Using NodeMCU as a Client & Server Application

The NodeMCU is a popular development board that makes it easy to connect to Wi-Fi and create IoT applications. In this guide, we’ll walk through the steps to set up your NodeMCU as both a server and a client using the Arduino IDE.

Prerequisites:

- NodeMCU board

- USB cable

- Arduino IDE installed

- Wi-Fi network

Step 1: Set Up the Arduino IDE

1. Install the NodeMCU Board Package:

- Open the Arduino IDE.

- Go to `File` -> `Preferences`.

- In the “Additional Board Manager URLs” field, add: `http://arduino.esp8266.com/stable/package_esp8266com_index.json`.

- Go to `Tools` -> `Board` -> `Boards Manager`.

- Search for `esp8266` and install the latest version.

2. Select the NodeMCU Board:

- Go to `Tools` -> `Board` and select `NodeMCU 1.0 (ESP-12E Module)`.

Step 2: Set Up NodeMCU as a Server

1. Open the Example Sketch:

- Go to `File` -> `Examples` -> `ESP8266WebServer` -> `HelloServer`.

2. Modify the Sketch:

- Update the `ssid` and `password` variables with your Wi-Fi credentials.

const char* ssid = "your_SSID";
const char* password = "your_PASSWORD";

3. Upload the Sketch:

- Connect your NodeMCU to your computer using a USB cable.

- Select the correct port under `Tools` -> `Port`.

- Click the upload button.

4. Monitor the Serial Output:

- Open the Serial Monitor (`Tools` -> `Serial Monitor`) and set the baud rate to `115200`.

- Once connected, the Serial Monitor will display the IP address of the NodeMCU.

5. Access the Server:

- Open a web browser and enter the IP address displayed in the Serial Monitor.

- You should see a message saying "Hello from ESP8266!".

Step 3: Set Up NodeMCU as a Client

1. Open the Example Sketch:

- Go to `File` -> `Examples` -> `ESP8266WiFi` -> `WiFiClient`.

2. Modify the Sketch:

- Update the `ssid` and `password` variables with your Wi-Fi credentials.

- Set the server's IP address and port (if you're using the previous server example, use the NodeMCU’s IP and port 80).

     const char* ssid = "your_SSID";
     const char* password = "your_PASSWORD";
     const char* host = "server_IP_address";
     const uint16_t port = 80;

3. Upload the Sketch:

- Connect your NodeMCU to your computer.

- Select the correct port and upload the sketch.

4. Monitor the Serial Output:

- Open the Serial Monitor and set the baud rate to `115200`.

- The NodeMCU will attempt to connect to the server and you should see the response from the server in the Serial Monitor.

Step 4: Testing and Further Development

- Testing:

- With the server running, reset the client NodeMCU and observe the communication between the server and client in the Serial Monitor.

- Further Development:

- Explore more examples and libraries to expand your IoT projects.

- Modify the server to handle different types of requests.

- Use the client to send sensor data to the server.