Circuit Documentation

Summary

This circuit is designed to monitor and control the watering of soil using a NodeMCU V3 ESP8266 microcontroller. It includes two soil moisture sensors to measure the moisture level of the soil at different depths, an HC-SR04 ultrasonic sensor to monitor the water level in a reservoir, and a water pump to irrigate the soil when necessary. The system is powered by a 5V battery and is capable of activating an alarm if the water level is too low.

Component List

NodeMCU V3 ESP8266

• Description: A WiFi-enabled microcontroller based on the ESP8266 chip.
• Pins: A0, GND, VU, S3, S2, S1, SC, S0, SK, 3V3, EN, RST, Vin, D0, D1, D2, D3, D4, D5, D6, D7, D8, RX, TX

Soil Moisture Sensor (x2)

• Description: A sensor that measures the volumetric water content of the soil.
• Pins: VCC, GND, SIG

HC-SR04 Ultrasonic Sensor

• Description: A sensor that uses ultrasonic sound waves to measure distance.
• Pins: VCC, TRIG, ECHO, GND

5V Battery

• Description: A power source for the circuit.
• Pins: Positive, Negative

Water Pump

• Description: A pump used for moving water to irrigate the soil.
• Pins: VCC, GND

Wiring Details

NodeMCU V3 ESP8266

• A0: Connected to Soil Moisture Sensor SIG pins
• GND: Common ground with Soil Moisture Sensors, HC-SR04 Ultrasonic Sensor, Water Pump, and 5V Battery Negative
• Vin: Connected to 5V Battery Positive
• D1: Connected to Soil Moisture Sensor VCC
• D2: Connected to Soil Moisture Sensor VCC
• D5: Connected to HC-SR04 Ultrasonic Sensor TRIG
• D6: Connected to HC-SR04 Ultrasonic Sensor ECHO
• D7: Connected to Water Pump VCC
• 3V3: Connected to HC-SR04 Ultrasonic Sensor VCC

Soil Moisture Sensor

• VCC: Connected to NodeMCU V3 ESP8266 D1 or D2
• GND: Common ground with NodeMCU V3 ESP8266 and other components
• SIG: Connected to NodeMCU V3 ESP8266 A0

HC-SR04 Ultrasonic Sensor

• VCC: Connected to NodeMCU V3 ESP8266 3V3
• TRIG: Connected to NodeMCU V3 ESP8266 D5
• ECHO: Connected to NodeMCU V3 ESP8266 D6
• GND: Common ground with NodeMCU V3 ESP8266 and other components

5V Battery

• Positive: Connected to NodeMCU V3 ESP8266 Vin
• Negative: Common ground with NodeMCU V3 ESP8266 and other components

Water Pump

• VCC: Connected to NodeMCU V3 ESP8266 D7
• GND: Common ground with NodeMCU V3 ESP8266 and other components

Documented Code

// Soil Moisture Sensor Pins and Variables
#define topSoilVcc D1          // GPIO pin to power the top soil sensor
#define bottomSoilVcc D2       // GPIO pin to power the bottom soil sensor
#define soilMoisturePin A0     // Analog pin to read moisture level (shared by both sensors)
int topMoistureValue;          // Store moisture sensor value for the top soil
int bottomMoistureValue;       // Store moisture sensor value for the bottom soil
int moistureThreshold = 300;   // Threshold value for soil moisture

// Ultrasonic Sensor Pins and Variables
#define trigPin D5             // Trig pin of Ultrasonic Sensor
#define echoPin D6             // Echo pin of Ultrasonic Sensor
long duration;
int distance;
int waterLevelThreshold = 20;  // Set threshold for low water level in cm

// Water Pump Pin
#define pumpRelay D7           // Relay module controlling the pump

// Alarm Pin (Buzzer or LED for low water alert)
#define alarmPin D8            // Alarm pin for low water level

// Timing Variables
unsigned long previousMillis = 0;  // Store the last time sensor was checked
const long interval = 10800000;    // 3 hours interval in milliseconds (10800000)

