Handbook
IoT communication protocols (blueprint)
Purpose: Protocol selection guidance and implementation considerations for IoT device communication. Each protocol entry covers its architecture, message format, QoS, security, power profile, and best-fit scenarios.
Why protocol selection matters: The application protocol (and its transport) constrains latency, duty cycle, security posture, NAT behavior, and operational cost. Committing late often forces gateways, duplicate stacks, or non-interoperable silos. Treat protocol choice as an architecture decision tied to power budgets, update strategy, and cloud or on-prem integrations — see Embedded / IoT engineering body of knowledge for the embedded/IoT map and Embedded / IoT ↔ SDLC ↔ PDLC bridge for lifecycle impact.
Audience: Teams adopting Embedded / IoT Engineering; project-specific protocol configuration stays in docs/development/embedded/protocols/.
Protocol stack (reference layers)
| Protocol | Layer | Focus | Deep dive |
|---|---|---|---|
| MQTT & CoAP | Application | Pub/sub vs REST-like constrained apps — QoS, observe, brokers | MQTT & CoAP: Application-Layer IoT Protocols |
| BLE & Zigbee | Link + network / app | GATT, mesh, Thread/Matter context, coexistence | BLE, Zigbee & Short-Range Wireless Protocols |
| LoRaWAN | Network | LPWAN — spreading factors, ADR, class A/B/C, join procedures, fair-use policy | EMBEDDED-IOT.md §3 |
| Modbus | Application (Serial/TCP) | Industrial — RTU vs TCP, function codes, register mapping, polling vs event | EMBEDDED-IOT.md §3 |
| OPC UA | Application (TCP) | Industrial interoperability — information model, security, pub/sub, companion specifications | EMBEDDED-IOT.md §3 |
| CAN bus | Data link | Automotive/industrial — message arbitration, error handling, CANopen, J1939 | EMBEDDED-IOT.md §3 |
| Matter | Application | Smart home — Thread/Wi-Fi transport, device types, commissioning, multi-admin | (see BLE, Zigbee & Short-Range Wireless Protocols) |
Core knowledge: Embedded / IoT engineering body of knowledge — communication protocol overview and selection criteria.
Bridge: Embedded / IoT ↔ SDLC ↔ PDLC bridge — protocol choices across the lifecycle.
Keep project-specific safety documentation in docs/safety/ and hazard analyses in docs/security/, not in this file.