| Status | ||||||
|---|---|---|---|---|---|---|
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- OpenDevice server up and running (guide)
- Arduino IDE (with required OpenDevice Libraries)
- ESP8266 module (like NodeMCU)
- DHT22/DHT11 sensor (and Adafruit's DHT22 library)
DHT22 |
NodeMCU |
|---|
Wiring
The most basic DHT humidity and temperature sensor comes in two variants with different levels of accuracy.
| DHT-11 | DHT-22 | |
|---|---|---|
| Humidity range | 20%-80%RH (±5%RH) | 0%-100%RH (±2%RH) |
| Temperature range | 0-50°C (±2°C) | -40-80°C (±0.5°C) |
| Measurement time | 1s per sample | 2s per sample |
Setup
To program the NodeMCU, we are going to use Arduino's IDE. It's the easiest way to get up and running with the DHT22.
First, you'll have to set up your machine (Device Setup Instructions). These instructions take you through installing the IDE, ESP8266 and the required libraries.
In addition to this, you'll have to install DHT sensor library to read the sensor, we are going to use Adafruit's DHT22 library, and Adafruit Unified Sensor Driver
Install Adafruit's DHT22 library using Library Manager:
Next, install Adafruit Unified Sensor Driver
Code / Firmware
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Basically when importing the libraries below, we are activating the WiFi communication and the MQTT protocol.
| Code Block | ||
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#include <ESP8266WiFi.h> // Enable ESP8266 / WiFi #include <PubSubClient.h> // enable MQTT #include <ArduinoOTA.h> // Remote Updates // Sensor Libraries #include <Adafruit_Sensor.h> #include <DHT.h> #include <DHT_U.h> #include <OpenDevice.h> // Must be included after |
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App Code (full example)
| Code Block | ||
|---|---|---|
| ||
#define DHTPIN D2 // Pin which is connected to the DHT sensor.
// Available types: DHT11, DHT22, DHT21
DHT_Unified dht(DHTPIN, DHT11);
DHT_Unified::Temperature sTemp = dht.temperature();
DHT_Unified::Humidity sHumidity = dht.humidity();
void setup() {
Serial.begin(115200);
ODev.name("ODevHT-01");
ODev.apiKey("----APIKEY-----");
ODev.server("----SERVER IP-----");
dht.begin(); // Initialize device.
ODev.addSensor("HT01_Temperature", new AdafruitSensor(sTemp))
->setInterval(1 * (1000)); // 1sec
ODev.addSensor("HT01_Humidity", new AdafruitSensor(sHumidity))
->setInterval(1 * (1000)); // 1sec
WiFi.mode(WIFI_AP_STA);
WiFi.begin("---- WIFI----", "---- PASS----");
ODev.begin();
}
void loop() {
ODev.loop();
} |
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