Chronograph with Nextion

Projects Programming
1

Hello all.
I'm trying to display a chronograph on a Nextion monitor to count the "work time" of one machine. However if I have the display command on the Loop statement, the system "freezes" showing the time, and does not do anything else, like listening if a nextion button is pressed... I'm lost in what do to change that... any help?
This is what I have:

#include "Nextion.h"

NexDSButton bt0 = NexDSButton(0, 5, "luz");
NexText choras = NexText(0, 8, "Choras");
NexText cminutos = NexText(0, 9, "Cminutos");
NexText csegundos = NexText(0, 10, "Csegundos");

unsigned long over;
unsigned long timestart;
unsigned long timeend;
long hours = 0; // 3600000 milliseconds in an hour
long minutes = 0; // 60000 milliseconds in a minute
long seconds =  0; // 1000 milliseconds in a second
char buffer_temp[10] = {0};
char buffer_horas[10] = {0};
char buffer_minutos[10] = {0};
uint8_t buffer_second =0;


char buffer[100] = {0};

NexTouch *nex_listen_list[] = 
{
    &bt0,
    &bt1,
    NULL
};

// check dual state button and turn on or off one led
void bt0PopCallback(void *ptr)
{
    uint32_t dual_state;
    NexDSButton *btn = (NexDSButton *)ptr;
    memset(buffer, 0, sizeof(buffer));

    /* Get the state value of dual state button component . */
    bt0.getValue(&dual_state);
    if(dual_state) 
    {
        digitalWrite(2,HIGH);
        
    }
    else
    {
        digitalWrite(2,LOW);
    }
}
// check dual state button and turn on or off one led
void bt1PopCallback(void *ptr)
{
    uint32_t dual_state;
    NexDSButton *btn = (NexDSButton *)ptr;
    memset(buffer, 0, sizeof(buffer));

    /* Get the state value of dual state button component . */
    bt1.getValue(&dual_state);
    if(dual_state) 
    {
        digitalWrite(3,HIGH);
    }
    else
    {
        digitalWrite(3,LOW);
    }
}

void setup() {
      pinMode(2, OUTPUT);
      digitalWrite(2,LOW);
      pinMode(3, OUTPUT);
      digitalWrite(3,LOW);
      nexInit();
         
      bt0.attachPop(bt0PopCallback, &bt0);
      bt1.attachPop(bt1PopCallback, &bt1);
      timestart= millis(); // Start chrono
}

void loop() {
  nexLoop(nex_listen_list);
  displaycrono(); // display chrono (problematic part)
}

void displaycrono() {
        timeend = millis() - timestart;
        hours=int(timeend/3600000);
        over=timeend%3600000;
        minutes=int(over/60000);
        over=over%60000;
        seconds=int(over/1000);
       
        memset(buffer, 0, sizeof(buffer));
        memset(buffer_temp, 0, sizeof(buffer_temp));
        itoa(seconds, buffer_temp, 10);
        if (seconds < 10)
        {
        strcat(buffer, "0");
        }
        strcat(buffer, buffer_temp);
        if (strcmp(buffer_second, buffer))
        {
        csegundos.setText(buffer);
        }
        memset(buffer, 0, sizeof(buffer));
        memset(buffer_temp, 0, sizeof(buffer_temp));
        itoa(minutes, buffer_temp, 10);
        if (minutes < 10)
        {
        strcat(buffer, "0");
        }
        strcat(buffer, buffer_temp);
        if (strcmp(buffer_minutos, buffer))
        {
        cminutos.setText(buffer);
        }
        memset(buffer, 0, sizeof(buffer));
        memset(buffer_temp, 0, sizeof(buffer_temp));
        itoa(hours, buffer_temp, 10);
        if (hours < 10)
        {
        strcat(buffer, "0");
        }
        strcat(buffer, buffer_temp);
        if (strcmp(buffer_horas, buffer))
        {
        choras.setText(buffer);
        }
    }
2 
long hours = 0; // 3600000 milliseconds in an hour
long minutes = 0; // 60000 milliseconds in a minute
long seconds =  0; // 1000 milliseconds in a second

Those comments might as well be // Tom wore a blue suit, // Mary has red hair, and // Sally wore a green dress for all the relevance they have to the code that they (uselessly) follow.

What is the point of the strcmp() calls? You never assign new values to buffer_horas or buffer_minutos, so comparing the current contents of buffer to them is pointless.

Do you REALLY need a 100 element buffer to store the number of hours and minutes in, as text?

However if I have the display command on the Loop statement, the system "freezes" showing the time, and does not do anything else

Does the time change? Or, is the time only shown once? If the time keeps changing, then displaychrono() is being called repeatedly, and so, therefore, is nexLoop().