BT new 11 with board manager downgrade

// This example code is in the Public Domain (or CC0 licensed, at your option.)
// By Victor Tchistiak - 2019
//
// This example demonstrates master mode Bluetooth connection to a slave BT device using PIN (password)
// defined either by String "slaveName" by default "OBDII" or by MAC address
//
// This example creates a bridge between Serial and Classical Bluetooth (SPP)
// This is an extension of the SerialToSerialBT example by Evandro Copercini - 2018
//
// DO NOT try to connect to phone or laptop - they are master
// devices, same as the ESP using this code - it will NOT work!
//
// You can try to flash a second ESP32 with the example SerialToSerialBT - it should
// automatically pair with ESP32 running this code

// Downgrade to esp 2.0.17 in board manager

#include "BluetoothSerial.h"

#define CORE_DEBUG_LEVEL ARDUHAL_LOG_LEVEL_INFO  // show logs

//#define USE_NAME           // Comment this to use MAC address instead of a slaveName
const char *pin = "1234";  // Change this to reflect the pin expected by the real slave BT device

#if !defined(CONFIG_BT_SPP_ENABLED)
#error Serial Bluetooth not available or not enabled. It is only available for the ESP32 chip.
#endif

BluetoothSerial SerialBT;

#ifdef USE_NAME
String slaveName = "EMUCANBT_SPP";  // Change this to reflect the real name of your slave BT device
#else
String MACadd = "AA:BB:CC:11:22:33";                          // This only for printing
uint8_t address[6] = { 0xAA, 0xBB, 0xCC, 0x11, 0x22, 0x33 };  // Change this to reflect real MAC address of your slave BT device
#endif

String myName = "ESP32-BT-Master";

void setup() {
  bool connected;
  Serial.begin(921600);  // Faster serial. Increase serial monitor speed

  SerialBT.begin(myName, true);
  Serial.printf("The device \"%s\" started in master mode, make sure slave BT device is on!\n", myName.c_str());

#ifndef USE_NAME
  SerialBT.setPin(pin);
  Serial.println("Using PIN");
#endif

// connect(address) is fast (up to 10 secs max), connect(slaveName) is slow (up to 30 secs max) as it needs
// to resolve slaveName to address first, but it allows to connect to different devices with the same name.
// Set CoreDebugLevel to Info to view devices Bluetooth address and device names
#ifdef USE_NAME
  connected = SerialBT.connect(slaveName);
  Serial.printf("Connecting to slave BT device named \"%s\"\n", slaveName.c_str());
#else
  connected = SerialBT.connect(address);
  Serial.print("Connecting to slave BT device with MAC ");
  Serial.println(MACadd);
#endif

  if (connected) {
    Serial.println("Connected Successfully!");
  } else {
    while (!SerialBT.connected(30000)) {
      Serial.println("Failed to connect. Make sure remote device is available and in range, then restart app.");
    }
  }
  // Disconnect() may take up to 10 secs max
  if (SerialBT.disconnect()) {
    Serial.println("Disconnected Successfully!");
  }
  // This would reconnect to the slaveName(will use address, if resolved) or address used with connect(slaveName/address).
  SerialBT.connect();
  if (connected) {
    Serial.println("Reconnected Successfully!");
  } else {
    while (!SerialBT.connected(10000)) {
      Serial.println("Failed to reconnect. Make sure remote device is available and in range, then restart app.");
    }
  }
}

void loop() {
 // if (Serial.available()) {
 // 	SerialBT.write(Serial.read());
 // }
  if (SerialBT.available()) {
    // Serial.write(SerialBT.read());
	// char incoming = SerialBT.read();
    // Serial.printf("Received: %02X\n", incoming);  // Print HEX value of received data
    // Serial.write(incoming);
	  uint8_t incoming = SerialBT.read();  // Read one byte
      Serial.printf("%02X ", incoming);    // Print as HEX
  }
  //delay(40);
}

//Option #2
/*
void loop() {
    uint8_t frame[5];  // Buffer for one full data frame

    // Wait until at least 5 bytes are available
    while (SerialBT.available() >= 5) {
        SerialBT.readBytes(frame, 5);  // Read exactly 5 bytes

        // Validate IDCHAR (should always be 0xA3)
        if (frame[1] != 0xA3) {
            Serial.println("Invalid frame: IDCHAR mismatch!");
            return;
        }

        // Calculate checksum
        uint8_t checksum = (frame[0] + frame[1] + frame[2] + frame[3]) % 255;
        if (checksum != frame[4]) {
            Serial.println("Checksum error!");
            return;
        }

        // Extract values
        uint8_t channel = frame[0];
        uint16_t value = (frame[2] << 8) | frame[3];  // Combine High and Low byte

        Serial.printf("Channel: %d, Value: %d\n", channel, value);
    }
}
*/