PlatformIO_ESP32_BluetoothSerialLogging/src/main.cpp

/*
This is to route the serial logs from a device to serial bluetooth for convenient monitoring.
Doit DevKitV1 - Connect Serial port 2 (GPIO17/GPIO16) to the device you want to monitor.
On the phone, connect to the ESP32_Logger and use the "Serial Bluetooth Terminal" app to show the logs.
*/

#include <Arduino.h>
#include "BluetoothSerial.h" //Header File for Serial Bluetooth, will be added by default into Arduino
BluetoothSerial ESP_BT; //Object for Bluetooth

bool isLogging;

void setup() {
  Serial.begin(9600); //Start Serial monitor in 9600
  ESP_BT.begin("ESP32_Logger"); //Name of your Bluetooth Signal
  Serial.println("Bluetooth Device is Ready to Pair");
  pinMode (LED_BUILTIN, OUTPUT);//Specify that LED pin is output

  Serial2.begin(9600); // points to Serial port 2 (GPIO17 / GPIO16)

  isLogging=false;
}

void loop() {
  if (ESP_BT.available()) { //Check if we receive anything from Bluetooth
    int incoming = ESP_BT.read(); //Read what we recevive 
    Serial.print("Received:"); Serial.println(incoming);
    if (incoming == 49) {
        digitalWrite(LED_BUILTIN, HIGH);
        isLogging=true;
        ESP_BT.println("Logging turned ON");
    }

    if (incoming == 48) {
        digitalWrite(LED_BUILTIN, LOW);
        isLogging=false;
        ESP_BT.println("Logging turned OFF");
    }     

    if (incoming == 57) {
        ESP_BT.println("Free memory: " + String(esp_get_free_heap_size()) + " bytes");
    }     
      
    if(Serial2.available() && isLogging){
      String incomingData = Serial2.readStringUntil('\n');
      ESP_BT.println(incomingData);
    }
  }

  delay(100);
}