Eva Tuecke

Networking

Assignment: design, build, and connect wired or wireless node(s) with network or bus addresses and local input &/or output device(s)

For this week's assignment, I set up a super simple Flask server. I wrote a quick script server.py to create the server (run with python server.py):

    from flask import Flask, jsonify

    app = Flask(__name__)

    @app.route('/message', methods=['GET'])
    def message():
        return jsonify({"message": "Hello!"})

    # Run server
    if __name__ == '__main__':
        app.run(host='0.0.0.0', port=8080)

                

This server is part of the networked system, and will be the communication endpoint for a ESP32-c3 node. The server has a network address, making it addressable within the local network. I then set up the ESP32-c3 to connect to wifi, establishing the ESP32-c3 as a node on the network. This way it can communicate with other nodes. The code uploaded onto the ESP32-c3:

    #include <WiFi.h>
    #include <HTTPClient.h>
        
    const char* ssid = "XXX"; 
    const char* password = "XXX"; 
    const char* serverURL = "XXX";
        
    void setup() {
        Serial.begin(115200);
        WiFi.begin(ssid, password);
        while (WiFi.status() != WL_CONNECTED) {
            delay(1000);
            Serial.println("Connecting to WiFi...");
        }
        Serial.println("Connected to WiFi");
    }
        
    void loop() {
        if (WiFi.status() == WL_CONNECTED) {
            HTTPClient http;
            http.begin(serverURL);
            int httpCode = http.GET();
            if (httpCode > 0) {
                String payload = http.getString();
                Serial.println("Response:");
                Serial.println(payload);
            } else {
                Serial.println("Error on HTTP request");
            }
            http.end();
        }
        delay(10000); // Wait 10 seconds between requests
    }
               
                

With this code, the esp32-c3 connects to the wifi network, and then sends a GET request to the server every 10 seconds. The response from the server is printed to the serial monitor (a local output device). You can see below that this works:

When I stop the server, I correctly get an error message: "Error on HTTP request".