ESP8266 IoT Remote Buzzer Alarm

By Idlan Zafran Mohd Zaidie

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📌 Overview

A smart, cloud-connected alarm system built for the ESP8266. This project monitors remote sensor values against customizable thresholds using the ThingsSentral IoT platform and triggers a local physical buzzer and LED sequence when conditions are met. It also features a built-in battery monitoring system and a robust Wi-Fi configuration portal.

Features

• Cloud-Synced Alarms: Automatically triggers when remote sensor data exceeds predefined conditions, or can be triggered manually via the ThingsSentral dashboard.
• Battery Monitoring System: Reads external battery voltage via a voltage divider and visually indicates battery health using 3 LEDs. Automatically mutes the buzzer if the battery reaches a critical level to conserve power.
• Smart Wi-Fi Provisioning: Utilizes RapidBootWiFi to easily configure network credentials and IoT device IDs via a captive web portal, avoiding hardcoded Wi-Fi passwords.
• Offline Fallback: Features a visual LED "heartbeat" to let you know the device is functioning even if it loses connection to the server.
• Non-Blocking Logic: Uses Ticker.h for asynchronous background tasks like buzzer toggling and status animations.

Hardware Requirements

• ESP8266 Development Board (e.g., NodeMCU or Wemos D1 Mini)
• 1x Active Buzzer
• 3x LEDs (Preferably different colors for battery levels)
• Resistors for LEDs (e.g., 220Ω or 330Ω)
• Resistors for Voltage Divider: 1x 10kΩ and 1x 4.7kΩ
• Power Source (e.g., 9V Battery or 3x Li-Po cells)

Pin Mapping

Component	ESP8266 Pin	Notes
LED 1 (Low)	GPIO 14 (D5)	Blinks fast when battery is critical
LED 2 (Mid)	GPIO 12 (D6)
LED 3 (High)	GPIO 13 (D7)
Buzzer	GPIO 5 (D1)	Active Low configuration
Battery Monitor	A0	Connected via 10kΩ / 4.7kΩ voltage divider
Setup Button	GPIO 0 (D3/FLASH)	Hold during boot to open Wi-Fi portal

Software Dependencies

To compile this project, you will need the Arduino IDE or PlatformIO with the ESP8266 core installed, along with the following libraries:

• Ticker.h (Built-in with ESP8266 core)
• RapidBootWiFi
• ThingsSentral

Installation & Setup

1. Clone the Repository

   git clone https://github.com/YOUR_USERNAME/esp8266-iot-remote-buzzer-alarm.git

2. Security Note: Configure Credentials By default, the code uses placeholder values for the ThingsSentral IDs. Do not commit your real IDs to GitHub. When flashing to your device, replace the placeholders in the Config namespace with your actual credentials, or input them via the Wi-Fi Setup Portal.

char userID[16]      = "YOUR_USER_ID";
char sensorID[32]    = "YOUR_SENSOR_ID";   
char buzzerID[32]    = "YOUR_BUZZER_ID";
char conditionID[32] = "YOUR_CONDITION_ID";

3. Upload to ESP8266 Compile and upload the code to your board.

4. Wi-Fi & Device Configuration

   • Upon first boot, the device will fail to connect to Wi-Fi and broadcast an Access Point named Remote_Buzzer_Alarm.
   • Connect to this AP using your phone or computer.
   • A captive portal will appear. Enter your local Wi-Fi SSID, Password, and your ThingsSentral IDs.
   • Click Save. The device will reboot and connect to the cloud.
   • Note: You can force this portal to open at any time by holding down the BOOT/FLASH button (Pin 0) while powering on the device.

Battery LED Behavior

State	Voltage	LED Indicator
Full	≥ 9.6V	3 LEDs ON
Medium	9.3V - 9.59V	2 LEDs ON
Low	9.1V - 9.29V	1 LED ON
Critical	< 9.1V	1 LED blinking fast (Buzzer is muted)

License

This project is licensed under the MIT License.