# Send DHT 11 Data and Display on OLED In this project, you will use the **Antares Workshop Shield** on the **Lynx-32 Development Board** module. In this **Antares Shield Workshop**, there are temperature, humidity (DHT11), relay, LED and push button sensors. You will monitor the temperature and humidity according to the specified interval period. The results of the data sent by the sensors can be monitored through the Antares console. ## Prerequisites The materials required follow the **General Prerequisites** on the previous page. If you have not prepared the requirements on that page, then you can visit the following page. {% content-ref url="../../general-prerequisites-esp32-wi-fi" %} [general-prerequisites-esp32-wi-fi](https://docs.antares.id/en/code-and-library-examples/esp32-wi-fi/general-prerequisites-esp32-wi-fi) {% endcontent-ref %} The additional materials specific to this project are as follows. 1. Shield Workshop Antares 2. I2C-based 0.96inch 128x64 pixel SSD1036 OLED module

3. Antares ESP HTTP Library. This documentation uses the **Antares ESP MQTT library version 1.0.** {% hint style="info" %} If you have not installed **Antares ESP MQTT version 1.0**, you can follow these steps. [antares-wi-fi-mqtt](https://docs.antares.id/en/getting-started/arduino-library-installation/antares-wi-fi-mqtt "mention") {% endhint %} 4. DHT11 Library. This documentation uses **DHT11 Sensor Library version 1.4.4.** {% hint style="info" %} If you have not installed the **DHT11 Sensor Library version 1.4.4**. you can follow the steps in the following link. [dht11-sensor-library](https://docs.antares.id/en/getting-started/arduino-library-installation/dht11-sensor-library "mention") {% endhint %} 5. SSD1306 OLED Library. This documentation uses **Adafruit SSD1306 by Adafruit version 2.5.7.** {% hint style="info" %} If you have not installed the **Adafruit SSD1306 by Adafruit library version 2.5.7.** you can follow the steps in the following link. [adafruit-ssd1306](https://docs.antares.id/en/getting-started/arduino-library-installation/adafruit-ssd1306 "mention") {% endhint %} ## Follow These Steps ### 1. Launch the Arduino IDE application ### 2. Opening Sample Programme {% hint style="info" %} You can open the programme code in the Arduino IDE via **File > Examples > Antares ESP MQTT > Lynx32-Simple-Project > SEND\_DATA\_DHT11\_OLED.** {% endhint %} The following is the sample programme code for **SEND\_DATA\_DHT11\_OLED.** ```arduino // Library initialization #include // Library initiation for Antares ESP32 MQTT #include "DHT.h" // Load DHT sensor library for reading temperature and humidity #include // Load OLED display library #define DHTPIN 14 // Define DHTPIN variable, pointing to pin 14 #define DHTTYPE DHT11 // Set DHT type to DHT11 #define SCREEN_WIDTH 128 // Define OLED screen width #define SCREEN_HEIGHT 64 // Define OLED screen height #define OLED_RESET -1 // Define OLED reset pin, set to -1 as it's not used #define SCREEN_ADDRESS 0x3C // Define OLED I2C address #define ACCESSKEY "YOUR-ACCESS-KEY" // Replace with your Antares account access key #define WIFISSID "YOUR-WIFI-SSID" // Replace with your Wi-Fi SSID #define PASSWORD "YOUR-WIFI-PASSWORD" // Replace with your Wi-Fi password #define projectName "YOUR-APPLICATION-NAME" // Replace with the Antares application name that was created #define deviceName "YOUR-DEVICE-NAME" // Replace with the Antares device name that was created const unsigned long interval = 10000; // 10 s interval to send message unsigned long previousMillis = 0; // will store last time message sent AntaresESPMQTT antares(ACCESSKEY); // Create an antares object for connecting to Antares DHT dht(DHTPIN, DHTTYPE); // Create a dht object for the DHT sensor Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET); // Create a display object for the OLED screen void setup() { Serial.begin(115200); // Initialize serial communication with baudrate 115200 antares.setDebug(true); // Turn on debug mode. Set to "false" if you don't want messages to appear in the serial monitor antares.wifiConnection(WIFISSID, PASSWORD); // Attempt to connect to Wi-Fi with the specified SSID and password antares.setMqttServer(); dht.begin(); // Initialize the DHT sensor object if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) { Serial.println(F("SSD1306 allocation failed")); // Check if the OLED is successfully initialized for (;;); } display.clearDisplay(); // Clear the OLED display display.setTextColor(SSD1306_WHITE); // Set text color to white display.setTextSize(1); // Set text size to 1 display.setCursor(0, 0); // Set cursor position to (0, 0) display.println(F("Temperature & Humidity")); // Display "Temperature & Humidity" text on the OLED display.display(); // Show the text on the OLED delay(2000); // Delay for 2 seconds } void loop() { antares.checkMqttConnection(); // Check interval overflow if (millis() - previousMillis > interval) { previousMillis = millis(); float hum = dht.readHumidity(); // Read humidity value from the DHT sensor float temp = dht.readTemperature(); // Read temperature value from the DHT sensor if (isnan(hum) || isnan(temp)) { // Check if the sensor reading is invalid Serial.println("Failed to read DHT sensor!"); // If the reading is invalid, print an error message return; // Exit the loop function and wait for the next cycle } display.clearDisplay(); // Clear the OLED display display.setTextSize(1); // Set text size to 1 display.setCursor(0, 0); // Set cursor position to (0, 0) display.print(F("Temperature: ")); // Display "Temperature: " text on the OLED display.print(temp); // Display temperature value on the OLED display.println(F(" C")); // Display " C" (for Celsius) on the OLED display.print(F("Humidity: ")); // Display "Humidity: " text on the OLED display.print(hum); // Display humidity value on the OLED display.println(F(" %")); // Display " %" (for percentage) on the OLED display.display(); // Show the text on the OLED Serial.println("Temperature: " + (String)temp + " *C"); // Print temperature value to the serial monitor with "*C" format Serial.println("Humidity: " + (String)hum + " %"); // Print humidity value to the serial monitor with "%" format // Add variable data to the storage buffer in Antares antares.add("temperature", temp); antares.add("humidity", hum); // Send data from the storage buffer to Antares antares.publish(projectName, deviceName); } } ``` ### 3. Set MQTT Parameters in Programme Code Change the HTTP Protocol parameters in the following variables **\*ACCESSKEY, \*WIFISSID, \*PASSWORD, \*projectName**, and **\*deviceName**. Adjust to the parameters in the Antares console. ```arduino #define ACCESSKEY "YOUR-ACCESS-KEY" // Replace with your Antares account access key #define WIFISSID "YOUR-WIFI-SSID" // Replace with your Wi-Fi SSID #define PASSWORD "YOUR-WIFI-PASSWORD" // Replace with your Wi-Fi password #define projectName "YOUR-APPLICATION-NAME" // Replace with the Antares application name that was created #define deviceName "YOUR-DEVICE-NAME" // Replace with the Antares device name that was created ``` {% hint style="info" %} The **\*Access key** parameter is obtained from your Antares account page. {% endhint %}

