# Controlling Relays and LEDs Through Get 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 Post Data using **POSTMAN** software which contains commands to control the LEDs and relays. Then the **Lynx-32 Development Board** performs **Get Data** from 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. {% 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. Antares ESP HTTP Library. This documentation uses the **Antares ESP HTTP library version 1.4.0.** {% hint style="info" %} If you have not installed **Antares ESP HTTP 1.4.0**, please follow these steps. [antares-wi-fi-http](https://docs.antares.id/en/getting-started/arduino-library-installation/antares-wi-fi-http "mention") {% endhint %} 3. Postman Software {% hint style="info" %} If you have not installed **POSTMAN Software**, you can follow the steps in the following link. [postman-installation](https://docs.antares.id/en/getting-started/software-installation/postman-installation "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 HTTP > Lynx32-Simple-Project > GET\_DATA\_RELAY\_LED.** {% endhint %} Here is the sample programme code of **GET\_DATA\_RELAY\_LED**. ```arduino #include // Include the AntaresESP32HTTP library #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 AntaresESPHTTP antares(ACCESSKEY); // Initialize AntaresESP32HTTP with the access key #define relayPin 25 // Digital pin for controlling the relay #define ledPin 12 // Digital pin for controlling the LED const unsigned long interval = 10000; // 10 seconds interval to send message unsigned long previousMillis = 0; // Will store the last time a message was sent void setup() { Serial.begin(115200); // Initialize serial communication antares.setDebug(true); // Enable Antares library debug mode antares.wifiConnection(WIFISSID, PASSWORD); // Connect to WiFi using provided SSID and password pinMode(relayPin, OUTPUT); // Set relay pin as output pinMode(ledPin, OUTPUT); // Set LED pin as output } void loop() { if (millis() - previousMillis > interval) { // Check if it's time to send a message previousMillis = millis(); // Update the last sent time antares.get(projectName, deviceName); // Get data from Antares if (antares.getSuccess()) { // Check if data retrieval was successful String dataValue = antares.getString("Relay"); // Get the value of "Relay" data field String ledValue = antares.getString("LED"); // Get the value of "LED" data field // Control relay based on received data if (dataValue == "1") { digitalWrite(relayPin, HIGH); // Turn on the relay } else if (dataValue == "0") { digitalWrite(relayPin, LOW); // Turn off the relay } // Control LED based on received data if (ledValue == "1") { digitalWrite(ledPin, HIGH); // Turn on the LED } else if (ledValue == "0") { digitalWrite(ledPin, LOW); // Turn off the LED } Serial.println("Received data - Relay: " + dataValue + " | LED: " + ledValue); } } } ``` ### 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. ```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 name of the **Wifi / Hotspot** that is currently being used by you. for example in the image below. {% endhint %}

WIFISSID

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

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. {% 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 %}

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

{% hint style="info" %} **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. {% endhint %} If the programme upload is successful, it will look like the following image..

Arduino IDE page image after successful upload.

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

{% 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. Setup POSTMAN Software In this step you need POSTMAN software, you can input the **end-point, request header** and **request** body first by following the following format. **End Point**
MethodPOST
URLhttps://platform.antares.id:8443/~/antares-cse/antares-id/your-application-name/your-device-name
{% hint style="info" %} Customise your-application-name and your-device-name to the names registered to your Antares account. {% endhint %} **Request Header**
KeyValue
X-M2M-Originyour-access-key
Content-Typeapplication/json;ty=4
Acceptapplication/json
{% hint style="info" %} Customise your-access-key with your Antares account access key. {% endhint %} The result will be as shown below.

Image of end-point and header settings in POSTMAN software

Next, you need to input the request body by following the following format. **Request Body** ```json { "m2m:cin": { "con": "{\"key1\":\"integer-value\", \"key2\":\"string-value\", \"keyN\":\"valueN\"}" } } ``` In the POSTMAN software, select the **Body** tab then select **raw** and enter the payload according to the request body you want to use as shown below.

Image of the contents of the payload reque

{% hint style="info" %} Customise the contents of the "con" field according to the "key" and "value" you want to send. {% endhint %} ### 6. Sending POSTMAN Messages to the Antares Server After the POSTMAN software setup is complete, it's time to send the POST command. The "Relay" field is filled with the string "1" for **RELAY ON** or "0" for **RELAY OFF**. The "LED" field is filled with the string "1" for **LED ON** or "0" for **LED OFF**. The "Relay" and "LED" fields are command messages to control the Relay and LED that will be sent via HTTP protocol to the Antares server. ```json { "m2m:cin": { "con": "{\"Relay\":\"1\", \"LED\":\"1\"}" } } ``` {% hint style="info" %} Customise the contents of the "Relay" and "LED" fields according to the get command you want to send. Give the value "1" or "0" to switch on or off. {% endhint %} If you have finished filling in the "test" field, then press the **Send** button on the POSTMAN software. The HTTP request indicator through the POSTMAN software is successful, the POSTMAN software response section will appear as shown below

Image of API hit response in POSTMAN software.

### 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.
{% hint style="info" %} The data received by **Lynx-32** with HTTP protocol is in the form of Relay variables and LEDs. {% endhint %} ### 8. Output Program Get data from the **Antares IoT Platform** and drive the relay and switch on the LED.

Relay and LED ON Result