Need help with Nano HC-05 project

[horace]

for the Nano try this code

// Nano classic <> HC-05 Software Serial test

// using library instal AltSoftwareSerial 
// https://github.com/PaulStoffregen/AltSoftSerial

#include <AltSoftSerial.h>

// for loopback test connect pin D9 to pin D8

// for HC-05 shield connect
// Nano pin D9 TXD to HC-05 Rx  (note HC-05 uses 3.3V logic!!)
// Nano pin D8 RXD to HC-05 Tx 
// connect GND pins together and VCC to 5V
// NOTE: Tx and Rx pins are 3.3V logic level
// if connected to a 5V logic host (UNO, Mega, nANO, etc) 
//   use a level converter on host Tx to HC-05 Rx pin

// Connecting to Android phone
// on Powerup HC-05 LED should flash
// using Settings PAIR phone with HC-05
// when paired run Terminal app
//   e.g. https://play.google.com/store/apps/details?id=de.kai_morich.serial_bluetooth_terminal&hl=en-US
// set devices to Bluetooth Classic and select HC-05
// enter and receive text


// Set up a new SoftwareSerial object
AltSoftSerial HC_05_serial;//(rxPin, txPin);

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(115200);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }
  Serial.println();
  Serial.println("\n\nNano <> HC-05 SoftwareSerial test");
  // set the data rate for the SoftwareSerial port
  HC_05_serial.begin(9600);
 // HC_05_serial.println("Hello, world?");
}

void loop() { // run over and over
  if (HC_05_serial.available()) {
    Serial.write(HC_05_serial.read());
  }
  if (Serial.available()) {
    char ch=Serial.read();
    //Serial.write(ch);  // local echo if required
    HC_05_serial.write(ch);
  }
}

pair HC-05 with an Android phone
run a Bluetooth Terminal app, e.g. Serial Bluetooth Terminal
select HC-05 and transmit/receiver text

e.e. serial monitor output

Nano <> HC-05 SoftwareSerial test
hello from android
test2 1234456789
test3 agfyghjjgffh

Android phone display

photo of Nano/HC-05

the photo shows the potential divider (resistor 1K/2.2K ohm)

EDIT: potential divider input and output

one reason why I use ESP32 with onboard Bluetooth Classic is to get rid of the potential divider and interconnections