Access Key Location on Antares Account Page

{% hint style="info" %} The **WIFISSID** parameter is obtained from the **Wi-Fi/Hotspot** name that will be used by the **Lynx-32 Development Board**. An example is shown below. {% endhint %}

{% hint style="info" %} The **\*PASSWORD** parameter is obtained from the **Wi-Fi password** you are currently using. {% endhint %} {% hint style="info" %} The parameters **\*projectName** and **\*deviceName** are obtained from the **Application Name** and **Device Name** that have been created in the Antares account. {% endhint %}

### 4. Compile and Upload Program Connect the **Lynx-32** with your computer and make sure the **Communication Port** is read. {% hint style="info" %} On Windows operating systems the check can be done via **Device Manager**. If your **Lynx-32** is read then the **USB-Serial CH340** appears with the port adjusting the port availability (in this case it reads **COM4**). {% endhint %}

Set up the **ESP32** board by clicking **Tools > Board > esp32** in the Arduino IDE, then make sure the **ESP32 Dev Module** is used. Select the port according to the communication port that is read (in this case COM4). The result will look like the following image.

Display of Board Specifications and Ports Used

After all the setup is complete, upload the programme by pressing the arrow icon as shown below. Wait for the compile and upload process to finish

Compile Icon for Tick and Upload Icon for Arrow

{% hint style="info" %} **The Tick icon** on the Arduino IDE is just the verify process. Usually used to C**ompile** the programme to find out whether there are errors or not. \ **The Arrow icon** on the Arduino IDE is the verify and upload process. Usually used to **Compile** the programme as well as Flash the programme to the target board. {% endhint %} If the programme upload is successful, it will look like the following image.

After uploading the programme, you can view the **serial monitor** to debug the programme. The **serial monitor** icon is shown in the following image.

Set the **serial baud rate** to 115200 and select BothNL & CR. The result will look like the following image.

{% hint style="danger" %} Make sure the **serial baud rate** matches the value defined in the programme code. If the **serial baud rate** is not the same between **the programme code** and **the serial monitor**, the ASCII characters will not be read properly. {% endhint %} ### 5. Check Data in Antares After uploading the programme successfully, then open the device antares page and see if the data has been successfully sent.

{% hint style="info" %} Data sent from the **Lynx-32 Development Board** with the HTTP protocol in the form of temperature and humidity variables. {% endhint %} Here's the data that OLED displays.