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ESP32C3 Smart Irrigation System with OLED Display and Soil Moisture Sensor

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Circuit Documentation

Summary

This circuit is designed to automate the watering of plants using a capacitive soil moisture sensor, an ESP32C3 microcontroller, and a 5V mini water pump. The system reads the soil moisture level and activates the water pump when the moisture level falls below a predefined threshold. The circuit also includes an OLED display for real-time monitoring and pushbuttons for user interaction.

Component List

  1. ESP32C3 Supermini

    • Description: A microcontroller with Wi-Fi and Bluetooth capabilities.
    • Pins: GPIO05, GPIO06, GPIO07, GPIO08, GPIO09, GPIO10, GPIO20, GPIO21, GPIO00, GPIO01, GPIO02, GPIO03, GPIO04, 3.3V, GND, +5V

  2. 0.96" OLED

    • Description: A small OLED display for visual output.
    • Pins: GND, VDD, SCK, SDA

  3. DFRobot Capacitive Soil Moisture Sensor (V1.0)

    • Description: A sensor to measure soil moisture levels.
    • Pins: A, VCC, GND

  4. Pushbutton (4 units)

    • Description: Buttons for user input.
    • Pins: Pin 3 (out), Pin 4 (out), Pin 1 (in), Pin 2 (in)

  5. 5V Mini Water Pump

    • Description: A small water pump for irrigation.
    • Pins: positive pin, negative pin

  6. 5V Battery

    • Description: Power source for the circuit.
    • Pins: +, -

Wiring Details

ESP32C3 Supermini

0.96" OLED

DFRobot Capacitive Soil Moisture Sensor (V1.0)

Pushbuttons

5V Mini Water Pump

5V Battery

Code Documentation

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <EEPROM.h>
#include <AT24C256.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define AT24C256_ADDRESS 0x50
AT24C256 eeprom(AT24C256_ADDRESS);

// EEPROM Address Constants
#define EEPROM_DRY_VALUE_ADDR 0
#define EEPROM_WET_VALUE_ADDR (EEPROM_DRY_VALUE_ADDR + sizeof(int))
#define EEPROM_LOW_THRESHOLD_ADDR (EEPROM_WET_VALUE_ADDR + sizeof(int))
#define EEPROM_HIGH_THRESHOLD_ADDR (EEPROM_LOW_THRESHOLD_ADDR + sizeof(int))
#define EEPROM_PUMP_DURATION_ADDR (EEPROM_HIGH_THRESHOLD_ADDR + sizeof(int))
#define EEPROM_WAIT_DURATION_ADDR (EEPROM_PUMP_DURATION_ADDR + sizeof(int))

// Pin definitions
#define SOIL_SENSOR_PIN A4     // ADC pin for soil moisture sensor
#define PUMP_PIN 10            // Pump control pin
#define MODE_BTN 0             // Mode button pin
#define SELECT_BTN 1           // Select button pin
#define UP_BTN 2               // Up button pin
#define DOWN_BTN 3             // Down button pin

// Screen states
enum Screen {
  MAIN_SCREEN,
  CALIBRATION,
  SET_THRESHOLD,
  SET_DURATION,
  MANUAL
};

enum CalibrationOption {
  DRY,
  WET
};

enum ThresholdOption {
  LOW_THRESHOLD,
  HIGH_THRESHOLD
};

enum DurationOption {
  PUMP_DURATION,
  WAIT_DURATION
};

// Variables
Screen currentScreen = MAIN_SCREEN;
CalibrationOption currentCalibrationOption = DRY;
ThresholdOption currentThresholdOption = LOW_THRESHOLD;
DurationOption currentDurationOption = PUMP_DURATION;
int moistureValue = 0;
int moisturePercent = 0;
int threshold_low = 30;
int threshold_high = 80;
int pumpDuration = 10000;    // 10 seconds in milliseconds
int waitDuration = 20000;    // 20 seconds in milliseconds
bool isPumping = false;
bool canPump = true;         
unsigned long pumpStartTime = 0;
unsigned long waitStartTime = 0;
unsigned long lastReadTime = 0;

// Calibration values
int dryValue = 3460;    
int wetValue = 1240;    

// Change tracking
bool calibrationChanged = false;
bool thresholdChanged = false;
bool durationChanged = false;

void saveToEEPROM() {
  EEPROM.put(EEPROM_DRY_VALUE_ADDR, dryValue);
  EEPROM.put(EEPROM_WET_VALUE_ADDR, wetValue);
  EEPROM.put(EEPROM_LOW_THRESHOLD_ADDR, threshold_low);
  EEPROM.put(EEPROM_HIGH_THRESHOLD_ADDR, threshold_high);
  EEPROM.put(EEPROM_PUMP_DURATION_ADDR, pumpDuration);
  EEPROM.put(EEPROM_WAIT_DURATION_ADDR, waitDuration);
}

void loadFromEEPROM() {
  int storedDryValue, storedWetValue, storedLowThreshold, 
      storedHighThreshold, storedPumpDuration, storedWaitDuration;

  EEPROM.get(EEPROM_DRY_VALUE_ADDR, storedDryValue);
  EEPROM.get(EEPROM_WET_VALUE_ADDR, storedWetValue);
  EEPROM.get(EEPROM_LOW_THRESHOLD_ADDR, storedLowThreshold);
  EEPROM.get(EEPROM_HIGH_THRESHOLD_ADDR, storedHighThreshold);
  EEPROM.get(EEPROM_PUMP_DURATION_ADDR, storedPumpDuration);
  EEPROM.get(EEPROM_WAIT_DURATION_ADDR, storedWaitDuration);

  // Validate stored values to prevent using uninitialized EEPROM
  if (storedDryValue > 0 && storedDryValue < 4096) dryValue = storedDryValue;
  if (storedWetValue > 0 && storedWetValue < 4096) wetValue = storedWetValue;
  if (storedLowThreshold >= 0 && storedLowThreshold <= 100) threshold_low = storedLowThreshold;
  if (storedHighThreshold >= 0 && storedHighThreshold <= 100) threshold_high = storedHighThreshold;
  if (storedPumpDuration > 0 && storedPumpDuration < 60000) pumpDuration = storedPumpDuration;
  if (storedWaitDuration > 0 && storedWaitDuration < 120000) waitDuration = storedWaitDuration;
}

void setup() {
  Serial.begin(115200);

  // Load saved settings
  loadFromEEPROM();

  // Initialize OLED
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }
  display.clearDisplay();

  // Initialize pins
  pinMode(PUMP_PIN, OUTPUT);
  pinMode(MODE_BTN, INPUT_PULLUP);
  pinMode(SELECT_BTN, INPUT_PULLUP);
  pinMode(UP_BTN, INPUT_PULLUP);
  pinMode(DOWN_BTN, INPUT_PULLUP);

  digitalWrite(PUMP_PIN, LOW);
}

int readSoilMoisture() {
  int sum = 0;
  // Take 5 readings for smoothing
  for (int i = 0; i < 5; i++) {
    sum += analogRead(SOIL_SENSOR_PIN);
    delay(10);
  }
  int avgReading = sum / 5;

  // Convert to