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--- en:iot:examples:dhtoled [2021/03/05 12:06] – heiko.pikner
+++ en:iot:examples:dhtoled [Unknown date] (current) – external edit (Unknown date) 127.0.0.1
@@ Line 1: / Line 1: @@
+====== DHT and OLED example ======
+This example demonstrates how DHT senor can send temperature and humidity readings to the OLED screen with the ITT IoT framework.
+For this example you will need two controllers. One with the OLED shield and the other with the DHT sensor shield.
+{{:en:iot:examples:20200610_200205.jpg?300|DHT and OLED example}}
+Once the code has been uploaded the DHT controller will send temperature and humidity messages via MQTT to the OLED module.
+To upload the code you need to create two projects in PlatformIO environment.
+One for the controller with the OLED shield and the other for the DHT sensor shield.
+The following is the code for the controller with the DHT shield. Needed libaries:
+<code>lib_deps = ITTIoT, DHT sensor library, Adafruit Unified Sensor</code>
+<fc #ff0000>After programming, if NAN appears instead of readings, the USB cable should be disconnected and reconnected!</fc>
+<code c>
+// Includes global variables and librarys that the DHT uses
+#include <Arduino.h>
+#include <ittiot.h>
+#include <Ticker.h>
+#include <DHT.h>
+#define WIFI_NAME "name"
+#define WIFI_PASSWORD "password"
+#define DHTPIN D3     // Pin where DHT shield is connected. Change this to D4 if the shield has no legs removed.
+#define DHTTYPE DHT22   // DHT 22  (AM2302)
+// Create an object for DHT sensor
+DHT dht(DHTPIN, DHTTYPE);
+// Create an object for Ticker library
+Ticker timeTicker;
+bool sendDataFlag;
+// Ticker library callback, which will occur 0.5 second interval.
+void sendData()
+{
+  sendDataFlag=true;
+}
+// Function started after the connection to the server is established.
+void iot_connected()
+{
+  // Send message to serial port to show that connection is established
+  Serial.println("MQTT connected callback");
+  // Send message to MQTT server to show that connection is established
+  iot.log("IoT DHT example!");
+}
+void setup()
+{
+  // Initialize serial port and send message
+  Serial.begin(115200); // setting up serial connection parameter
+  Serial.println("Booting");
+  //iot.setConfig("wname", WIFI_NAME);
+  //iot.setConfig("wpass", WIFI_PASSWORD);
+  iot.printConfig(); // print IoT json config to serial
+  iot.setup(); // Initialize IoT library
+  // Initialize DHT library
+  dht.begin();
+  // Initialize Ticker interval and callback
+  timeTicker.attach(1, sendData);
+}
+void loop()
+{
+  iot.handle(); // IoT behind the plan work, it should be periodically called
+  if(sendDataFlag)
+  {
+    sendDataFlag = false;
+    // Read humidity and temperature
+    float h = dht.readHumidity();
+    float t = dht.readTemperature();
+    // Create a buffer to store strings to being sent later
+    char buf[10];
+    // Convert temperature value messages to strings and send to the MQTT server
+    String(t).toCharArray(buf,10);
+    iot.publishMsg("temp",buf);
+    // Convert humidity value messages to strings and send to the MQTT server
+    String(h).toCharArray(buf,10);
+    iot.publishMsg("hum",buf);
+  }
+}
+</code>
+The following is the code for the controller module with the OLED shield.
+<code>lib_deps = ITTIoT, Adafruit GFX Library, Adafruit SSD1306 Wemos Mini OLED, adafruit/Adafruit BusIO</code>
+<code c>
+// Includes global variables and librarys that the OLED display uses
+#include <Arduino.h>
+#include <ittiot.h>
+#include <Adafruit_I2CDevice.h>
+#include <Adafruit_GFX.h>
+#include <Adafruit_SSD1306.h>
+#define WIFI_NAME "name"
+#define WIFI_PASSWORD "password"
+// Change it according to the real name of the microcontroller where DHT shield is connected
+#define DHT_TOPIC "ESP30"
+// OLED reset pin is GPIO0
+#define OLED_RESET 0
+// Create an object for OLED screen
+Adafruit_SSD1306 display(OLED_RESET);
+// Define variables to store humidity and temperature values
+float h;
+float t;
+// Message received
+void iot_received(String topic, String msg)
+{
+  // Check if topic contains temperature data
+  if(topic == (DHT_TOPIC"/temp"))
+  {
+    t = msg.toFloat(); // Convert string to float
+  }
+  // Check if topic contains humidity data
+  if(topic == (DHT_TOPIC"/hum"))
+  {
+    h = msg.toFloat(); // Convert string to float
+  }
+}
+// Function started after the connection to the server is established.
+void iot_connected()
+{
+  // Send message to serial port to show that connection is established
+  Serial.println("MQTT connected callback");
+  // Subscribe to topics to get temperature and humidity messages
+  iot.subscribe(DHT_TOPIC"/temp");
+  iot.subscribe(DHT_TOPIC"/hum");
+  // Send message to MQTT server to show that connection is established
+  iot.log("IoT OLED example!");
+}
+void setup()
+{
+  // Initialize serial port and send message
+  Serial.begin(115200); // setting up serial connection parameter
+  Serial.println("Booting");
+  // Initialize OLED with the I2C addr 0x3C (for the 64x48)
+  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
+  // Display "booting..." message
+  display.clearDisplay();
+  display.setTextSize(1);
+  display.setTextColor(WHITE);
+  display.setCursor(0,0);
+  display.println("Booting...");
+  display.display();
+  //iot.setConfig("wname", WIFI_NAME);
+  //iot.setConfig("wpass", WIFI_PASSWORD);
+  iot.printConfig(); // print IoT json config to serial
+  iot.setup(); // Initialize IoT library
+}
+void loop()
+{
+  iot.handle();// IoT behind the plan work, it should be periodically called
+  // Display temperature and humidity readings to OLED screen
+  display.clearDisplay(); // cleanse the OLED display
+  display.setTextSize(1); // sets the text size
+  display.setTextColor(WHITE); // sets the text color
+  display.setCursor(0,0); // sets the cursor position
+  display.println("Temp: "); // writes text
+  display.println(t); // write temperature value
+  display.setCursor(0,20);
+  display.println("Hum: ");
+  display.println(h);
+  display.display();
+  delay(200); // Waiting 0.2 second
+}
+</code>