Bluetooth & BLE Patterns#

Bluetooth Low Energy dominates short-range embedded connectivity — phone-to-device communication, sensor beacons, asset tracking, and mesh networks all run over BLE. The “low energy” label is earned: a BLE peripheral advertising once per second draws roughly 10 µA average, three orders of magnitude less than an active WiFi radio. That efficiency comes from a protocol stack built around short, infrequent bursts of data rather than sustained connections.

This section covers BLE from the firmware engineer’s perspective: advertising and GAP roles, GATT service design, pairing and bonding security, connection parameter tuning for throughput or power, power optimization techniques measured with real hardware, and central-role scanning for gateway and aggregator applications.

Pages#

• BLE Advertising & GAP — Advertisement packets, scan responses, GAP roles, BLE 5.0 extended advertising, connectable vs non-connectable modes, and power at various advertising intervals.
• GATT Services & Characteristics — Services, characteristics, descriptors, handles, custom UUIDs, MTU negotiation, and profile design patterns across NimBLE, SoftDevice, and BlueZ.
• BLE Bonding & Security — Pairing vs bonding, security levels, LE Secure Connections, key storage, resolvable private addresses, and known BLE attacks.
• BLE Connection Parameters & Throughput — Connection interval, slave latency, supervision timeout, Data Length Extension, 2M PHY, and real-world throughput measurements.
• BLE Power Optimization — Advertising interval trade-offs, connection interval tuning for sensors, system-off modes, PPK2 measurement techniques, and BLE vs WiFi power comparison.
• BLE Central Role & Scanning — MCU as central: scan modes, UUID filtering, multi-connection management, gateway aggregation pattern, and scan window/interval tuning.