CBOR for constrained devices in IOT Protocols - Mini Project: Build & Apply

CBOR for Constrained Devices

📖 Scenario: You are working with small IoT devices that have limited memory and processing power. These devices need to send sensor data efficiently over the network. Using a compact data format like CBOR (Concise Binary Object Representation) helps reduce the size of the data sent.In this project, you will create a simple sensor data dictionary, configure a threshold value, encode the data to CBOR format, and then display the encoded result.

🎯 Goal: Build a small program that creates sensor data, sets a threshold, encodes the data using CBOR, and prints the encoded bytes. This simulates how constrained devices prepare data for efficient transmission.

📋 What You'll Learn

Create a dictionary called sensor_data with exact keys and values

Add a variable called threshold with a specific numeric value

Use the cbor2 library to encode the dictionary

Print the encoded CBOR bytes as output

💡 Why This Matters

🌍 Real World

IoT devices often have limited memory and bandwidth. Using CBOR helps send data efficiently, saving power and network usage.

💼 Career

Understanding CBOR encoding is useful for roles in IoT development, embedded systems, and network programming where data efficiency is critical.

1

Create sensor data dictionary

Create a dictionary called sensor_data with these exact entries: 'temperature': 22.5, 'humidity': 60, 'device_id': 'sensor_01'

IOT Protocols

# Create the sensor_data dictionary with temperature, humidity, and device_id
# Your code here

Hint

Use curly braces {} to create a dictionary with the exact keys and values.

2

Add threshold configuration

Add a variable called threshold and set it to the numeric value 25

IOT Protocols

sensor_data = {'temperature': 22.5, 'humidity': 60, 'device_id': 'sensor_01'}
# Add the threshold variable and set it to 25
# Your code here

Hint

Just create a variable named threshold and assign it the value 25.

3

Encode sensor data to CBOR

Import the cbor2 library and encode the sensor_data dictionary into a variable called encoded_data using cbor2.dumps(sensor_data)

IOT Protocols

sensor_data = {'temperature': 22.5, 'humidity': 60, 'device_id': 'sensor_01'}
threshold = 25
# Import cbor2 and encode sensor_data into encoded_data
# Your code here

Hint

Use import cbor2 at the top, then encode with cbor2.dumps().

4

Print the encoded CBOR data

Print the variable encoded_data to display the CBOR encoded bytes

IOT Protocols

import cbor2

sensor_data = {'temperature': 22.5, 'humidity': 60, 'device_id': 'sensor_01'}
threshold = 25
encoded_data = cbor2.dumps(sensor_data)
# Print the encoded_data variable
# Your code here

Hint

Use print(encoded_data) to show the encoded bytes.

Practice

1. What is the main advantage of using CBOR on constrained devices?

easy

A. It uses a compact binary format to save space and power

B. It requires a lot of memory to encode data

C. It only works with large servers

D. It converts data into plain text for readability

Solution

1. Step 1: Understand CBOR format purpose

   CBOR is designed to be a compact binary format, which means it uses less space than text formats.

2. Step 2: Relate to constrained devices needs

   Small devices have limited memory and power, so saving space and power is crucial.

3. Final Answer:

   It uses a compact binary format to save space and power -> Option A

4. Quick Check:

   Compact binary = saves space and power [OK]

Hint: CBOR is compact binary, perfect for small devices [OK]

Common Mistakes:

• Thinking CBOR uses more memory
• Assuming CBOR is text-based
• Believing CBOR only works on big servers

2. Which of the following is the correct way to represent an integer value 10 in CBOR hex notation?

easy

A. 0x0F

B. 0x1A

C. 0x18 0A

D. 0x0A

Solution

1. Step 1: Recall CBOR integer encoding

   Small integers 0-23 are encoded directly in the initial byte with major type 0.

2. Step 2: Check hex for integer 10

   Integer 10 fits in 0-23 range, so encoded as 0x0A (major type 0 + value 10).

