ESP32 Refuse Connection and Unable to send data to Android App

Projects Networking, Protocols, and Devices
1

ESP32 Serial Monitor Status:

ets Jul 29 2019 12:21:46

rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0030,len:1448
load:0x40078000,len:14844
ho 0 tail 12 room 4
load:0x40080400,len:4
load:0x40080404,len:3356
entry 0x4008059c
Connecting to Wi-Fi...
.Connected to Wi-Fi
IP Address: 192.168.1.10
Received JSON data: Found ID #3 with confidence of 92

Received JSON data: Found ID #6 with confidence of 131

Received JSON data: Election Results

Received JSON data: PTI:

Received JSON data: 1

Received JSON data: PPP:

Received JSON data: 0

Received JSON data: ANP:

Received JSON data: 0

Received JSON data: TotalVotes:

Received JSON data: 1

Received JSON data: Winner: PTI

Received JSON data: (100.00% of total votes)

Received JSON data: Sending JSON data: {"totalVotes":1,"PTI":1,"PPP":0,"ANP":0,"winner":"PTI"}

Received JSON data:

Failed to parse JSON: EmptyInput
Received JSON data: {"totalVotes":1,"PTI":1,"PPP":0,"ANP":0,"winner":"PTI"}
Parsed data:
Total Votes: 1
PTI Votes: 1
PPP Votes: 0
ANP Votes: 0
Winner: PTI
Sending data to server: totalVotes=1&PTI=1&PPP=0&ANP=0&winner=PTI
Error code: -1
Error message: connection refused

