Connecting a DHT11 sensor to the cloud with an ESP8266-based board

main.cpp

#include <Arduino.h>
#include <ESP8266WiFi.h>
#include <Cloud4RPi.h>
#include "DHT.h"

#ifndef LED_BUILTIN
#define LED_BUILTIN 2
#endif

#define DHTPIN 2        // Digital pin connected to the DHT sensor
#define DHTTYPE DHT11   // DHT 11, DHT 22  (AM2302) AM2321, DHT 21 (AM2301)
#define SERIAL_BAUD_RATE 9600 // bits per second

// Decrease this value for testing purposes.
const int dataSendingInterval = 5 * 60 * 1000; // milliseconds
const int diagSendingInterval = 60 * 1000; // milliseconds

unsigned long lastDataSent = 0 - dataSendingInterval; // for reading first time in loop()
unsigned long lastDiagSent = 0 - diagSendingInterval;
unsigned long currentMillis;

struct DHT_Result {
    float h;
    float t;
};

void ensureWiFiConnection();
bool onLEDCommand(bool value);
void readSensors();
String uptimeHumanReadable(unsigned long milliseconds);

#if defined(CLOUD4RPI_TOKEN)
    Cloud4RPi c4r(CLOUD4RPI_TOKEN);
#else
    Cloud4RPi c4r("!!!_NO_DEVICE_TOKEN_!!!");
#endif

// Create DHT sensor
DHT dht(DHTPIN, DHTTYPE);
DHT_Result dhtResult;

WiFiClient wifiClient;

void setup() {
    Serial.begin(SERIAL_BAUD_RATE);
    ensureWiFiConnection();

    pinMode(LED_BUILTIN, OUTPUT);
    digitalWrite(LED_BUILTIN, HIGH);
    
    c4r.begin(wifiClient);
    c4r.printLogo();
    c4r.ensureConnection(); //TODO
    
    delay(1000);

    c4r.declareNumericVariable("DHT11_Temp");
    c4r.declareNumericVariable("DHT11_Hum");
    c4r.declareBoolVariable("LED_On", onLEDCommand);

    c4r.publishConfig();

    c4r.declareDiagVariable("IP_Address");
    c4r.declareDiagVariable("RSSI"); // WiFi signal strength
    c4r.declareDiagVariable("Uptime");

    dht.begin();

    c4r.loop();
    delay(1000);
}

void loop() {
    ensureWiFiConnection();

    if (c4r.ensureConnection(3)) { // number of attempts
        currentMillis = millis();

        if (currentMillis - lastDataSent >= dataSendingInterval) {
            Serial.println();

            readSensors();
            c4r.setVariable("DHT11_Temp", dhtResult.t);
            c4r.setVariable("DHT11_Hum", dhtResult.h);

            c4r.publishData();
            lastDataSent = currentMillis;

            Serial.print(F("Variables state:"));
            Serial.print(F("  Humidity: "));
            Serial.println(dhtResult.h);
            Serial.print(F("  Temperature: "));
            Serial.print(dhtResult.t);
            Serial.println(F("°C "));
            Serial.print("  LED = ");
            Serial.println(c4r.getBoolValue("LED_On") ? "On" : "Off");
        }

        if (currentMillis - lastDiagSent >= diagSendingInterval) {
            c4r.setDiagVariable("RSSI", (String)WiFi.RSSI() + " dBm");
            c4r.setDiagVariable("IP_Address", WiFi.localIP().toString());
            c4r.setDiagVariable("Uptime", uptimeHumanReadable(currentMillis));
            
            c4r.publishDiag();
            lastDiagSent = currentMillis;
        }
    }
    c4r.loop();
    Serial.print(".");
    delay(1000);
}

void ensureWiFiConnection() {
    if (WiFi.status() != WL_CONNECTED) {
        #if defined(SSID_NAME) && defined(SSID_PASWORD)
                WiFi.begin(SSID_NAME, SSID_PASSWORD);
        #endif

        while (WiFi.status() != WL_CONNECTED) {
            Serial.println("Connecting to Wi-Fi...");
            delay(2000);
        }
        Serial.print("Connected! IP: ");
        Serial.println(WiFi.localIP());
    }
}

void readSensors() {
    float h = dht.readHumidity();
    // Read temperature as Celsius (the default)
    float t = dht.readTemperature();

    // Check if any reads failed and exit
    if (isnan(h) || isnan(t)) {
        Serial.println(F("Failed to read from DHT sensor!"));
        return;
    }
    dhtResult.h = h;
    dhtResult.t = t;
}

bool onLEDCommand(bool value) {
    Serial.print("LED state set to ");
    Serial.println(value);
    digitalWrite(LED_BUILTIN, value ? LOW: HIGH);
    return !digitalRead(LED_BUILTIN);
}

String uptimeHumanReadable(unsigned long milliseconds) {
    static char uptimeStr[32];
    unsigned long secs = milliseconds / 1000;
    unsigned long mins = secs / 60;
    unsigned int hours = mins / 60;
    unsigned int days = hours / 24;
    secs -= mins * 60;
    mins -= hours * 60;
    hours -= days * 24;
    sprintf(uptimeStr,"%d day(s) %2.2d:%2.2d:%2.2d", (byte)days, (byte)hours, (byte)mins, (byte)secs);
    return String(uptimeStr);
}

platformio.ini

[platformio]
default_envs = nodemcuv2

[env:nodemcuv2]
platform = espressif8266
framework = arduino
board = nodemcuv2

; Library options
lib_deps =
    cloud4rpi-esp-arduino
    Adafruit Unified Sensor
    DHT sensor library

build_flags =
    -D MQTT_MAX_PACKET_SIZE=1024
    -D MQTT_MAX_TRANSFER_SIZE=128
    -D CLOUD4RPI_DEBUG=0
    -D SSID_NAME=\"__YOUR_WIFI__\"
    -D SSID_PASSWORD=\"__YOUR_WIFI_PASS__\"
    -D CLOUD4RPI_TOKEN=\"__YOUR_DEVICE_TOKEN__\"