Published August 24, 2023

Key Finder with the Xiao NRF52840 Module

Losing keys can be a frustrating experience that disrupts our daily routines. It's over!

IntermediateFull instructions provided2 hours8,368

Key Finder with the Xiao NRF52840 Module

Things used in this project

Hardware components

Seeed Studio Seeed XIAO BLE nRF52840 Sense

Buzzer

LED

Software apps and online services

Nordic Semiconductor nRF Connect SDK

Seeed Fusion

Story

Introduction:

Wave goodbye to the eternal struggle of lost keys, for technology and innovation have united to provide a solution. Thanks to the collaborative efforts of Seeed Studio company, a remarkable key finder has emerged. Harnessing the power of Bluetooth Low Energy (BLE), this device syncs with smartphones, featuring a buzzer and LED that gracefully guide users to their elusive keys. In this article, we delve into the development of this smart key finder powered by the Xiao NRF52840 module, shed light on its pivotal features, and extend heartfelt gratitude to Seeed Studio for their unwavering support.

Core Components and Purpose:

Nestled at the core of this ingenious key finder is the Xiao NRF52840 module, a compact powerhouse boasting an ARM Cortex-M4 processor primed for BLE communication. Complementing this module are the essential components:

Buzzer: Emitting a distinct sound, the buzzer serves as a beacon, aiding in the swift location of keys, even when they play hide and seek.
LED: In dim environments, the LED shines brightly, illuminating the path to the missing keys and ensuring they are found with ease.
Button: A simple yet powerful component, the button is assigned the task of deactivating the buzzer and LED once the keys have been located.

Crafting the Key Finder:

Hardware Configuration: The intricately designed PCB layout seamlessly integrates the Xiao NRF52840 module, meticulously connecting GPIO pins to the buzzer, LED, and button. A solid network of power and ground connections forms the bedrock. This PCB board is sponsored by Seeed Fusion. They offer one-stop prototyping services for PCB manufacture and PCB assembly, and they take care of the entire fabrication process, from PCB manufacturing and parts sourcing to assembly and testing services, so you can get a quality product.
Program Logic with Arduino IDE: Leveraging the versatile Arduino IDE, the firmware takes shape, focusing on robust BLE functionality that facilitates seamless communication with smartphones.
BLE Synchronization: Whether via the NRF Connect app, the key finder establishes a BLE connection with smartphones, creating a conduit for transmitting commands.
Command Execution: The firmware's brilliance lies in its ability to execute designated commands upon receiving signals from the smartphone. This triggers the activation of the buzzer and LED, guiding users to their keys.
Efficient Power Management: To extend the life of the battery, the firmware incorporates intelligent power-saving mechanisms, ensuring the module switches to a low-power mode during periods of dormancy.

Operational Symphony:

BLE Pairing: Armed with the NRF Connect app, the smartphone detects the key finder's presence and establishes a BLE connection, creating a seamless avenue for communication.
Command Transmission: Smartphone apps deftly transmit predetermined commands to the key finder, triggering the buzzer and LED to provide cues for locating the keys.
Effortless Discovery: Users need only follow the audible cues and the guiding light of the LED to quickly and efficiently locate their keys, rendering frantic searches a thing of the past.

Advantages and Real-world Scenarios:

Elegance in Simplicity: The key finder's straightforward design underscores technology's ability to address everyday challenges.
Tailored User Experience: Customizable firmware empowers users to fine-tune sound and light patterns to their liking.
Adaptable Design: With potential for integrating additional sensors, the key finder remains future-ready and versatile.
Emergency Assistance: Beyond its primary role, this device can also serve as an SOS beacon during critical situations.

Conclusion:

The key finder, born from the Xiao NRF52840 module and nurtured by the unwavering support of Seeed Studio, epitomizes the fusion of innovation and pragmatism. With BLE connectivity at its core, it elegantly bridges the gap between everyday objects and smart solutions. This creation underscores the potential of technology in its purest form. A sincere thank you to Seeed Studio for their pivotal role in turning this vision into a reality. As we stride confidently into the digital era, these innovations remind us that a humble button press can illuminate not just our path to belongings, but also a future that's brighter, smarter, and more connected than ever before.

Code

KeyFinder.ino

#include <ArduinoBLE.h>

BLEService KeyFinderService("19B10000-E8F2-537E-4F6C-D104768A1214");  // Bluetooth Low Energy KeyFinder Service

// Bluetooth Low Energy Key Finder Characteristic - custom 128-bit UUID, read and writable by central
BLEByteCharacteristic switchCharacteristic("19B10001-E8F2-537E-4F6C-D104768A1214", BLERead | BLEWrite);

const int ledPin = LED_BUILTIN;  // pin to use for the LED

void setup() {
  Serial.begin(115200);

  // set LED pin to output mode
  pinMode(ledPin, OUTPUT);
  pinMode(D6, OUTPUT);
  pinMode(D5, OUTPUT);
  pinMode(D7, INPUT);

  // begin initialization
  if (!BLE.begin()) {
    Serial.println("starting Bluetooth Low Energy module failed!");

    while (1);
  }

  // set advertised local name and service UUID:
  BLE.setLocalName("KeyFinder");
  BLE.setAdvertisedService(KeyFinderService);

  // add the characteristic to the service
  KeyFinderService.addCharacteristic(switchCharacteristic);

  // add service
  BLE.addService(KeyFinderService);

  // set the initial value for the characeristic:
  switchCharacteristic.writeValue(0);

  // start advertising
  BLE.advertise();

  Serial.println("BLE Key Finder Peripheral");
}

void loop() {
  // listen for Bluetooth Low Energy peripherals to connect:
  BLEDevice central = BLE.central();
  // if a central is connected to peripheral:
  if (central) {
    Serial.print("Connected to central: ");
    // print the central's MAC address:
    Serial.println(central.address());

    // while the central is still connected to peripheral:
    while (central.connected()) {
      if (switchCharacteristic.written()) {
        if (switchCharacteristic.value()) {
          Serial.println("LED on");
          digitalWrite(ledPin, LOW);  // changed from HIGH to LOW
          digitalWrite(D5, HIGH);
          while(1) {
            tone(D6, 500, 500);
            delay(1000);
            if(digitalRead(D7) == 0) {
              Serial.println(F("LED off"));
              digitalWrite(ledPin, HIGH);  // changed from LOW to HIGH
              digitalWrite(D5, LOW);
              digitalWrite(D6, LOW);
              break;
            }
          }
        }
      }
    }
    // when the central disconnects, print it out:
    Serial.print(F("Disconnected from central: "));
    Serial.println(central.address());
  }
}

Credits

Hamid Sheibani

2 projects • 4 followers

Experienced Embedded System Developer with a demonstrated history of working in the research industry.

Key Finder with the Xiao NRF52840 Module

Things used in this project

Hardware components

Software apps and online services

Story

Core Components and Purpose:

Crafting the Key Finder:

Operational Symphony:

Advantages and Real-world Scenarios:

Conclusion:

Schematics

KeyFinder

Code

KeyFinder.ino

Credits

Hamid Sheibani

Comments

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Key Finder with the Xiao NRF52840 Module

Key Finder with the Xiao NRF52840 Module

Things used in this project

Hardware components

Software apps and online services

Story

Core Components and Purpose:

Crafting the Key Finder:

Operational Symphony:

Advantages and Real-world Scenarios:

Conclusion:

Schematics

KeyFinder

Code

KeyFinder.ino

Credits

Hamid Sheibani

Comments

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