**ESP32 Code:**

```
`#include <WiFi.h>`
#include <HTTPClient.h>
#include <ArduinoJson.h>

// Wi-Fi credentials
const char* ssid = "^__Encrypted Air__^";
const char* password = "S3curP@ssW1f1";

// Server URL for sending data
const String serverUrl = "http://192.168.1.10/results.json";

// Buffer size for incoming serial data
const int bufferSize = 256;

// Global variables for storing results
int totalVotes = 0;
int PTI = 0;
int PPP = 0;
int ANP = 0;
String winner_name = "";

// Initialize Serial communication
void setup() {
  Serial.begin(115200); // Initialize serial communication with Arduino
  WiFi.begin(ssid, password);

  Serial.println("Connecting to Wi-Fi...");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("Connected to Wi-Fi");

  Serial.print("IP Address: ");
  Serial.println(WiFi.localIP());
}

void loop() {
  // Check if there is incoming data from Arduino
  if (Serial.available()) {
    char jsonBuffer[bufferSize];
    int bytesRead = Serial.readBytesUntil('\n', jsonBuffer, bufferSize - 1);
    jsonBuffer[bytesRead] = '\0'; // Null-terminate the string

    // Print the received data for debugging
    Serial.print("Received JSON data: ");
    Serial.println(jsonBuffer);

    // Parse the JSON data
    StaticJsonDocument<bufferSize> doc;
    DeserializationError error = deserializeJson(doc, jsonBuffer);

    if (error) {
      Serial.print("Failed to parse JSON: ");
      Serial.println(error.c_str());
      return;
    }

    // Extract data from JSON
    if (doc.containsKey("totalVotes") && 
        doc.containsKey("PTI") && 
        doc.containsKey("PPP") && 
        doc.containsKey("ANP") && 
        doc.containsKey("winner")) {
      
      totalVotes = doc["totalVotes"];
      PTI = doc["PTI"];
      PPP = doc["PPP"];
      ANP = doc["ANP"];
      winner_name = doc["winner"].as<String>();

      // Print the parsed values for debugging
      Serial.println("Parsed data:");
      Serial.print("Total Votes: ");
      Serial.println(totalVotes);
      Serial.print("PTI Votes: ");
      Serial.println(PTI);
      Serial.print("PPP Votes: ");
      Serial.println(PPP);
      Serial.print("ANP Votes: ");
      Serial.println(ANP);
      Serial.print("Winner: ");
      Serial.println(winner_name);

      // Send data to the Android application
      sendToAndroidApp(totalVotes, PTI, PPP, ANP, winner_name);
    } else {
      Serial.println("JSON is missing some expected fields.");
    }
  }

  delay(10000); // Wait for 10 seconds before checking again
}

void sendToAndroidApp(int totalVotes, int PTI, int PPP, int ANP, String winner_name) {
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    http.begin(serverUrl);
    http.addHeader("Content-Type", "application/x-www-form-urlencoded");

    String httpRequestData = "totalVotes=" + String(totalVotes) + 
                             "&PTI=" + String(PTI) + 
                             "&PPP=" + String(PPP) + 
                             "&ANP=" + String(ANP) + 
                             "&winner=" + winner_name;

    Serial.print("Sending data to server: ");
    Serial.println(httpRequestData);

    int httpResponseCode = http.POST(httpRequestData);

    if (httpResponseCode > 0) {
      String response = http.getString();
      Serial.print("Server response: ");
      Serial.println(response);
    } else {
      Serial.print("Error code: ");
      Serial.println(httpResponseCode);
      Serial.print("Error message: ");
      Serial.println(http.errorToString(httpResponseCode));
    }

    http.end();
  } else {
    Serial.println("Error: Not connected to Wi-Fi");
  }
}
```
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
**Android Activity Code**

```
public class UserActivity extends AppCompatActivity {

    private WebView webView;
    private Button logoutButton;
    private RequestQueue requestQueue;
    private static final String RESULTS_URL = "http://192.168.1.10/results.json"; // Replace with your actual URL

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_user);

        // Initialize components
        webView = findViewById(R.id.results_webview);
        logoutButton = findViewById(R.id.user_logout_button);
        requestQueue = Volley.newRequestQueue(this);

        // Setup WebView
        WebSettings webSettings = webView.getSettings();
        webSettings.setJavaScriptEnabled(true);
        webView.setWebViewClient(new WebViewClient());

        // Load Election Results from the server
        fetchElectionResults();

        // Logout button functionality
        logoutButton.setOnClickListener(v -> {
            Intent intent = new Intent(UserActivity.this, Login.class);
            startActivity(intent);
            finish();
        });
    }

    private void fetchElectionResults() {
        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(
                Request.Method.GET,
                RESULTS_URL,
                null,
                new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {
                        String htmlData = formatElectionResult(response);
                        webView.loadDataWithBaseURL(null, htmlData, "text/html", "UTF-8", null);
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Toast.makeText(UserActivity.this, "Failed to load results", Toast.LENGTH_SHORT).show();
                    }
                }
        );
        requestQueue.add(jsonObjectRequest);
    }

    private String formatElectionResult(JSONObject json) {
        try {
            StringBuilder html = new StringBuilder();
            html.append("<html><body>")
                    .append("<h2>Election Results</h2>")
                    .append("<table border='1' style='width:100%; border-collapse: collapse;'>")
                    .append("<tr><th>Party</th><th>Votes</th><th>Percentage</th></tr>");

            html.append("<tr><td>PTI</td><td>").append(json.getInt("PTI")).append("</td><td>").append(json.getJSONObject("Percentages").getString("PTI")).append("</td></tr>")
                    .append("<tr><td>PPP</td><td>").append(json.getInt("PPP")).append("</td><td>").append(json.getJSONObject("Percentages").getString("PPP")).append("</td></tr>")
                    .append("<tr><td>ANP</td><td>").append(json.getInt("ANP")).append("</td><td>").append(json.getJSONObject("Percentages").getString("ANP")).append("</td></tr>")
                    .append("</table>")
                    .append("<p>Total Votes: ").append(json.getInt("TotalVotes")).append("</p>")
                    .append("<h3>Winner: ").append(json.getString("Winner")).append("</h3>")
                    .append("</body></html>");

            return html.toString();
        } catch (Exception e) {
            e.printStackTrace();
            return "<html><body><p>Error loading results</p></body></html>";
        }
    }

}
```
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