Arduino项目技术求助：蓝牙模块断开时LED闪烁/蜂鸣器触发代码

Hey there! I've got you covered with a straightforward implementation for your project. Below is the complete code, plus hardware setup details to make this work smoothly with either an LED or buzzer.

Hardware Setup #

First, let's get the wiring sorted:

• Bluetooth Module (HC-05/HC-06 example)
  • VCC → Arduino 5V (use 3.3V if your module is 3.3V-only—don't fry it!)
  • GND → Arduino GND
  • TX → Arduino Digital Pin 2 (we'll use SoftwareSerial to avoid blocking the hardware serial port)
  • RX → Arduino Digital Pin 3 (crossed with TX, standard for serial comms)
• LED or Buzzer
  • Positive terminal → Arduino Digital Pin 13 (add a 220Ω resistor for LED, 1kΩ resistor for buzzer)
  • Negative terminal → Arduino GND

Code Implementation #

This code listens for connection status messages from the Bluetooth module (most common modules like HC-05 send +CONNECT when paired, +DISCONNECT when the link drops). It then toggles your LED/buzzer accordingly:

#include <SoftwareSerial.h>

// Pin definitions
const int BT_TX_PIN = 2;
const int BT_RX_PIN = 3;
const int OUTPUT_PIN = 13; // Use this for either LED or buzzer

SoftwareSerial bluetoothSerial(BT_TX_PIN, BT_RX_PIN);
String incomingMsg = "";
bool isConnected = false;
unsigned long lastBlinkTime = 0;
const long blinkDelay = 500; // Blink/beep every 500ms

void setup() {
  pinMode(OUTPUT_PIN, OUTPUT);
  digitalWrite(OUTPUT_PIN, LOW); // Start with output off
  
  Serial.begin(9600); // Optional: for debugging via Serial Monitor
  bluetoothSerial.begin(9600); // Match your module's default baud rate
}

void loop() {
  // Read incoming data from Bluetooth module
  while (bluetoothSerial.available() > 0) {
    char c = bluetoothSerial.read();
    incomingMsg += c;
    
    // Check for connection status triggers
    if (incomingMsg.indexOf("+CONNECT") != -1) {
      isConnected = true;
      digitalWrite(OUTPUT_PIN, LOW); // Turn off LED/buzzer
      incomingMsg = ""; // Reset message buffer
    } else if (incomingMsg.indexOf("+DISCONNECT") != -1) {
      isConnected = false;
      incomingMsg = ""; // Reset message buffer
    }
  }

  // Handle blinking/buzzing when disconnected
  if (!isConnected) {
    unsigned long currentTime = millis();
    if (currentTime - lastBlinkTime >= blinkDelay) {
      lastBlinkTime = currentTime;
      // Toggle the output pin to create blink/beep effect
      digitalWrite(OUTPUT_PIN, !digitalRead(OUTPUT_PIN));
    }
  }
}

Quick Tips #

• Baud Rate Check: If your module isn't responding, double-check its default baud rate (HC-05 is often 9600, but some use 38400). Adjust bluetoothSerial.begin(XXX) to match.
• Buzzer Swap: No code changes needed—just replace the LED with a buzzer on OUTPUT_PIN. The toggle logic will make it beep on/off when disconnected.
• Debugging: If status messages aren't triggering, uncomment Serial.begin(9600) and use the Arduino Serial Monitor to see exactly what your Bluetooth module is sending. Some modules use different strings like "CONNECTED" instead of "+CONNECT".

内容的提问来源于stack exchange，提问作者Mohak