I have a java program on a computer that is the server and a program on the esp that acts as a client. They both connect to the local wifi and then to each other. The purpose is to have the computer send a number to the esp. I had managed to make them work, but then suddenly esp has stopped connecting to the server. I have spent quite some time trying to figure out what happened but I don't think I have changed anything. One day they all worked together, the next they didn't.
This is the main of my java code and I believe it works, even though it's probably not ideal (apart from this there are a couple of functions to make a small GUI and to do some actions):
createGUI();
//looking for the arduino port, to get data from it
SerialPort comPort = findArduinoPort();
if (comPort != null) {
System.out.println("Arduino port found: " + comPort.getSystemPortName());
} else {
System.out.println("Arduino port not found");
System.exit(0);
}
comPort.openPort();
comPort.setComPortTimeouts(SerialPort.TIMEOUT_READ_SEMI_BLOCKING, 0, 0);
InputStream inComPort = comPort.getInputStream();
ServerSocket listener = new ServerSocket(8020);
char lastRead;
String data = new String("0");
try{
while(true){
Thread.sleep(0);
if(myStatus == status.ON) {
//read data from aduino serial
if (inComPort.available() > 0) {
data = "";
while (true) {
lastRead = (char)inComPort.read();
if (lastRead == '\r') {
lastRead = (char)inComPort.read();
break;
} else {
data += lastRead;
}
}
}
System.out.println("Waiting for client");
//from my understanding the next line waits for the client to connect
Socket socket = listener.accept();
socket.setKeepAlive(true);
System.out.println("Client Connected");
try{
//i read data from the client, to make sure it's ready to receive
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
System.out.println("Client response: " + in.readLine());
//I send the data to esp8266
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
System.out.println("Sending Message: " + data);
out.write(data);
out.flush();
} catch (Exception e) {
e.printStackTrace();
} finally {
socket.close();
}
}
}
} finally {
try {
inComPort.close();
} catch (Exception e) {
e.printStackTrace();
}
comPort.closePort();
listener.close();
}
}
After writing to console "Waiting for client" it waits for a client to connect (and to my understanding it works fine). The problem comes with the code in esp8266
#include <ESP8266WiFi.h>
#include <LiquidCrystal.h>
//wifi data
#define NAME "i_put_my_wifi_here"
#define PASSWORD "i_put_my_wifi_pw_here"
String host = "i_put_my_computer_ip_here";
const int port = 8020;
WiFiClient client;
//lcd display to write the data to
LiquidCrystal lcd(D2, D3, D5, D6, D7, D8);
void setup() {
Serial.begin(115200);
//lcd setup
lcd.begin(16, 2);
lcd.print("Puntamenti:");
lcd.setCursor(0, 1);
lcd.print("0");
WiFi.mode(WIFI_STA);
WiFi.begin(NAME, PASSWORD);
Serial.print("\nConnecting to wifi");
while(WiFi.status() != WL_CONNECTED)
{
delay(500);
Serial.print(".");
}
Serial.println();
Serial.println("Connected\n");
}
void loop() {
//i try to conect to the server
if (client.connect(host, port))
{
Serial.print("Connected to host: ");
Serial.println(host);
//i tell the server i'm ready for data
client.println("Connected");
Serial.print("Wating for data");
int i = 0;
while(true){
if(client.available() == 0){
Serial.print(".");
i++;
if(i >= 10){
break;
}
delay(1000);
} else {
lcd.setCursor(0, 1);
String streamData = client.readStringUntil('\n');
lcd.print(streamData);
Serial.print("\nData received: ");
Serial.println(streamData);
break;
}
}
client.stop();
} else {
Serial.println("Connection to host failed");
}
delay(1000);
}
So my problem comes with client.connect(host, port). Last time i tried the programs it worked fine. It returned true and the rest would happen. Since today, however it's always false, so esp connects to the wifi, like the computer, but then it always fails to connect to the server waiting for it. I can't understand where's the problem, and especially how it can be that it used to work well and now it doesn't anymore.
