1641  Appendix

NoteKey Takeaway

In one sentence: This appendix is your quick-reference companion for IoT terminology, protocol comparisons, sensor specifications, and essential engineering formulas.

Remember this rule: Use this appendix to refresh your memory during design decisions or study sessions, but return to the detailed chapters for deeper explanations and context.

1641.1 Learning Objectives

By using this appendix, you will be able to:

  • Look up IoT terminology: Find definitions for acronyms and technical terms used throughout the book
  • Compare protocols: Use reference tables to evaluate different IoT technologies
  • Reference sensor specifications: Access common sensor parameters for design decisions
  • Apply engineering formulas: Use networking, electronics, and battery life calculations
  • Find standards references: Access links to IEEE, IETF, and industry specifications

1641.2 A. Glossary of IoT Terms

Term Definition
6LoWPAN IPv6 over Low-Power Wireless Personal Area Networks - Adaptation layer enabling IPv6 on IEEE 802.15.4 networks
ADC Analog-to-Digital Converter - Hardware that converts continuous analog signals to discrete digital values
AMQP Advanced Message Queuing Protocol - Message-oriented middleware protocol for reliable messaging
BLE Bluetooth Low Energy - Low-power variant of Bluetooth designed for IoT applications
CoAP Constrained Application Protocol - Lightweight protocol for resource-constrained IoT devices
DTLS Datagram Transport Layer Security - Security protocol for UDP-based communications
Edge Computing Processing data near the source rather than in a centralized cloud
Fog Computing Distributed computing layer between edge devices and cloud
Gateway Device that bridges different network protocols or technologies
GPIO General Purpose Input/Output - Configurable pins on microcontrollers
I²C Inter-Integrated Circuit - Two-wire serial communication protocol
IoT Internet of Things - Network of physical devices connected to the internet
LoRa Long Range - Spread spectrum modulation technique for LPWAN
LoRaWAN LoRa Wide Area Network - MAC layer protocol built on LoRa
LPWAN Low-Power Wide-Area Network - Network designed for long range, low power IoT
M2M Machine-to-Machine - Direct communication between devices
MAC Media Access Control - Protocol layer managing access to shared medium
MCU Microcontroller Unit - Integrated circuit containing processor, memory, and I/O
MQTT Message Queuing Telemetry Transport - Lightweight publish/subscribe protocol
NB-IoT Narrowband IoT - Cellular LPWAN technology using licensed spectrum
NFC Near Field Communication - Short-range wireless technology (~10cm)
OTA Over-The-Air - Wireless delivery of updates or configuration
PHY Physical Layer - Lowest layer of the OSI model handling raw bit transmission
PWM Pulse Width Modulation - Technique for controlling power to devices
QoS Quality of Service - Mechanism for prioritizing network traffic
REST Representational State Transfer - Architectural style for web services
RFID Radio-Frequency Identification - Wireless identification using radio waves
RPL Routing Protocol for Low-Power and Lossy Networks
RSSI Received Signal Strength Indicator - Measure of signal power
RTT Round-Trip Time - Time for a signal to travel to destination and back
SDN Software-Defined Networking - Network architecture with centralized control
Sigfox Proprietary LPWAN technology using ultra-narrow band
SPI Serial Peripheral Interface - Synchronous serial communication protocol
TLS Transport Layer Security - Cryptographic protocol for secure communication
UART Universal Asynchronous Receiver/Transmitter - Serial communication hardware
UDP User Datagram Protocol - Connectionless transport protocol
WSN Wireless Sensor Network - Network of distributed sensor nodes
Zigbee IEEE 802.15.4-based specification for low-power mesh networks
Z-Wave Proprietary wireless protocol for home automation

1641.3 B. Protocol Comparison Tables

1641.3.1 Short-Range Wireless Protocols

Protocol Range Data Rate Power Topology Use Cases
Wi-Fi 50-100m 1-1000+ Mbps High Star High-bandwidth applications
Bluetooth 10-100m 1-3 Mbps Medium Point-to-point Audio, data transfer
BLE 10-100m 1-2 Mbps Low Star, Mesh Wearables, beacons
Zigbee 10-100m 250 kbps Very Low Mesh Home automation
Z-Wave 30-100m 100 kbps Very Low Mesh Home automation
Thread 10-30m 250 kbps Very Low Mesh Smart home
NFC <10cm 424 kbps Very Low Point-to-point Payments, access

