Water level monitor project

Arduino Ethernet Wiznet W5100 / W5500 ESP8266 ESP32 Ultrasonic HC-SR04 JSN-SR04T PHY Ethernet WiFi

---

Supported microcontrollers for Water Level monitor - AVR / ESP

---

---

Transmission technology modules - Ethernet

---

---

Compatible ultrasonic distance sensors

---

---

Water Level monitor - Arduino / ESP8266 / ESP32

---

Water level monitor project consists of a central web interface that serves to collect data from sensor nodes and visualize them to the user. Current data on the water level are represented in the dashboard together with the conversion to the volume of the well, historical data on the water level are also available to the user in tabular or graphical visualization with line graphs. Web interface is responsive, it can adapt to any screen and device resolution. Project's web interface uses a backend written in PHP that can process incoming data from the request using the HTTP POST method. Backend corrects the measured level to the actual one based on the known depth of the well, calculates the volume of water in the well from this parameter and the diameter of the well. Depth and diameter of the well are entered into the system by the user based on the proportions of his well. Data is sent to the web server by a microcontroller supported by technology (Ethernet / WiFi / IoT networks LoRaWAN / Sigfox / NB-IoT), which performs measurements every 300 seconds - i. 5 minutes. Water level measurement is performed using ultrasonic sensors - HC-SR04, or its waterproof variant JSN-SR04T. Other sensors with Trigger / Echo signals from the RCW, US-XXX, IOE-SR0X, SR0X, HC-SR0X, HY-SRF0X, DYP-MEXXX, Parallax PING)))™ series can also be used.

Principle of measuring ultrasonic sensors is to send a Trigger signal with a length of 10 μs (microseconds), which bounces off the water level and returns to the receiver - Echo. Time-of-Flight method is used to recalculate the time between sending and receiving the signal to determine the distance of the water level from the sensor, which is located at the top of the well. Conversion formula takes into account the speed of sound 343 m/s at a temperature of 20 °C. An important parameter for both ultrasonic sensors is the beam width, in other words the detection characteristic. HC-SR04 sensor has a 15° detection characteristic. The beam is relatively narrow and the sensor is also suitable for narrower wells and tanks, but it is not waterproof and has a high risk of corrosion (oxidation) due to the presence of moisture in the well. For this reason, it is advisable to place this ultrasonic sensor above the well. Waterproof sensor JSN-SR04T has a detection characteristic of 60°, which considerably limits it and prevents its use in narrow wells, as the beam widens with distance and requires a well with a diameter of several meters (6 meters diameter at a well depth of 4.5 meters) . Ultrasonic sensors are fully maintenance-free. The JSN-SR04T sensor has an electronic control board that must not be exposed to moisture and water. Standard communication shielded cable is 2.5 meters long, it is possible to connect counterparts of the same cable to extend the line. In the case of a square well, the diameter of the inscribed circle is entered into the average, which will form the reference value of the water cylinder for the calculation of the well volume. Error of the total well volume in this case will be at the level of ~12.5%. The maximum measurable level height (level) by the sensors is about 400 to 450 cm (known from the datasheet).

---

Video demonstration of the web interface - Water Level monitor:

---

---

Ultrasonic sensors are suitable for:

---

---

Ultrasonic sensors are NOT suitable for:

---

---

Plug n' play firmware - Ultra Low Power / StandBy

---

---

WiFi network configuration via WiFiManager - Plug n' play firmware

---

---

Principle of water level measurement and data transmission - Block diagram

---

Backend at web interface uses trigonometry to estimate the measurable maximum depth of a well at a known well diameter (another parameter for calculating well volume). Wnterface allows the user to calculate to what maximum depth of the well each of the sensors is suitable based on its characteristics. Project is so easy to use even for laymen who do not know which sensor is more suitable for application in their well. Microcontroller used also plays an important role in the system. For the project, it is possible to use the Arduino platform (Uno / Mega) in revision R3 with an identical pinout, which can be connected to an Ethernet shield that communicates via the ICSP interface. It is also possible to use Ethernet modules and connect them directly to the hardware SPI pins of the microcontroller. Ethernet modules from Wiznet W5100, W5500, USR-ES1 are supported. From manufacturer MicroChip there is supported module ENC28J60 with software TCP stack. All Ethernet modules provide HTTP connectivity with the web server - port 80. WiFi microcontrollers from Espressif Systems - ESP8266 and ESP32 are also supported. Microcontrollers have several operating modes: StandBy, StandBy + OTA with the possibility of remote firmware upload via LAN network and deep sleep mode for ULP applications - Deep Sleep. In sleep mode for the ESP8266 microcontroller, it is necessary to add a physical jumper between GPIO16 (WAKE) and RST - see Wiring Diagram. ESP microcontrollers also allow to implement encrypted communication with the web server via HTTPS protocol. ESP32 saab kasutada ka PHY Etherneti mooduliga LAN8720 RMII liidese kaudu, toetab HTTP ja HTTPS ühendust. Both the ESP8266 and ESP32 platforms use the Root CA, which has issued a certificate (Issuer) for the web server domain. Certificate is embedded in the source code of the microcontrollers in .pem format. In order for the certificate not to take up space in the RAM memory of the microcontroller, it is inserted into the flash memory of the microcontroller - PROGMEM. Certificate of the certification authority is valid for 10 to 20 years, so it does not require frequent renewal of the certificate. Data on the current water level and water volume in the well are available in JSON format from the web interface. Water level monitor project can be integrated via MQTT into home automation (Hassio, Domoticz, Loxone) to display the water level in its own dashboard, e.g. Grafana, Ubidots, Thingsboard, Cayenne. Subsequently, it is possible to perform peripheral control in the subsystem (irrigation, watering, activation of the domestic waterworks) on the basis of data on the water level in the well from the web interface.

---

Available libraries for microcontrollers (Arduino / ESP)

---

---

Screenshots of Water Level monitor webapp

---

---

UART output of sensor nodes - FreeRTOS - ESP32:

---