Table of Contents

Flood Detecton System

Alexandru Ionascu - AAC 2021
[Project Video]

1. Project Objective

This project aims to create a system that notifies owner on his smartphone about a possible flood via push notifications. This will be achieved by measuring the distance from the floor to the ultrasonic sound sensor and if it's less than 2 centimeters, it will trigger a push notification by sending a POST request to the Pushover API.

2. Project Description

The system consists in two main components: ESP32 board and HC-SR04 ultrasonic sensor.

3. Hardware Description

The hardware has two main components:

 ESP32 Wroom Board

 HC-SR04 Ultrasonic Distance Sensor
The diagram associated with the hardware will look like this:

 Hardware Diagram

4. Software Description

The code consists of two main functions: setup and loop. In the setup function, we will set the echo and trigger pins and we will connect to the local Wi-Fi network to perform further HTTP requests. Once the connection is established, in the loop function, we will measure the distance to the floor in centimeters by sending ulstrasonic impulses and if this is less than 2 centimeters, we will perform a POST request to the Pushover API. There will also be a 2s delay between requests to make avoid unnecessary push notifications.

The source code is listed below:

main.cc
#include <WiFi.h>
#include <HTTPClient.h>
 
#define SOUND_SPEED 0.034
#define CM_TO_INCH 0.393701
#define DISTANCE 2.0
 
#define PUSHOVER_URL "https://api.pushover.net/1/messages.json"
 
const int trigPin = 5;
const int echoPin = 18;
 
const char* ssid = "********";
const char* password = "********";
 
long duration;
float distanceCm;
 
void setup() {
    Serial.begin(115200);
 
    pinMode(trigPin, OUTPUT);
    pinMode(echoPin, INPUT);
 
    WiFi.begin(ssid, password);
 
    while (WiFi.status() != WL_CONNECTED) {
        delay(1000);
        Serial.println("Connecting to WiFi...");
    }
 
    Serial.println("Connected to the WiFi network");
}
 
void loop() {
    if ((WiFi.status() == WL_CONNECTED)) {
        digitalWrite(trigPin, LOW);
        delayMicroseconds(2);
 
        digitalWrite(trigPin, HIGH);
        delayMicroseconds(10);
        digitalWrite(trigPin, LOW);
 
        // Reads the echoPin, returns the sound wave travel time in microseconds
        duration = pulseIn(echoPin, HIGH);
 
        // Calculate the distance
        distanceCm = (duration * SOUND_SPEED) / 2;
 
        if (distanceCm < DISTANCE) {
            HTTPClient http;
 
            http.begin(PUSHOVER_URL);
            http.addHeader("Content-Type", "application/x-www-form-urlencoded");
 
            String form = "device=device&user=********&title=IoT - ESP32&message=Flood!!&token=********";
 
            int httpCode = http.POST(form);
 
            if (httpCode > 0) {
                String payload = http.getString();
 
                Serial.println(httpCode);
                Serial.println(payload);
            }
 
            http.end();
 
            delay(2000);
        } else {
            Serial.println("Error on HTTP request");
        }
    }
}

5. Issues and Solutions

This project had some initial issues with getting the source code up on the board, but for some reasons it got fixed once we switched from MacOS to Linux.

Another problem would be testing this application in a real life case scenario because it won't be that easy to simulate flood home.

6. Resources and Documentation

ESP32: Connecting to a WiFi network
ESP32: HTTP POST Requests
ESP32 with HC-SR04 Ultrasonic Sensor with Arduino IDE