CODEWITHSUNDEEP
c#xamarinxamarin.formsarduinobluetooth-lowenergy
Raul
Raul

Reputation: 61

Send string to HM-10 ble in arduino from xamarin app and receiving different one

I am trying to do a tx(pc)-rx(arduino), tx(arduino)-rx(pc) connection, sending a string "Hello World!:)" from the client in xamarin.forms, in order to receive the same string decoded from serial port with BLE. At the moment I send the string, it works well, due to the fact that I see perfectly the string on Serial Monitor of arduino, but when decoded, the string is not the same as the sended.

Codes: Arduino:

void loop(){
  if (BT.available() > 0 ){

    c = BT.readString();
    
    str_len = c.length() +1;
    char char_array[str_len];
    c.toCharArray(char_array, str_len);
    int i = 0;
    while(i<str_len){
      char_array_aux[i] = char_array[i];
      i++;
    }
    char_array_aux[str_len] = "\n";
    
   
      }
     
      int i = 0;
      while(i<str_len){
        if(char_array_aux[i] == "\n")
          BT.end();
        BT.print(char_array_aux[i]);
        i++;

      }
      
      
    
  }

Xamarin.forms app send/receive message function:

public async Task sendAndReceiveString()
        {
            //Guid characteristics =    Id  {0000ffe1-0000-1000-8000-00805f9b34fb}  System.Guid
            //Guid services =   Id  {0000ffe0-0000-1000-8000-00805f9b34fb}  System.Guid

            var stringToSend = "Hello World! :)";
            var services = await deviceConn.GetServicesAsync();
            IService service = services[0];
            var characteristics = await service.GetCharacteristicsAsync();
            var characteristic = characteristics[0];
            try
            {

                //Write message
                byte[] bytes = Encoding.ASCII.GetBytes(stringToSend);
                
                await characteristic.WriteAsync(bytes);

                //Read Message
                

                byte[] answ = await characteristic.ReadAsync();
                string answ_str = Encoding.ASCII.GetString(answ);
                


                msgSended = "Message sended:" + stringToSend;
              
               
                        msgReceived = "Message received: " + answ_str;
            }

Debug log:

Sended string: Hello world! :) 

Received string: Hello world! :)
Hello world! :)
He

I do not know how to work properly with bluetooth buffer. If anybody knows, let me know it please.

Thank you in advance.

Regards, Raúl.

Upvotes: 0

Views: 423

Answers (1)

Raul
Raul

Reputation: 61

I just fixed it! I just used BT.readStringUntil("\n"); instead of readString()

and buffer does not overflow.

Upvotes: 2

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