54  Data Formats for IoT

54.1 Overview

Data formats determine how IoT devices encode and exchange information. The choice of format impacts bandwidth usage, battery life, parsing speed, and development complexity. This series covers everything from human-readable JSON to ultra-compact custom binary encodings.

NoteKey Takeaway

In one sentence: Choose your data format based on bandwidth constraints and debugging needs - JSON for prototyping and high-bandwidth networks, CBOR for most IoT deployments, and custom binary only when every byte matters.

Remember this rule: CBOR gives you 80% of custom binaryโ€™s efficiency with 20% of the engineering effort - itโ€™s the sweet spot for most constrained IoT applications.

54.2 Chapter Guide

This topic has been organized into four focused chapters:

54.2.1 1. IoT Data Formats Overview

Difficulty: Foundational | Time: ~20 minutes

Start here to understand why data formats matter. Covers:

  • Why format choice impacts bandwidth, battery, and development
  • JSON as the universal default
  • The format spectrum from human-readable to binary
  • Real-world size comparisons (62-byte JSON vs 17-byte custom binary)
  • Common misconceptions about JSON in IoT

Best for: Beginners, anyone starting a new IoT project

54.2.2 2. Binary Data Formats

Difficulty: Intermediate | Time: ~25 minutes

Deep dive into efficient binary encodings. Covers:

  • CBOR: Binary JSON with 47% size reduction
  • Protocol Buffers: Schema-based with 77% reduction
  • Custom Binary: Maximum efficiency patterns
  • Type systems, encoding details, and performance benchmarks
  • Library recommendations by platform

Best for: Developers implementing bandwidth-constrained systems

54.2.3 3. Data Format Selection

Difficulty: Intermediate | Time: ~20 minutes

Decision frameworks for choosing the right format. Covers:

  • Step-by-step decision tree
  • Real-world application mapping (12 use cases)
  • Detailed cost analysis scenario (soil moisture network)
  • Fleet tracking quiz with calculations
  • Total cost of ownership considerations

Best for: Technical leads, architects making format decisions

54.2.4 4. Data Formats Practice

Difficulty: Intermediate | Time: ~30 minutes

Hands-on scenarios and assessments. Covers:

  • Smart meter deployment scenario (10,000 devices)
  • Agricultural sensor design (LoRaWAN constraints)
  • Format migration strategy (50,000 deployed sensors)
  • Industrial monitoring (two-tier format strategy)
  • Worked example: LoRaWAN payload design with battery calculations
  • Knowledge check questions

Best for: Students preparing for assessments, practitioners validating knowledge

54.3 Quick Reference

Format Typical Size Best For
JSON 95 bytes Wi-Fi, prototyping, debugging
CBOR 50 bytes LoRaWAN, NB-IoT, CoAP
Protobuf 22 bytes High-volume, gRPC, stable schemas
Custom Binary 16 bytes Sigfox, ultra-low-power, extreme constraints

54.4 Prerequisites

Before starting this series, you should be familiar with: