Sensor Monitoring

This example demonstrates how to read sensor data and send it to your DecentIoT dashboard using Firebase real-time synchronization. We'll use a DHT22 temperature and humidity sensor.

Hardware Required

ESP8266 or ESP32 development board
DHT22 temperature and humidity sensor
10kΩ pull-up resistor
Breadboard and jumper wires

Wiring

ESP8266/ESP32    DHT22
GPIO 4 (D2)  →   Data Pin
3.3V         →   VCC
GND          →   GND
GPIO 4 (D2)  →   10kΩ Resistor → 3.3V (pull-up)

Code

/*
  DecentIoT Firebase Library - Simple DHT Sensor Example
  
  Hardware:
  - DHT22 sensor on pin D4
  - LED on pin D6
  
  Virtual Pins:
  - P0: LED Control (receive)
  - P1: Temperature (send)
  - P2: Humidity (send)
*/

#include <DecentIoT.h>
#include <ESP8266WiFi.h>
#include <DHT.h>

// Firebase credentials
#define FIREBASE_URL "your-firebase-url"
#define FIREBASE_AUTH "your-web-api-key"
#define AUTH_EMAIL "your-auth-email"
#define AUTH_PASS "your-auth-password"
#define PROJECT_ID "your-project-id"
#define USER_ID "your-user-id"
#define DEVICE_ID "your-device-id"
#define WIFI_SSID "your-wifi-name"
#define WIFI_PASS "wifi-password"

// Hardware pins
#define LED_PIN D6
#define DHT_PIN D4

// Create DHT sensor
DHT dht(DHT_PIN, DHT22);

// LED control from dashboard
DECENTIOT_RECEIVE(P0) {
    digitalWrite(LED_PIN, value);
    Serial.printf("[P0]LED: %s\n", value ? "ON" : "OFF");
}

// Send temperature every 10 seconds
DECENTIOT_SEND(P1, 10000) {
    float temp = dht.readTemperature();
    DecentIoT.write(P1, temp);
    Serial.printf("[P1] Temperature: %.1f°C\n", temp);
}

// Send humidity every 10 seconds
DECENTIOT_SEND(P2, 10000) {
    float humidity = dht.readHumidity();
    DecentIoT.write(P2, humidity);
    Serial.printf("[P2] Humidity: %.1f%%\n", humidity);
}

void setup() {
    Serial.begin(115200);
    
    // Initialize pins
    pinMode(LED_PIN, OUTPUT);
    pinMode(LED_BUILTIN, OUTPUT);
    digitalWrite(LED_PIN, LOW);
    
    // Initialize DHT sensor
    dht.begin();
    
    // Connect to WiFi
    WiFi.begin(WIFI_SSID, WIFI_PASS);
    while (WiFi.status() != WL_CONNECTED) {
        delay(500);
        Serial.print(".");
    }
    Serial.println("[WiFi] connected!");
    
    // Initialize DecentIoT
    DecentIoT.begin(FIREBASE_URL, FIREBASE_AUTH, PROJECT_ID, USER_ID, DEVICE_ID, AUTH_EMAIL, AUTH_PASS);
}

void loop() {
    DecentIoT.run();
    delay(10);
}

Dashboard Setup

Create Project in DecentIoT web dashboard
Add Firebase project credentials
Create device and datastreams
Add Widgets:
- P0: Button/Switch for LED control
- P1: Gauge for temperature
- P2: Gauge for humidity
Save and monitor the data

How It Works

Scheduled Tasks: DECENTIOT_SEND macros create recurring tasks
Sensor Reading: DHT22 sensor provides temperature and humidity
Virtual Pins: P0 for LED control, P1 for temperature, P2 for humidity
Real-time Sync: Firebase automatically syncs data to dashboard
Automatic Processing: Library handles all communication seamlessly

Firebase Real-time Features

Automatic Synchronization

Firebase provides real-time synchronization, so your dashboard automatically updates when new data arrives:

// Data is automatically synced to dashboard
DecentIoT.write("P1", temperature);
// Dashboard updates immediately without additional code

Automatic Processing

The library automatically handles all communication:

DECENTIOT_SEND(P1, 10000) {
  float temperature = dht.readTemperature();
  if (!isnan(temperature)) {
    DecentIoT.write("P1", temperature);
    // Library automatically processes all communication
  }
}

Advanced Features

Error Handling

// Enhanced sensor reading with error handling
DECENTIOT_SEND(P1, 10000) {
  float temperature = dht.readTemperature();
  if (!isnan(temperature)) {
    DecentIoT.write("P1", temperature);
    Serial.printf("[P1] Temperature: %.1f°C\n", temperature);
  } else {
    // Send error status
    DecentIoT.write("P1", -999);
    Serial.println("[P1] Sensor error - check connections");
  }
}

Multiple Sensors

// Add more sensors to different virtual pins
DECENTIOT_SEND(P3, 5000) {
  int lightLevel = analogRead(A0);
  DecentIoT.write("P3", lightLevel);
  Serial.printf("[P3] Light Level: %d\n", lightLevel);
}

DECENTIOT_SEND(P4, 15000) {
  float pressure = readPressure(); // Your pressure sensor function
  DecentIoT.write("P4", pressure);
  Serial.printf("[P4] Pressure: %.2f hPa\n", pressure);
}

Custom Intervals

// Different reading intervals for different sensors
DECENTIOT_SEND(P1, 5000) {   // Temperature every 5 seconds
  float temp = dht.readTemperature();
  DecentIoT.write("P1", temp);
}

DECENTIOT_SEND(P2, 30000) {  // Humidity every 30 seconds
  float humidity = dht.readHumidity();
  DecentIoT.write("P2", humidity);
}

Troubleshooting

Sensor not reading:

Check wiring connections
Verify DHT22 pin assignment
Check pull-up resistor (10kΩ)
Wait 2 seconds after power-on for sensor initialization

Invalid readings:

Check power supply (3.3V)
Verify sensor is DHT22 (not DHT11)
Check for loose connections

No data on dashboard:

Verify virtual pin mapping (P1, P2)
Check Firebase connection status
Ensure dashboard widgets are configured correctly
Check Firebase database rules

Instructions not received:

Ensure DecentIoT.run() is called regularly in your main loop
Check Firebase authentication
Verify database rules allow read/write access

Required Libraries

Install these libraries via Arduino Library Manager:

DHT sensor library by Adafruit
Adafruit Unified Sensor (dependency)

Next Steps

Advanced Control Example - Multiple sensors and actuators
MQTT Examples - Alternative to Firebase
Scheduling Guide - Advanced scheduling features

Sensor Monitoring

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