BLE for wearables and beacons in IOT Protocols - Mini Project: Build & Apply

BLE for Wearables and Beacons

📖 Scenario: You are working on a simple IoT project to manage Bluetooth Low Energy (BLE) devices like wearables and beacons. These devices send small packets of data that you want to organize and analyze.Imagine you have a list of BLE devices with their IDs and signal strengths. You want to filter and display only the devices with a strong enough signal to connect reliably.

🎯 Goal: Build a small program that stores BLE device data, sets a signal strength threshold, filters devices based on this threshold, and then displays the filtered list.

📋 What You'll Learn

Create a dictionary with device IDs as keys and their signal strengths as values

Add a variable to set the minimum signal strength threshold

Use a dictionary comprehension to filter devices with signal strength above the threshold

Print the filtered dictionary showing only strong signal devices

💡 Why This Matters

🌍 Real World

BLE devices like wearables and beacons send small data packets with signal strength. Filtering helps decide which devices to connect to for better performance.

💼 Career

Understanding BLE data handling is useful for IoT developers, network engineers, and DevOps professionals managing device fleets.

1

Create BLE devices data

Create a dictionary called ble_devices with these exact entries: 'device_1': -70, 'device_2': -85, 'device_3': -60, 'device_4': -90

IOT Protocols

# Create the ble_devices dictionary with device IDs and signal strengths
# Your code here

Hint

Use curly braces to create a dictionary. Each device ID is a key, and its signal strength is the value.

2

Set signal strength threshold

Create a variable called signal_threshold and set it to -75 to represent the minimum signal strength to consider a device strong.

IOT Protocols

ble_devices = {'device_1': -70, 'device_2': -85, 'device_3': -60, 'device_4': -90}
# Set the signal_threshold variable to -75
# Your code here

Hint

Just assign the number -75 to the variable signal_threshold.

3

Filter devices with strong signals

Use a dictionary comprehension to create a new dictionary called strong_devices that includes only devices from ble_devices with signal strength greater than signal_threshold.

IOT Protocols

ble_devices = {'device_1': -70, 'device_2': -85, 'device_3': -60, 'device_4': -90}
signal_threshold = -75
# Create strong_devices dictionary using dictionary comprehension
# Your code here

Hint

Use the syntax: {key: value for key, value in dictionary.items() if condition}

4

Display strong BLE devices

Write a print statement to display the strong_devices dictionary.

IOT Protocols

ble_devices = {'device_1': -70, 'device_2': -85, 'device_3': -60, 'device_4': -90}
signal_threshold = -75
strong_devices = {device: strength for device, strength in ble_devices.items() if strength > signal_threshold}
# Print the strong_devices dictionary
# Your code here

Hint

Use print(strong_devices) to show the filtered devices.

Practice

1. What is the main advantage of using BLE (Bluetooth Low Energy) for wearables and beacons?

easy

A. It requires no pairing or security.

B. It provides very high data transfer speeds.

C. It uses very little power, extending battery life.

D. It works only with smartphones.

Solution

1. Step 1: Understand BLE's design goal

   BLE is designed to use minimal power to keep small devices running longer on batteries.

2. Step 2: Compare options

   High speed is not BLE's focus, pairing is often needed, and BLE works with many devices, not just smartphones.

3. Final Answer:

   It uses very little power, extending battery life. -> Option C

4. Quick Check:

   Low power = A [OK]

Hint: Remember BLE is for low power, not high speed [OK]

Common Mistakes:

• Confusing BLE with classic Bluetooth speed
• Thinking BLE needs no pairing always
• Assuming BLE only works with phones

2. Which of the following is the correct BLE advertising packet type used by beacons to broadcast data without connection?

easy

A. Connectable Directed Advertising

B. Extended Advertising

C. Scan Response Advertising

D. Non-Connectable Undirected Advertising

Solution

1. Step 1: Identify advertising types

   Beacons typically use Non-Connectable Undirected Advertising to broadcast data without needing a connection.

2. Step 2: Eliminate other options

   Connectable Directed requires connection, Scan Response is a reply to scans, Extended Advertising is newer but not typical for simple beacons.

3. Final Answer:

   Non-Connectable Undirected Advertising -> Option D

4. Quick Check:

   Beacon broadcasts = Non-Connectable Undirected [OK]

Hint: Beacons broadcast without connection using non-connectable packets [OK]

Common Mistakes:

• Choosing connectable advertising for beacons
• Confusing scan response with advertising
• Assuming extended advertising is always used

3. Given this Python snippet using a BLE library to scan for devices, what will be printed if a beacon advertising with name 'Beacon123' is found?

devices = scanner.scan(5)
for dev in devices:
    if dev.getValueText(9) == 'Beacon123':
        print(f"Found: {dev.addr}")

medium

A. Found:

B. Found: Beacon123

C. Error: getValueText is not a function

D. No output

Solution

1. Step 1: Understand the code logic

   The code scans for 5 seconds, then checks each device's advertised name (type 9) for 'Beacon123'.

2. Step 2: Analyze the print statement

   If found, it prints 'Found: ' plus the device's address, not the name itself.

3. Final Answer:

   Found: <device address> -> Option A

4. Quick Check:

   Print device address when name matches [OK]

Hint: Check what is printed: address, not name [OK]

Common Mistakes:

• Expecting the name printed instead of address
• Thinking getValueText is invalid
• Assuming no output if beacon found

4. You try to connect to a wearable device using its BLE address but get a connection timeout error. Which of these is the most likely cause?

medium

A. The device is advertising as non-connectable only.

B. The device address is invalid format.

C. The scanning duration was too long.

D. The device uses classic Bluetooth, not BLE.

Solution

1. Step 1: Understand connection timeout causes

   If a device advertises as non-connectable, it will not accept connection requests, causing timeout.

2. Step 2: Evaluate other options

   Invalid address would cause immediate error, scanning duration doesn't affect connection, classic Bluetooth devices won't appear in BLE scan.

3. Final Answer:

   The device is advertising as non-connectable only. -> Option A

4. Quick Check:

   Non-connectable device causes timeout [OK]

Hint: Non-connectable advertising means no connections allowed [OK]

Common Mistakes:

• Confusing scanning time with connection issues
• Assuming invalid address causes timeout instead of error
• Mixing classic Bluetooth with BLE scanning

5. You want to read the heart rate data from a wearable using BLE. Which sequence of steps correctly describes the process?

hard

A. Discover GATT services -> Scan for devices -> Connect to device -> Read heart rate characteristic -> Disconnect

B. Scan for devices -> Connect to device -> Discover GATT services -> Read heart rate characteristic using UUID -> Disconnect

C. Connect to device -> Scan for devices -> Read heart rate characteristic -> Discover GATT services -> Disconnect

D. Read heart rate characteristic -> Scan for devices -> Connect to device -> Discover GATT services -> Disconnect

Solution

1. Step 1: Understand BLE data reading workflow

   First, scan to find the device, then connect to it to access its data.

2. Step 2: Discover GATT services and read characteristic

   After connecting, discover services to find the heart rate characteristic by UUID, then read it.

3. Step 3: Disconnect after reading

   Once data is read, disconnect to save power and free resources.

4. Final Answer:

   Scan for devices -> Connect to device -> Discover GATT services -> Read heart rate characteristic using UUID -> Disconnect -> Option B

5. Quick Check:

   Scan -> Connect -> Discover -> Read -> Disconnect [OK]

Hint: Follow BLE steps in order: scan, connect, discover, read, disconnect [OK]

Common Mistakes:

• Trying to read before connecting
• Discovering services before connecting
• Skipping disconnect step