// Total Water Used Calculation
int pumpIterations = 0;            // Number of times the pump has been activated

void setup() {
  Serial.begin(9600);

  // Pin modes
  pinMode(pumpRelay, OUTPUT);
  digitalWrite(pumpRelay, LOW);  // Ensure pump is initially off
  
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  pinMode(alarmPin, OUTPUT);
  digitalWrite(alarmPin, LOW);   // Ensure alarm is initially off

  // Set soil sensor VCC control pins as outputs
  pinMode(topSoilVcc, OUTPUT);
  pinMode(bottomSoilVcc, OUTPUT);

  // Ensure both sensors are initially off
  digitalWrite(topSoilVcc, LOW);
  digitalWrite(bottomSoilVcc, LOW);
}

// Function to read top soil moisture level
int readTopSoilMoisture() {
  digitalWrite(bottomSoilVcc, LOW);    // Ensure bottom sensor is off
  digitalWrite(topSoilVcc, HIGH);      // Power the top soil sensor
  delay(500);                          // Give time for sensor to stabilize
  int value = analogRead(soilMoisturePin);  // Read the value from analog pin
  digitalWrite(topSoilVcc, LOW);       // Turn off the top soil sensor
  return value;
}

// Function to read bottom soil moisture level
int readBottomSoilMoisture() {
  digitalWrite(topSoilVcc, LOW);       // Ensure top sensor is off
  digitalWrite(bottomSoilVcc, HIGH);   // Power the bottom soil sensor
  delay(500);                          // Give time for sensor to stabilize
  int value = analogRead(soilMoisturePin);  // Read the value from analog pin
  digitalWrite(bottomSoilVcc, LOW);    // Turn off the bottom soil sensor
  return value;
}

// Function to read water level using the ultrasonic sensor
int readWaterLevel() {
  // Send a trigger pulse
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read echo time
  duration = pulseIn(echoPin, HIGH);

  // Calculate the distance in cm
  int distance = duration * 0.034 / 2;
  Serial.print("Water level distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  return distance;
}

// Function to activate the pump for watering
void activatePump() {
  Serial.println("Turning on the water pump...");
  digitalWrite(pumpRelay, HIGH);  // Turn on the pump
  delay(10000);                   // Pump water for 10 seconds
  digitalWrite(pumpRelay, LOW);   // Turn off the pump
  pumpIterations++;               // Count the pump cycle
  Serial.println("Pump turned off.");
}

// Function to check water level and raise alarm if low
bool checkWaterLevelAndAlarm() {
  int waterLevel = readWaterLevel();
  if (waterLevel > waterLevelThreshold) {
    Serial.println("Water level is too low! Raising alarm...");
    digitalWrite(alarmPin, HIGH);  // Turn on alarm (Buzzer or LED)
    return false;  // Break the loop and stop watering
  } else {
    Serial.println("Water level is sufficient.");
    digitalWrite(alarmPin, LOW);   // Turn off alarm
    return true;  // Continue with the process
  }
}

// Main loop function
void loop() {
  // Timing control: Check every 3 hours
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= interval) {
    previousMillis = currentMillis;
    pumpIterations = 0;  // Reset pump iteration count for this cycle

    // Read the soil moisture levels
    topMoistureValue = readTopSoilMoisture();
    bottomMoistureValue = readBottomSoilMoisture();
    Serial.print("Top Soil Moisture Level: ");
    Serial.println(topMoistureValue);
    Serial.print("Bottom Soil Moisture Level: ");
    Serial.println(bottomMoistureValue);

    // Check if either top or bottom soil moisture is below the threshold
    if (topMoistureValue < moistureThreshold || bottomMoistureValue < moistureThreshold) {
      Serial.println("Moisture level is below threshold, checking water level...");

      // Continue watering while either sensor is below the threshold
      while (topMoistureValue < moistureThreshold || bottomMoistureValue < moistureThreshold) {
        // Check water level before each iteration
        if (!checkWaterLevelAndAlarm()) {
          Serial.println("Watering process aborted due to low water level.");
          break;  // Break