💻 Complete Solar IoT Sensor Code - Battery-Powered Soil Monitoring

⚡ How Solar IoT Works

📖 Complete Solar Sensor Code

#include <WiFi.h>
#include <HTTPClient.h>

const char* ssid = "YOUR_WIFI";
const char* password = "YOUR_PASSWORD";
const char* token = "YOUR_TOKEN";

#define SOIL_PIN 32
#define BATTERY_PIN 34

const int DRY = 3800, WET = 1500;
RTC_DATA_ATTR int bootCount = 0;
RTC_DATA_ATTR int lastMoisture = 0;

// ========== READ SENSORS ==========
int readSoil() {
    int m = map(analogRead(SOIL_PIN), DRY, WET, 0, 100);
    return constrain(m, 0, 100);
}

float readBattery() {
    int raw = analogRead(BATTERY_PIN);
    return (raw / 4095.0) * 3.3 * 2;  // Voltage divider: 2x
}

// ========== SEND TO CLOUD ==========
void sendData(int moisture, float battery) {
    WiFi.begin(ssid, password);
    int tries = 0;
    while (WiFi.status() != WL_CONNECTED && tries < 20) {
        delay(200);
        tries++;
    }
    
    if (WiFi.status() == WL_CONNECTED) {
        HTTPClient http;
        http.begin("https://api.oceanremote.net/device/state");
        http.addHeader("Content-Type", "application/x-www-form-urlencoded");
        
        String data = "token=" + String(token);
        data += "&soil=" + String(moisture);
        data += "&battery=" + String(battery);
        http.POST(data);
        http.end();
        
        WiFi.disconnect(true);
        WiFi.mode(WIFI_OFF);
    }
}

// ========== SMART SLEEP ==========
int getSleepMinutes(int moisture, float battery) {
    if (battery < 3.3) return 60;      // Low battery → sleep longer
    if (moisture < 30)  return 5;       // Very dry → check often
    if (moisture > 70)  return 30;      // Very wet → check less
    return 15;                          // Normal → 15 min
}

// ========== SETUP ==========
void setup() {
    Serial.begin(115200);
    bootCount++;
    
    int m = readSoil();
    float v = readBattery();
    
    Serial.printf("Wake #%d | Soil: %d%% | Battery: %.2fV\n", bootCount, m, v);
    
    // Send only if changed or every 10th reading
    if (abs(m - lastMoisture) > 5 || bootCount % 10 == 0) {
        sendData(m, v);
        lastMoisture = m;
    }
    
    int sleep = getSleepMinutes(m, v);
    Serial.printf("💤 Sleep %d min\n", sleep);
    
    esp_sleep_enable_timer_wakeup(sleep * 60 * 1000000ULL);
    esp_deep_sleep_start();
}

void loop() {}
    

🔋 Key Power-Saving Techniques

• 😴 Deep sleep (2.5μA): ESP32 consumes almost nothing between readings
• 📡 Disable WiFi after sending: WiFi.disconnect(true); WiFi.mode(WIFI_OFF);
• 📦 Batch data: Send only when moisture changes significantly (>5%)
• ⏱️ Send less often: Wet soil? Sleep 30 min. Dry soil? Sleep 5 min.
• 🔋 Use RTC memory: RTC_DATA_ATTR preserves variables across deep sleep