Documentation

// HC-05 Bluetooth - Arduino Echo Example
// Pair from your phone with "Serial Bluetooth Terminal" app
// Default PIN: 1234 (or 0000)

#include <SoftwareSerial.h>

// HC-05 TX -> D2, HC-05 RX (via divider) -> D3
SoftwareSerial bt(2, 3);

void setup() {
  Serial.begin(9600);
  bt.begin(9600);
  Serial.println("HC-05 ready. Pair and send text.");
}

void loop() {
  // Phone -> Arduino
  if (bt.available()) {
    String msg = bt.readString();
    Serial.print("Got: ");
    Serial.println(msg);
    bt.print("Echo: ");
    bt.println(msg);
  }
  // Arduino -> phone
  if (Serial.available()) {
    bt.write(Serial.read());
  }
}

// Configure HC-05 with AT commands
// 1. Wire EN/Key pin HIGH (3.3V) BEFORE powering the module
// 2. The LED should blink slowly (~2 Hz) instead of fast
// 3. Open Serial Monitor at 38400 baud, "Both NL & CR"
// 4. Type AT and you should see OK
//
// Common commands:
//   AT+NAME=MyHC05         (set device name)
//   AT+PSWD="2580"         (set pairing PIN)
//   AT+UART=115200,0,0     (change baud rate)
//   AT+ROLE=0              (slave) or AT+ROLE=1 (master)

#include <SoftwareSerial.h>
SoftwareSerial bt(2, 3);

void setup() {
  Serial.begin(38400);
  bt.begin(38400);
}

void loop() {
  if (bt.available()) Serial.write(bt.read());
  if (Serial.available()) bt.write(Serial.read());
}

#!/usr/bin/env python3
# Install: pip install pyserial
# Disable serial console first via raspi-config

import serial
import time

bt = serial.Serial('/dev/serial0', 9600, timeout=1)
bt.reset_input_buffer()

print("HC-05 ready - pair from phone, then send text")
while True:
    if bt.in_waiting:
        line = bt.readline().decode(errors='ignore').strip()
        print(f"Got: {line}")
        bt.write(f"Echo: {line}\n".encode())
    time.sleep(0.05)

# HC-05 on Pico - MicroPython Echo Example
from machine import UART, Pin
import time

uart = UART(0, baudrate=9600, tx=Pin(0), rx=Pin(1))
print("HC-05 ready")

while True:
    if uart.any():
        data = uart.readline()
        if data:
            text = data.decode().strip()
            print("Got:", text)
            uart.write("Echo: " + text + "\n")
    time.sleep_ms(50)