ESP32 Bluetooth transmission problem

[cola]

I used a simple example to test Bluetooth transmission, and everything worked fine. I think this may be related to the fact that serialBT.write() does not have its own delimiter when writing, because the data I see on the serial monitor is continuous.
The example to test Bluetooth transmission code:

#include "BluetoothSerial.h"

BluetoothSerial SerialBT;

// define deviceName
const char *deviceName = "ESP32_BT_Example";

// counter
int count = 0;

void setup() {
  Serial.begin(115200);
  
  // initial Bluetooth
  if (!SerialBT.begin(deviceName)) {
    Serial.println("Bluetooth initialization failed!");
    while (1);
  }
  
  Serial.println("Bluetooth is activated, waiting for connection...");
  Serial.print("deviceName：");
  Serial.println(deviceName);
}

void loop() {
  // waiting for connection
  if (SerialBT.connected()) {
    // send data 
    String message = "Hello World #" + String(count++);
    SerialBT.println(message);
    
    Serial.println("sendmessage：" + message);
    senddata();
  } else {
    Serial.println("waiting for connection...");
  }

  delay(1000);  
}
void senddata(){
  const char DataPacketHeader[5] = {0x01, 0x02, 0x03, 0x04, 0x05};
  for (int i = 0; i < 5; i++) {
      SerialBT.write(DataPacketHeader[i]);
  } 
  SerialBT.write(0x0A); 
}

In addition, I also saw that the transmission packet on the Bluetooth transmission serial port complies with the transmission protocol.
This may be back to the previous transmission protocol problem.