I cant concatenate when pox.update() of MAX30100 library is in Arduino loop

Question

Hello friends of the community. I spend a lot of time trying to solve this issue and I hope you can help me. I'm ussing the library from this link https://github.com/oxullo/Arduino-MAX30100 in order to implement my project. The arduino code executes quite well, but when I try to receive data from the serial port, who's connected to an HC-05, I can't concatenate the data when pox.update() is present in the loop, the data received is like:

R
o
b
e
r
t
o
 
A
n
d
r
e
s

So I need to cancatenate it to shows it in a 128x64 oled display. Moreover, the if (incomingByte == 'T') condition seems not to be executed, as it the oled display doesn't show the getStringfromProgMem(3) char. The loop code is:

  void loop() {
  if (Serial.available() > 0) {
    incomingByte = Serial.read();
    if (incomingByte == 'T') {
      palabra = getStringfromProgMem(3);
      c = 0;
    } else {
      palabra.concat(incomingByte); 
    }
  }
  pox.update();
  display.clearDisplay();
  estado = digitalRead(STATE);
  estado ? (enlace()) : (noenlace());
  unsigned long tiempoActual = millis();
  if (tiempoActual - tiempoAnterior >= intervaloEvento) {
    rate = pox.getHeartRate();
    spo = pox.getSpO2();
    if (rate && palabra != getStringfromProgMem(3)) {
      c++;
    }
    if (c == 60) {
      c = 0;
    }
    /*Serial.print(rate);
    Serial.print(',');
    Serial.print(spo);
    Serial.print(',');
    Serial.println(c);*/
    tiempoAnterior = tiempoActual;
  }
  mostrar(rate, 15, 35);
  mostrar(spo, 105, 35);
  mostrar(getStringfromProgMem(0), 10, 52);
  mostrar(getStringfromProgMem(1), 100, 52);

  /*outputValue = (VERF * analogRead(ANALOG)) / 1024;
    smoothedVal = smoothedVal + ((outputValue - smoothedVal) / SAMPLES);
    comparacion(smoothedVal);*/
  //
  display.display();
}

The code shows just the first letter in the oled display and ignores the others. I'm using this libraries also:

#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include "MAX30100_PulseOximeter.h"
#include <avr/pgmspace.h>

And I declarate the variables "incomingByte" and "palabra" as globals:

char incomingByte;
String palabra="";

The code palabra.concat(incomingByte) executes well without the "pox.update()" method. What I'm doing wrong?

Answer 1

I think that I solved it. The issue was generated due a memory leak of my Arduino. When I tried to concatenate the String "palabra", the Arduino simply didn't do it because of a memory leak. If any of you have troubles handling the Strings and the Arduino simply doesn't concatenate your strings, I suggest visit this site:

https://www.best-microcontroller-projects.com/arduino-string.html

Now I can't realice how to handle the c-strings but is question of time.

Any of you have an idea how to clean the static char palabra[15], *pSdata = palabra;?

When I use strings is simply to write palabra="";. But now, I have no idea how to do it. I hope you can help me.

Greetings.