BLE — Bluetooth Low Energy
Bluetooth Low Energy (BLE), also known as Bluetooth Smart, is a wireless communication protocol designed for ultra-low-power devices that transmit small amounts of data over short to medium distances. Unlike classic Bluetooth (used for audio streaming), BLE is optimized for IoT sensors, wearables, beacons, and industrial monitoring where battery life — not bandwidth — is the primary constraint.
BLE 5.4 — Current Specification (2023)
The latest Bluetooth 5.4 specification, released by the Bluetooth SIG in February 2023, introduces key features for large-scale IoT deployments:
| Feature | What It Does | Use Case |
|---|---|---|
| PAwR (Periodic Advertising with Response) | Bidirectional connectionless communication with thousands of devices | Electronic Shelf Labels — one gateway, 32,640 devices |
| Encrypted Advertising Data (EAD) | Encrypted broadcast data without establishing a connection | Secure beacons, asset tracking |
| LE GATT Security Levels | Devices communicate required security level before connection | Streamlined pairing for medical devices |
| Advertising Coding Selection | Host selects long-range coding scheme | Extended range optimization |
BLE Technical Specifications
| Parameter | Value |
|---|---|
| Frequency band | 2.4 GHz ISM (2400–2483.5 MHz) |
| Channels | 40 (3 advertising + 37 data) |
| Data rate | 1 Mbps (LE 1M) / 2 Mbps (LE 2M) / 125–500 kbps (LE Coded) |
| Range | 10–100 m typical, up to 240 m (BLE 5.x), 1+ km with LE Coded PHY |
| TX power | -20 dBm to +20 dBm |
| Peak current | 5–15 mA (transmit), <1 µA (sleep) |
| Topology | Point-to-point, broadcast, mesh (Bluetooth Mesh) |
| Security | AES-128-CCM encryption, LE Secure Connections (ECDH P-256) |
BLE vs. Other IoT Protocols
| Protocol | Range | Power | Data Rate | Best For |
|---|---|---|---|---|
| BLE 5.4 | 10–240 m | Ultra-low | 1–2 Mbps | Wearables, sensors, beacons |
| LoRaWAN | 5–15 km | Ultra-low | 0.3–50 kbps | Remote sensors, agriculture |
| Wi-Fi 6 | 50–100 m | Medium-high | 100+ Mbps | Cameras, gateways |
| Thread/Matter | Mesh (300 m) | Low | 250 kbps | Smart home, building automation |
| LTE-M / NB-IoT | Cellular | Medium | 1 Mbps / 250 kbps | Asset tracking, metering |
BLE in Hardware Design
When designing BLE devices, key considerations include:
- Antenna design — PCB trace antenna vs. chip antenna vs. external — each affects range, cost, and enclosure constraints
- Crystal accuracy — BLE requires ±50 ppm; cheaper crystals cause connection failures
- RF matching network — Impedance matching is critical for TX efficiency and range
- Coexistence — 2.4 GHz is crowded (Wi-Fi, Zigbee, microwave ovens); proper channel hopping and adaptive frequency hopping (AFH) are essential
- Regulatory — CE marking (RED Directive) and FCC Part 15 certification required for market access
Key BLE SoC Platforms
| Vendor | Chip | BLE Version | Extra Features |
|---|---|---|---|
| Nordic Semiconductor | nRF52840, nRF5340 | 5.3 / 5.4 | Thread, Zigbee, Direction Finding |
| Espressif | ESP32-C6, ESP32-H2 | 5.0 / 5.3 | Wi-Fi 6, Thread, Matter |
| STMicroelectronics | STM32WB55 | 5.4 | Dual-core (M4 + M0), Zigbee |
| Silicon Labs | EFR32BG24 | 5.4 | AI/ML accelerator, PSA L3 security |
| TI | CC2340 | 5.4 | Ultra-low-power, SimpleLink SDK |
Related Terms
- IoT — BLE is the most widely deployed IoT connectivity protocol for short-range applications.
- Secure Element — Hardware-backed key storage for BLE device identity and pairing credentials.
- Matter — The smart home standard that can operate over BLE for device commissioning.
We design BLE-based products using Nordic nRF and ESP32 platforms — from antenna design to certified production firmware. See our Embedded Systems Development services.