1641.3.2 LPWAN Technologies

Technology Range Data Rate Spectrum Topology Battery Life
LoRaWAN 2-15 km 0.3-50 kbps Unlicensed Star 10+ years
Sigfox 10-50 km 100-600 bps Unlicensed Star 10+ years
NB-IoT 1-10 km 20-250 kbps Licensed Star 10+ years
LTE-M 1-10 km 1 Mbps Licensed Star 10+ years
Weightless 5-10 km 0.1-10 Mbps Varies Star 10+ years

1641.3.3 Application Layer Protocols

Protocol Transport Message Pattern QoS Overhead Best For
MQTT TCP Pub/Sub 0,1,2 Low Real-time telemetry
CoAP UDP Request/Response Confirmable Very Low Constrained devices
HTTP/REST TCP Request/Response N/A High Web integration
AMQP TCP Queue-based Yes Medium Enterprise messaging
XMPP TCP Pub/Sub N/A High Presence, messaging

1641.4 C. Common Sensor Specifications

1641.4.1 Temperature Sensors

Sensor Range Accuracy Interface Power
DHT22 -40 to 80°C ±0.5°C Digital 1.5mA
DS18B20 -55 to 125°C ±0.5°C 1-Wire 1.5mA
BME280 -40 to 85°C ±1°C I²C/SPI 3.6µA
LM35 -55 to 150°C ±0.5°C Analog 60µA
TMP117 -55 to 150°C ±0.1°C I²C 3.5µA

1641.4.2 Motion/Orientation Sensors

Sensor Type Range Interface Features
MPU6050 6-axis IMU ±16g, ±2000°/s I²C Gyro + Accel
MPU9250 9-axis IMU ±16g, ±2000°/s I²C/SPI + Magnetometer
ADXL345 Accelerometer ±16g I²C/SPI Low power
HC-SR501 PIR Motion 3-7m Digital Adjustable

1641.4.3 Distance/Proximity Sensors

Sensor Technology Range Accuracy Interface
HC-SR04 Ultrasonic 2-400cm ±3mm GPIO
VL53L0X ToF Laser 0-200cm ±3% I²C
Sharp GP2Y0A21 IR 10-80cm ±5% Analog

1641.5 D. ESP32 Pin Reference

1641.5.1 GPIO Capabilities

GPIO Input Output ADC DAC Touch Notes
0 ✓ ✓ ✓ - ✓ Boot mode (pull-up)
1 - ✓ - - - TX0
2 ✓ ✓ ✓ - ✓ On-board LED
3 ✓ - - - - RX0
4 ✓ ✓ ✓ - ✓ General purpose
5 ✓ ✓ - - - VSPI CS
12-15 ✓ ✓ ✓ - ✓ HSPI
16-17 ✓ ✓ - - - UART2
18-19 ✓ ✓ - - - VSPI
21-22 ✓ ✓ - - - I²C
23 ✓ ✓ - - - VSPI MOSI
25-26 ✓ ✓ ✓ ✓ - DAC capable
27 ✓ ✓ ✓ - ✓ General purpose
32-39 ✓ * ✓ - * ADC1 (34-39 input only)

1641.5.2 Common Pin Assignments

Default I²C:  SDA = GPIO 21, SCL = GPIO 22
Default SPI:  MOSI = GPIO 23, MISO = GPIO 19, SCK = GPIO 18, CS = GPIO 5
UART0:        TX = GPIO 1, RX = GPIO 3 (USB Serial)
UART2:        TX = GPIO 17, RX = GPIO 16

1641.6 E. Unit Conversions

1641.6.1 Data Rate

Unit Equivalent
1 bps 1 bit/second
1 kbps 1,000 bps
1 Mbps 1,000,000 bps
1 Gbps 1,000,000,000 bps
1 Byte/s 8 bps

1641.6.2 Signal Strength (dBm)

dBm mW Typical Use
30 1000 Max Wi-Fi (US)
20 100 Typical router
10 10 -
0 1 -
-10 0.1 Good Wi-Fi signal
-50 0.00001 Excellent Wi-Fi
-70 0.0000001 Good Wi-Fi
-90 0.000000001 Weak Wi-Fi
-120 - LoRa sensitivity

