 void b0PopCallback(void *ptr);
 void b1PopCallback(void *ptr);
 
+/*
+ * Declare a text object [page id:0,component id:1, component name: "t0"]. 
+ */
 NexText t0 = NexText(0, 1, "t0");
+
+/*
+ * Declare a button object [page id:0,component id:2, component name: "b0"]. 
+ */
 NexButton b0 = NexButton(0, 2, "b0");
+
+/*
+ * Declare a button object [page id:0,component id:3, component name: "b1"]. 
+ */
 NexButton b1 = NexButton(0, 3, "b1");
 
 char buffer[100] = {0};
 
+/*
+ * Register object t0, b0, b1, to the touch event list.  
+ */
 NexTouch *nex_listen_list[] = 
 {
     &t0,

    t0.setText(buffer);
}

void b1PopCallback(void *ptr)
{
    uint16_t len;


void setup(void)
{
    /* Set the baudrate which is for debug and communicate with Nextion screen. */
    nexInit();

    /* Register the pop event callback function of the current text component. */
    t0.attachPop(t0PopCallback);

    /* Register the pop event callback function of the current button0 component. */
    b0.attachPop(b0PopCallback);

    /* Register the pop event callback function of the current button1 component. */
    b1.attachPop(b1PopCallback);

    dbSerialPrintln("setup done");
}

void loop(void)
{
    /*
     * When a pop or push event occured every time, 
     * the corresponding component[right page id and component id] in touch event list will be asked.
     */
    nexLoop(nex_listen_list);
}

