WaterLevel

Preface

This project aims to find a tanker water level using NodeMCU with ESP8266 core and HC-SR04P Ultrasonic sensor and broadcasting it using a simple HTTP server inside NodeMCU then data can be read using a browser, android app, another NodeMCU, or anything that can create an HTTP request with GET method.

NodeMCU ESP8266 (LoLin NodeMCU V3)

Unlike generic ESP8266 models, this model offers a micro-USB connection using a CH340G (USB to serial chip) naturally soldered to ESP8266. after installing CH340G drivers and ESP8266 drivers for Arduino IDE, this chip can be programmed with Arduino compatible codes with Arduino IDE.

Specs

• 80-160MHZ RISC microprocessor
• ~128KB of RAM
• 802.11 support: b/g/n
• TCP/IP protocol stack
• ...

NodeMCU pins breakout

HC-SR04P Ultrasonic Sensor

This model is the second generation of HC-SR04 sensor, unlike the first model which only can operate at 5V DC, this new version can work with 3.3V DC too so it's perfectly safe to wire the output of this sensor directly to ESP8266 GPIO pins which operate at 0V~3.3V logic levels without using any sort of voltage divider.

Specs

• Power Supply: 3.3V~5V DC
• Effective Angle: <15 degrees
• Ranging Distance: 2cm-400cm
• Connector Pins: 4-pins header (vcc, gnd, echo, trigger)

How it works?

TL;DR Full Arduino/C++ code here

ESP8266 wifi stack offers two types, connection mode, and access point mode. in this project, we used the connection mode so ESP8266 automatically tries to connect to the station with the given SSID and password and in this project, we used a static IP for ESP8266 so we can find it more simply in the local area network.

Two sensors are wired to chip through GPIO pins, pin 12 or D6 is the trigger pin for sensor #1 and pin 14 or D5 is the echo pin for sensor #1 and pin 15 (D8) and 13 (D7) for sensor #2. each second data from both sensors is read and mapped to the new range because each sensor send distance between itself and water (something between 0cm to 170cm) so this range is better to be mapped to a more readable range like 100-0) so if the distance is 160 then the water level is almost 90 percent.

Using a simple HTTP server with port 80 data is sent for any client that tries to get data from the root of the server (http://192.168.1.100). Raw Data is like this:

T1 70% 53 T2 85% 28

Which stands for TankerName TankerPercent TankerSensorDistance.

Broweser Client

Android Client

There is a simple Android App written in Kotlin that uses OkHttp for getting sensor data and shows it in simple text and battery-like view.