c_cpp esp8266.read.dht22.ino

Posted 2021-05-14

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

#define DHTPIN 2     // what pin we're connected to
#define DHTTYPE DHT22   // DHT 22  (AM2302)

#define DEBUG

#define DEBUG_PRINTER Serial

#ifdef DEBUG
#define DEBUG_PRINT(...) { DEBUG_PRINTER.print(__VA_ARGS__); }
#define DEBUG_PRINTLN(...) { DEBUG_PRINTER.println(__VA_ARGS__); }
#else
#define DEBUG_PRINT(...) {}
#define DEBUG_PRINTLN(...) {}
#endif

const char* ssid     = "OpenWrt_NAT_500GP.101";
const char* password = "activegateway";

DHT *dht;

void connectWifi();
void reconnectWifiIfLinkDown();
void initDht(DHT **dht, uint8_t pin, uint8_t dht_type);
void readDht(DHT *dht, float *temp, float *humid);

void setup() {
    Serial.begin(115200);
    delay(10);

    connectWifi();

    initDht(&dht, DHTPIN, DHTTYPE);
}

void loop() {
    static float t_ds;
    static float t_dht;
    static float h_dht;

    readDht(dht, &t_dht, &h_dht);
    DEBUG_PRINTLN(t_ds);
    // Wait a few seconds between measurements.
    delay(10 * 1000);

    reconnectWifiIfLinkDown();
}

void reconnectWifiIfLinkDown() {
    if (WiFi.status() != WL_CONNECTED) {
        DEBUG_PRINTLN("WIFI DISCONNECTED");
        connectWifi();
    }
}

void connectWifi() {
    DEBUG_PRINTLN();
    DEBUG_PRINTLN();
    DEBUG_PRINT("Connecting to ");
    DEBUG_PRINTLN(ssid);

    WiFi.begin(ssid, password);
    while (WiFi.status() != WL_CONNECTED) {
        delay(500);
        DEBUG_PRINT(".");
    }

    DEBUG_PRINTLN("");
    DEBUG_PRINTLN("WiFi connected");
    DEBUG_PRINTLN("IP address: ");
    DEBUG_PRINTLN(WiFi.localIP());
}

void initDht(DHT **dht, uint8_t pin, uint8_t dht_type) {
    // Connect pin 1 (on the left) of the sensor to +5V
    // NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1
    // to 3.3V instead of 5V!
    // Connect pin 2 of the sensor to whatever your DHTPIN is
    // Connect pin 4 (on the right) of the sensor to GROUND
    // Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor

    // Initialize DHT sensor for normal 16mhz Arduino
    // NOTE: For working with a faster chip, like an Arduino Due or Teensy, you
    // might need to increase the threshold for cycle counts considered a 1 or 0.
    // You can do this by passing a 3rd parameter for this threshold.  It's a bit
    // of fiddling to find the right value, but in general the faster the CPU the
    // higher the value.  The default for a 16mhz AVR is a value of 6.  For an
    // Arduino Due that runs at 84mhz a value of 30 works.
    // Example to initialize DHT sensor for Arduino Due:
    //DHT dht(DHTPIN, DHTTYPE, 30);

    *dht = new DHT(pin, dht_type, 30);
    (*dht)->begin();
    DEBUG_PRINTLN(F("DHTxx test!"))  ;
}

void readDht(DHT *dht, float *temp, float *humid) {

    if (dht == NULL) {
        DEBUG_PRINTLN(F("[dht22] is not initialised. please call initDht() first."));
        return;
    }

    // Reading temperature or humidity takes about 250 milliseconds!
    // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
    float h = dht->readHumidity();

    // Read temperature as Celsius
    float t = dht->readTemperature();
    // Read temperature as Fahrenheit
    float f = dht->readTemperature(true);

    // Check if any reads failed and exit early (to try again).
    if (isnan(h) || isnan(t) || isnan(f)) {
        DEBUG_PRINTLN("Failed to read from DHT sensor!");
        return;
    }

    // Compute heat index
    // Must send in temp in Fahrenheit!
    float hi = dht->computeHeatIndex(f, h);

    DEBUG_PRINT("Humidity: ");
    DEBUG_PRINT(h);
    DEBUG_PRINT(" %\t");
    DEBUG_PRINT("Temperature: ");
    DEBUG_PRINT(t);
    DEBUG_PRINT(" *C ");
    DEBUG_PRINT(f);
    DEBUG_PRINT(" *F\t");
    DEBUG_PRINT("Heat index: ");
    DEBUG_PRINT(hi);
    DEBUG_PRINTLN(" *F");

    *temp = t;
    *humid = f;

}


// the code is on this article: http://www.cmmakerclub.com/2015/06/1707