Retrieve Last Data from Antares Server with MQTT Protocol

In this project you will be directed to send simple data from the Lynx-32 Development Board to the Antares IoT Platform using WiFi connectivity with the MQTT protocol.

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.

General Prerequisites ESP32 Wi-Fi

The additional materials specific to this project are as follows.

1. Antares ESP HTTP Library. This documentation uses the Antares ESP MQTT library version 1.0.

If you have not installed Antares ESP MQTT version 1.0, you can follow these steps.

Antares Wi-Fi MQTT

Follow These Steps

1. Run the Arduino IDE application

2. Opening Sample Programme

You can open the programme code in the Arduino IDE via File > Examples > Antares ESP MQTT > AntaresMQTTRetrieveLatestData.

The following is the AntaresMQTTRetrieveLatestData example programme code

/*
    This is an example sketch to subscribe to MQTT data on ESP8266
    via the Antares IoT Platform.

    MQTT server & port:
    platform.antares.id, port 1338

    MQTT topic:
    /oneM2M/req/your-access-key/antares-cse/json

    The main function in this sketch is the callback function,
    which will be fired every time a new message is published
    to the topic.

    For more information, please visit https://antares.id/id/docs.html
*/

#include <AntaresESPMQTT.h>

#define ACCESSKEY "YOUR-ACCESS-KEY"       // Antares account access key
#define WIFISSID "YOUR-WIFI-SSID"         // Wi-Fi SSID to connect to
#define PASSWORD "YOUR-WIFI-PASSWORD"     // Wi-Fi password

#define projectName "YOUR-APPLICATION-NAME"   // Name of the application created in Antares
#define deviceName "YOUR-DEVICE-NAME"     // Name of the device created in Antares

AntaresESPMQTT antares(ACCESSKEY);

unsigned long previousMillis=0;
unsigned long interval =5000;

void callback(char topic[], byte payload[], unsigned int length) {
  /*
    Get the whole received data, including the topic,
    and parse the data according to the Antares data format.
  */
  antares.get(topic, payload, length);

  Serial.println("New Message!");
  // Print topic and payload
  Serial.println("Topic: " + antares.getTopic());
  Serial.println("Payload: " + antares.getPayload());
  // Print individual data
}

void setup() {
  Serial.begin(115200);
  antares.setDebug(true);
  antares.wifiConnection(WIFISSID, PASSWORD);
  antares.setMqttServer();
  antares.setCallback(callback);
}
void loop() {
  /*
    Check if we're still connected to the MQTT broker/server.
    If disconnected, the device will try to reconnect.
  */
  antares.checkMqttConnection();

  while(millis()-previousMillis > interval)
  {
    previousMillis = millis();
    antares.retrieveLastData(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.

#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

The *Access key parameter is obtained from your Antares account page.

Access Key Location on Antares Account Page

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.

WIFISSID

The *PASSWORD parameter is obtained from the WiFi password you are currently using.

The parameters *projectName and *deviceName are obtained from the Application Name and Device Name that have been created in the Antares account.

Application Name Display

Device Name Display

4. Compile and Upload Program

Connect the Lynx-32 with your computer and make sure the Communication Port is read.

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).

Device Manager Display

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

The Tick icon on the Arduino IDE is just the verify process. Usually used to Compile 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.

If the programme upload is successful, it will look like the following image.

Upload Successful Programme Output Display

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

Serial Monitor Icon

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

Serial Monitor Display

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.

5. Check Data in Antares

After uploading the programme successfully, then open the Antares device page and see if the data taken matches the data in the Antares Console.

Antares Console Display

The data sent from the Lynx-32 Development Board with the MQTT protocol is in the form of temperature, humidity, wind_speed, rain_level, and location variables containing latitude and longitude.