3. Final Answer:

   0x0A -> Option D

4. Quick Check:

   Small int 10 = 0x0A [OK]

Hint: Small ints 0-23 encoded as single byte 0x00 to 0x17 [OK]

Common Mistakes:

• Using 0x1A which is for 32-bit integers
• Adding extra bytes unnecessarily
• Confusing hex values for different types

3. Given the CBOR byte sequence 0x83 0x01 0x02 0x03, what is the decoded data?

medium

A. [1, 2, 3]

B. {\"1\": 2, \"3\": 4}

C. [0x83, 0x01, 0x02, 0x03]

D. Error: invalid CBOR

Solution

1. Step 1: Interpret initial byte 0x83

   0x83 means array of length 3 (major type 4 + 3).

2. Step 2: Decode following bytes

   Next three bytes 0x01, 0x02, 0x03 are integers 1, 2, 3 respectively.

3. Final Answer:

   [1, 2, 3] -> Option A

4. Quick Check:

   0x83 = array(3), then 1,2,3 [OK]

Hint: 0x80+N means array of length N [OK]

Common Mistakes:

• Confusing array with map
• Reading bytes as hex literals
• Assuming syntax error without checking

4. You try to decode the CBOR data 0xA2 0x01 0x02 0x03 but get an error. What is the likely cause?

medium

A. 0x03 is not a valid CBOR byte

B. Integer keys must be strings in CBOR maps

C. Map length byte 0xA2 says 2 pairs but only 1 pair provided

D. CBOR does not support maps

Solution

1. Step 1: Analyze map length byte 0xA2

   0xA2 means a map with 2 key-value pairs expected.

2. Step 2: Count provided pairs

   Only bytes 0x01 and 0x02 provide one pair; 0x03 is extra byte, so incomplete data.

3. Final Answer:

   Map length byte 0xA2 says 2 pairs but only 1 pair provided -> Option C

4. Quick Check:

   Map length mismatch = error [OK]

Hint: Map length byte must match actual pairs [OK]

Common Mistakes:

• Thinking keys must be strings
• Assuming 0x03 is invalid byte
• Believing CBOR lacks map support

5. You want to encode a sensor reading with temperature 22 and humidity 55 as a CBOR map. Which byte sequence correctly encodes this data?

hard

A. 0xA2 0x01 0x16 0x02 0x37

B. 0xA2 0x6B 0x74 0x65 0x6D 0x70 0x65 0x72 0x61 0x74 0x75 0x72 0x65 0x16 0x68 0x68 0x75 0x6D 0x69 0x64 0x69 0x74 0x79 0x37

C. 0xA1 0x01 0x16 0x02 0x37

D. 0x82 0x16 0x37

Solution

1. Step 1: Understand CBOR map encoding

   0xA2 means a map with 2 key-value pairs.

2. Step 2: Check keys and values encoding

   Keys are text strings: "temperature" (length 11 = 0x6B) and "humidity" (length 8 = 0x68). Values 22 (0x16) and 55 (0x37) are small integers.

3. Step 3: Verify full byte sequence

   Sequence matches map with keys and values correctly encoded as text strings and integers.

4. Final Answer:

   0xA2 0x6B 0x74 0x65 0x6D 0x70 0x65 0x72 0x61 0x74 0x75 0x72 0x65 0x16 0x68 0x68 0x75 0x6D 0x69 0x64 0x69 0x74 0x79 0x37 -> Option B

5. Quick Check:

   Map with 2 text keys and int values = 0xA2 0x6B 0x74 0x65 0x6D 0x70 0x65 0x72 0x61 0x74 0x75 0x72 0x65 0x16 0x68 0x68 0x75 0x6D 0x69 0x64 0x69 0x74 0x79 0x37 [OK]

Hint: Map header 0xA2 + text keys + int values [OK]

Common Mistakes:

• Using array instead of map
• Encoding keys as integers
• Incorrect map length byte