1641.6.3 Power Consumption

Current @ 3.3V Battery Life (2000mAh)
1 mA 3.3 mW 83 days
100 µA 330 µW 833 days (2.3 years)
10 µA 33 µW 22.8 years
1 µA 3.3 µW 228 years

1641.7 F. Useful Formulas

1641.7.1 Networking

Free Space Path Loss (dB): \[FSPL = 20 \log_{10}(d) + 20 \log_{10}(f) + 20 \log_{10}\left(\frac{4\pi}{c}\right)\]

Link Budget: \[P_{rx} = P_{tx} + G_{tx} + G_{rx} - L_{path} - L_{other}\]

Shannon Capacity: \[C = B \log_2(1 + SNR)\]

1641.7.2 Electronics

Ohm’s Law: \[V = I \times R\]

Power: \[P = V \times I = I^2 \times R = \frac{V^2}{R}\]

Voltage Divider: \[V_{out} = V_{in} \times \frac{R_2}{R_1 + R_2}\]

RC Time Constant: \[\tau = R \times C\]

Cutoff Frequency (RC Filter): \[f_c = \frac{1}{2\pi RC}\]

1641.7.3 Battery Life

Battery Life (hours): \[Life = \frac{Battery_{mAh}}{I_{average_{mA}}}\]

Duty Cycle Average Current: \[I_{avg} = (I_{active} \times D) + (I_{sleep} \times (1-D))\]

Where D = duty cycle (0-1)

1641.8 G. References and Further Reading

TipMVU: IoT Standards Landscape

Core Concept: IoT standards come from different organizations - IEEE for physical/MAC layers (802.11, 802.15.4), IETF for internet protocols (CoAP, 6LoWPAN, RPL), and industry alliances for application-specific specs (LoRaWAN, Zigbee, Matter).

Why It Matters: Knowing which organization owns a standard tells you where to find official documentation, certification requirements, and future roadmaps for the technology you are using.

Key Takeaway: When researching a protocol, start with the standards body that owns it - IEEE for wireless PHY/MAC, IETF for IP-based protocols, and alliance websites for ecosystem-specific features.

1641.8.1 Standards Organizations

1641.8.2 Key RFCs and Standards

Document Title
RFC 7252 CoAP - Constrained Application Protocol
RFC 6550 RPL - Routing Protocol for LLNs
RFC 4944 IPv6 over 802.15.4 (6LoWPAN)
RFC 6282 6LoWPAN Header Compression
IEEE 802.15.4 Low-Rate Wireless PANs
IEEE 802.11 Wireless LAN (Wi-Fi)

1641.10 Summary

This appendix serves as a quick reference companion to the main textbook:

  • Glossary: 45+ IoT terms with concise definitions
  • Protocol Comparisons: Side-by-side tables for wireless, LPWAN, and application protocols
  • Sensor Specifications: Common temperature, motion, and distance sensors with specs
  • ESP32 Pin Reference: GPIO capabilities and common pin assignments
  • Engineering Formulas: Essential calculations for link budgets, battery life, and electronics

1641.11 Knowledge Check

  1. Which standards body is most directly associated with IEEE 802.11 (Wi-Fi) and IEEE 802.15.4?

IEEE publishes the 802 family of networking standards, including 802.11 (Wi-Fi) and 802.15.4 (LR-WPAN used by Zigbee/Thread).

  1. RFC 7252 specifies which IoT application protocol?

RFC 7252 defines CoAP, a lightweight REST-like application protocol designed for constrained devices and networks.

  1. If you need a quick comparison of wireless and application protocols while making design decisions, this appendix is best used as:

The appendix is meant to accelerate recall with tables, glossaries, and formulas; the main chapters provide deeper explanations and context.

  1. RFCs for protocols like CoAP, RPL, and 6LoWPAN are published by:

The IETF publishes RFCs (Request for Comments) for many internet protocols, including key IoT-related specifications like CoAP and RPL.

1641.12 What’s Next

Use this appendix as a reference while studying:

  • Return to specific chapters for detailed explanations of concepts
  • Use the Quiz Navigator to test your understanding
  • Try the Simulation Playground to apply these concepts hands-on