Controlling Relays and LEDs Through Retrieve Commands

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 publish data using MQTTX which contains commands to control the LEDs and relays. Then the Lynx-32 Development Board subscribes data to the Antares IoT Platform which contains two command options, namely if the Relay input is 1 then the relay will turn on; Relay input is 0 then the relay will turn off; LED is 1 then the LED will turn on; LED input is 0 then the LED will turn off.

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.

The additional materials specific to this project are as follows.

1. Shield Workshop Antares

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

1. MQTTX Software

Follow These Steps

1. Launch the Arduino IDE application

2. Opening Sample Programme

Here is the sample programme code of RETRIEVE_DATA_RELAY_LED.

// Include necessary libraries
#include <AntaresESPMQTT.h> // Include the ESP32 HTTP library
#include <Adafruit_SSD1306.h> // Include the OLED library

// Replace these with your own credentials
#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

#define relayPin 25
#define ledPin 12

const unsigned long interval = 10000;    // 10 s interval to send message
unsigned long previousMillis = 0;  // will store last time message sent

AntaresESPMQTT antares(ACCESSKEY);

void callback(char topic[], byte payload[], unsigned int length) {
  antares.get(topic, payload, length);

  Serial.println("New Message!");
  Serial.println("Topic: " + antares.getTopic());
  Serial.println("Payload: " + antares.getPayload());

  String relayValue = antares.getString("Relay"); // Change data field to "Relay"
  String ledValue = antares.getString("LED");     // Add reading for "LED" data field
  // Control relay based on received data
  if (relayValue == "1") {
  digitalWrite(relayPin, HIGH);
  } 
  else if (relayValue == "0") {
  digitalWrite(relayPin, LOW);
  }

  // Control LED based on received data
  if (ledValue == "1") {
  digitalWrite(ledPin, HIGH);
  } 
  else if (ledValue == "0") {
  digitalWrite(ledPin, LOW);
  }

  Serial.println("Received data - Relay: " + relayValue + " | LED: " + ledValue);
  
}

void setup() {
    Serial.begin(115200); // Initialize serial communication
    antares.setDebug(true); // Enable debugging for Antares
    antares.wifiConnection(WIFISSID, PASSWORD); // Connect to WiFi
    antares.setMqttServer();
    antares.setCallback(callback);
    pinMode(relayPin, OUTPUT); // Set relayPin as an output
    pinMode(ledPin, OUTPUT); // Set ledPin as an output
}

void loop() {
 /*
    Check if we're still connected to the MQTT broker/server.
    If disconnected, the device will try to reconnect.
   */
  antares.checkMqttConnection();
}

3. Set WiFi Credential and Antares Credential in Program 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

4. Compile and Upload Program

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

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.

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

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.

5. MQTTX Software Setup

Open the MQTTX App, then select New Connection

In order to configure MQTTX with Antares broker, adjust the Name, Host and Port as shown below, then click Connect.

If it is connected, there is a notification as shown belowt

Enter Topic and Payload in the fields in MQTTX.

{
      "m2m:rqp": {
        "fr": "your-access-key",
        "to": "/antares-cse/antares-id/nama-aplikasi-anda/nama-device-anda",
        "op": 1,
        "rqi": 123456,
        "pc": {
          "m2m:cin": {
            "cnf": "message",
            "con": "{\"your-first-data\":\"the-integer-value\",\"your-second-data\":\"the-string-data\"}"
          }
        },
        "ty": 4
      }
    }

In the MQTTX software, enter the Topic and Payload that you want to use. Then click Publish to send the message from MQTTX to the Antares server.

6. Sending MQTTX Messages to the Antares Server

After the MQTTX software setup is complete, it's time to send the PUBLISH command. The "Relay" field is filled with the string "1" or "0" as the command message for the Relay which will be sent via the MQTT protocol to the Antares server. The "LED" field is filled with the string "1" for LED ON or "0" for LED OFF as a command message for the LED that will be sent via the MQTT protocol to the Antares server.

{
      "m2m:rqp": {
        "fr": "your-access-key",
        "to": "/antares-cse/antares-id/nama-aplikasi-anda/nama-device-anda",
        "op": 1,
        "rqi": 123456,
        "pc": {
          "m2m:cin": {
            "cnf": "message",
            "con": "{\"Relay\":\"1\",\"LED\":\"1\"}"
          }
        },
        "ty": 4
      }
    }

If you have finished filling in the "test" field, then press the PUBLISH button on the MQTTX software located to the right of the Topic filling column, as shown below.

If it has been published, the MQTTX page will have a message like the following.

7. Check Data in Antares

After uploading the programme successfully, then open the device antares page and see if the data has been successfully sent.

8. View Retrieve Message

Retrieve data from the Antares IoT Platform and display it on the OLED display after connecting to Wi-Fi as shown in the figure below: