("Error reading the sensor");
    return; //quits the function
  }
}

void print_to_console(){
    // Output to serial console
  Serial.println("-----------------------------------------------------------");
  Serial.print("Humidity: ");
  Serial.print(humidity);
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.print(char(186)); //Output <°> symbol
  Serial.println("C ");
  Serial.println("-----------------------------------------------------------");
  Serial.print("Light intensity: ");
	Serial.println( light, DEC);
  Serial.println("-----------------------------------------------------------");
}

void run_lcd(){
  lcd.setCursor(0, 0);
  lcd.setBacklight(HIGH);
  // print message
  lcd.print("Temp: ");
  
  char temp_c[5];
  lcd.print(dtostrf(temperature, 3, 2, temp_c));
  
  // set cursor to first column, second row
  lcd.setCursor(0,1);
  lcd.print("Humidity: ");
  
  char hum_c[5];
  lcd.print(dtostrf(humidity, 3, 2, hum_c));
  lcd.print("%");
}

void setup_lcd(){
  lcd.begin(5, 4);// initialize LCD
  lcd.init();
  // turn on LCD backlight                      
  lcd.backlight();
}

void setup_dht(){
  //humidity and temperture 
  Serial.println("KY-015 test - temperature and humidity test:");
  // Measurement is started
  dht.begin();
}
void connectToWiFi(const char* ssid, const char* password) {
  //this code is only needed to connect to a specific wifi
  //this method won't be called because currently the wifi manager is used
  delay(10);
  Serial.println('\n');

  WiFi.begin(ssid, password);
  Serial.print("Connecting to ");
  Serial.print(ssid);
  Serial.println("...");
  
  int i = 0;
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.print(++i);
    Serial.print(' ');
  }

  Serial.println('\n');
  Serial.println("Connection established!");
  Serial.print("IP address:\t");
  Serial.println(WiFi.localIP());
}

void setup_wifi_manager() {
  WiFiManager wifiManager; // Create a Wi-Fi manager object
  bool con = wifiManager.autoConnect("WeatherWizard AutoConnect", "password"); // Attempt to connect to Wi-Fi using saved credentials or create a new AP with the specified SSID and password
  pinMode(LED_BUILTIN, OUTPUT); // Set the built-in LED pin to output mode

  if(!con) {
      Serial.println("Failed to connect."); // Print error message if unable to connect to Wi-Fi
      digitalWrite(LED_BUILTIN, HIGH); // Turn on LED to indicate error
  } 
  else {
      Serial.println("Connected..."); // Print success message if connected to Wi-Fi
      Serial.println(WiFi.localIP()); // Print the IP address of the device
      digitalWrite(LED_BUILTIN, LOW); // Turn off LED to indicate successful connection
  }
}

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Embedded Software

Information about the code

Code structure and syntax

Macros and constants

Code documentation

Code Reusability

Naming conventions