HC-05 + AtTiny85 - test sketch

attinyhc05.ino

// Author: martinius96
// Support: https://www.paypal.me/Chlebovec
// Personal web: https://arduino.php5.sk
// Email: martinius96@gmail.com
#define RX 3
#define TX 4
#define pinLED 0
#include <SoftwareSerial.h>
SoftwareSerial bluetooth(TX, RX);

void setup() {
  bluetooth.begin(9600);
 pinMode(pinLED, OUTPUT);
}

void loop() {
  byte BluetoothData;
 if (bluetooth.available() > 0) {
    
    BluetoothData=bluetooth.read();
    switch (BluetoothData) {
      case '0':
      digitalWrite(pinLED, LOW);
        bluetooth.println("Turn off LED");
        break;
      case '1':
       digitalWrite(pinLED, HIGH);
        bluetooth.println("Turn on LED");
        break;
      case 'c':
        bluetooth.print("System running: ");
        bluetooth.print(millis()/1000);
        bluetooth.println(" seconds.");
        break;
      case '\r':
        break;
      case '\n':
        break;
      default:
        bluetooth.println("Unsupported command.");
    }
  }
  delay(100);
}