Receive a Long String with esp 01

Question

I have a esp 01(Wi-fi module) connected in my Arduino on port 2 and 3(TX RX), I can send a large String, but when I receive I can only receive at most 32 characters, here is the code of my Arduino:

#include <SoftwareSerial.h>

//TX RX
SoftwareSerial esp8266(2, 3);

void setup() {
    Serial.begin(9600);
    esp8266.begin(19200);
    ...
}

...


void loop() {

...

    if (esp8266.available() > 0) {

        String string = "";

        if (esp8266.find("[msg]:")) {
            string = esp8266.readStringUntil('\r');
        }

        /* Eu tentei desta forma também, mas o resultado foi o mesmo
        while (esp8266.available()) {
            string += (char) esp8266.read();
        }
        */

        Serial.print("\r\n" + string);  
    }

...

I am sending and receiving through this Python code the information:

import socket

class socketClient(object):
    socket = None

    def __init__(self, ip, port):
        self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.socket.connect(((ip, port)))

    def send(self, msg):
        self.socket.send(msg)

    def close(self):
        self.socket.close()

    def receive(self):
        return self.socket.recv(10240)

status = raw_input('Entre com o estado: ')
json = '[msg]:' + status + '\r\n';
print json

#This part was to test with a local server python
#socket = socketClient('127.0.0.1', 7000)

socketClient('192.168.0.43', 80)
socket.send(json)
msg = socket.receive()
print(msg.decode('utf-8'))
socket.close()

To make sure that the problem is in Arduino I did a local simulation using another Python code:

import socket

host = '127.0.0.1'
port = 7000
addr = (host, port)
serv_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
serv_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
serv_socket.bind(addr)
serv_socket.listen(10)
print 'aguardando conexao'
con, cliente = serv_socket.accept()
print 'conectado'
print "aguardando mensagem"
recebe = con.recv(1024)
print "mensagem recebida: "+ recebe
serv_socket.close()

And I got the whole string normally.

UPDATE

I did the following test by placing the module directly on TX RX ports and I sent the commands manually to connect to the network, and the string was (The one that came through Python), so the problem may be in door 2 and 3 of the Arduino that can not transmit all information as the RX TX port, or the Softwareserial library cannot capture every string, or what I hope it is, to catch the whole string requires a different method.

The bigger problem is I have no idea how I’m gonna do any type of test to verify what the real problem is.

UPDATE

I did the following test, this way I send directly to the serial monitor what I get from esp8266, and all characters are shown:

while (esp8266.available() > 0) {
    Serial.write(esp8266.read());
}

Somehow when trying to pass to String it cuts the information, I thought about the possibility of being the limit of the String object, but I did a test assigning the String directly and it also worked.

For some reason while making the conversion to String it ends up not getting all the information.

UPDATE

String buffer = "";

void loop() {
    if (esp8266.available() > 0) {
        buffer = esp8266.readStringUntil('\r');
    }
    if(buffer != ""){
        Serial.print("\r\n" + buffer);
    }
    buffer = "";
    delay(1000);
}

UPDATE

I did other tests, and managed to do the assignment of the full string in a variable, but the problem is the delay, but I don’t understand why, because it’s outside the while, I thought about the possibility of this passing twice in while and completing the string the second time it runs, but that’s not what happens, to do this test I put something to be printed outside the while and the information was printed apart from the complete string, that is to say he completed the while and then do another action, but when I put a delay it does not take the full string, which to me does not make any sense, since the delay is on the outside of the while, theoretically it was not to make a difference.

while (esp8266.available() > 0) {
    Serial.write(esp8266.read());
}
delay(1000);

Answer 1

Hi, I don’t work with ESP-01, just the Esp-8266 and Esp-32, but if you have the 32 byte limit, you can do the following:

• Set Python to send in 32-byte blocks (n or ( r n) will only go in the final block)

• And on Esp, this is what you do:

  void loop() {
  
      // Buffer de recepção de dados
  
      static String bufferRecSerial = ""; // Note que é static, senão o conteúdo é perdido entre um loop e outro
  
      ///.....
  
      // Recebimento de dados
  
      if (esp8266.available() > 0) {
  
          while (esp8266.available()) {
  
              char caract = (char) esp8266.read();
  
              if (caract == '\n') { // Nova linha
  
                  // Processa a mensagem (agora sem o \r\n)
  
                  if (bufferRecSerial.length() > 0) {
  
                     processarMensagem(bufferRecSerial);
  
                     // Zera o buffer
  
                     bufferRecSerial = "";
                  }
  
              } else if (caract != '\r') { // Ignora o \r
  
                // Adiciona no buffer // TODO: fazer logica de timeout se necessario
  
                bufferRec += caract;
  
              }
          }
      }
  }