Bluetooth Low Energy ( BLE ) is a low-data-rate, short-range wireless communication protocol developed by the Bluetooth Special Interest Group (SIG) . It operates in the 2.4GHz band and significantly reduces power consumption primarily through a simplified protocol, intermittent transmission and reception, and sleep mechanisms.
It supports various topologies, including point-to-point, broadcast, and Bluetooth Mesh networking. It also supports CRC error detection, FEC forward error correction mechanisms, and multiple physical layer PHYs (1M/2M/S2/S8), effectively balancing communication reliability and transmission distance. It is suitable for wireless communication scenarios with low data volume and long battery life, such as wearable devices, smart homes, IoT sensors, and large-scale device networking.
Classic Bluetooth (BR/EDR) and Bluetooth Low Energy (BLE) Image source: SIG
According to data from renowned industry research firm ABI Research, global Bluetooth device shipments are projected to reach nearly 6 billion units in 2026 and exceed 8 billion units in 2030, maintaining a high growth rate.
Among the three types of devices—Classic Bluetooth (BR/EDR), Bluetooth Low Energy (BLE), and Dual-mode Bluetooth—BLE devices, with their ultra-low power consumption and flexible adaptability, are continuously penetrating into fields such as electronic shelf labels (ESL), asset tracking tags, smart tags, health monitoring devices, and smart home systems, making them the core driver of global Bluetooth market growth in the coming years.
Bluetooth Classic (BR/EDR, Bluetooth Base Rate/Enhanced Data Rate) is a low-power radio frequency communication technology that primarily operates in the unlicensed 2.4 GHz ISM band and transmits data streams through 79 channels on the band. Bluetooth Classic supports point-to-point device communication and is mainly used for wireless audio streaming.
It has become the standard radio protocol for driving wireless speakers, headphones, and in-vehicle entertainment systems. In addition, Bluetooth Classic also supports data transmission applications, with mobile printing being a typical example.
Bluetooth Low Energy (BLE) is designed for extremely low power operation. It also operates in the unlicensed 2.4 GHz ISM band and transmits data via 40 channels (3 broadcast channels and 37 data channels).
Besides its widespread use in short-range wireless communication scenarios requiring small data volumes and long battery life , BLE also holds significant potential in high-precision location services. Currently, BLE possesses distance sensing capabilities, enabling one device to detect the presence of another, calculate distance, and determine orientation.
The Bluetooth Low Energy (BLE) protocol stack consists of many layers and functional modules, some of which are mandatory and some are optional. Its overall architecture is divided into two core parts from top to bottom: the host and the controller.
The two can define communication interaction specifications and data packet formats in a unified manner through the standardized HCI host controller interface, so as to achieve decoupling and interoperability between the underlying radio frequency physical link and the upper protocol stack and application layer.
BLE protocol stack diagram source: SIG
The controller is the lowest level part of the protocol stack that interacts directly with the radio frequency hardware. It is responsible for all radio frequency-related functions at the physical and link layers, including radio signal transmission and reception, modulation and demodulation, timing control, frequency hopping management, link maintenance, and data packet encoding and decoding. Its core function is to establish and maintain a reliable wireless physical connection, providing a stable radio frequency link foundation for upper-layer protocols.
The host is a higher-level logic module in the protocol stack, running in the MCU or application processor. It includes protocol layers such as L2CAP, ATT, GATT, GAP, and various profiles. It is responsible for defining data formats, device roles, security policies, and application interaction logic, enabling business data interaction and application scenario adaptation between devices.
LC3 (Low Complexity Communication Codec) is a dedicated audio compression algorithm that is mandatory to support in the Bluetooth LE Audio (Bluetooth Low Energy Audio) standard. It is responsible for efficiently compressing the raw PCM audio data into data packets suitable for BLE link transmission at the transmitting end, and decompressing and restoring it to PCM audio at the receiving end.
The BLE link layer defines two types of data packet formats for different physical layers (PHY): uncoded PHY data packets (compatible with LE 1M and LE 2M physical layers) and coded PHY data packets (new in BLE 5.0, compatible with Coded PHY long-distance mode). These two formats correspond to different application scenarios.
Image source: SIG
Among them, the uncoded PHY data packet is the most basic link layer frame format of BLE, designed specifically for the LE 1M and LE 2M physical layers. It has a simplified and efficient structure and mainly includes fields such as preamble, access address, PDU, and CRC.
The preamble is used for clock synchronization, the access address is used for link identification, the PDU carries valid data, and the CRC ensures transmission reliability. It has a high overall transmission rate and low latency, making it suitable for short-distance, low-interference scenarios. It is a common choice for conventional consumer-grade BLE devices (wristbands, mice, short-range sensors, etc.).
Low-power encoded PHY data packets are a new dedicated frame format added in BLE 5.0, optimized for long-distance and high-interference scenarios. It uses the FEC forward error correction mechanism to divide the data into two error-correcting blocks for transmission, supports two encoding modes: S=2 and S=8, and adds encoding indicator CI and error-correcting block end markers TERM1/TERM2.
Although the transmission rate is reduced, the anti-interference capability and communication distance are greatly improved, making it suitable for low -speed transmission scenarios with high requirements for connection stability, such as industrial sensing, smart homes, and outdoor asset positioning.
It is worth mentioning that the implementation of any communication protocol and its solution requires a mature and reliable hardware module as support, and BLE chips/modules are the core carriers that connect technical concepts and application scenarios.
For example, Huapu Micro's independently developed CMT4531W is a high-performance BLE SoC chip. It has an embedded high-performance, low-power 32-bit processor, 48KB SRAM, 256KB FLASH, and an advanced BLE5.2 RF transceiver. It supports AOA (Angle of Arrival) and AOD (Angle of Departure), RSSI (Receiver Signal Strength Indication), and master-slave roles.
At the same time, the chip also has rich serial peripheral interfaces and integrated application IP design, which can help developers quickly build end products with lower bill of materials (BOM) costs.
In terms of power consumption, the CMT4531W has a receive current as low as 3.8mA and a transmit current of only 4.2mA@3.3V, and supports four low-power modes. In Sleep mode, the current is as low as 1.4μA with all 48KB RAM held, and in PD mode, the power consumption can be reduced to 130nA.
In terms of wireless performance and system integration, the CMT4531W integrates a BLE 5.2 compliant RF transceiver with a maximum transmit power of +6 dBm, enabling stable signal transmission in complex environments.
Meanwhile, the CMT4531W also supports multiple connections, extended data packet length, KEYSCAN, IRC, a 10-bit 1.33Msps ADC (configurable to 16-bit 16Ksps), analog MIC input, PGA amplification, and can independently complete the functions of device management, data interaction, status monitoring and OTA upgrade of the vehicle OBU, effectively simplifying the hardware architecture and reducing the PCB size.
The HM-BT2401DA is a channel sounding module based on a high-performance BLE6.0 chip, capable of centimeter-level ranging and positioning. It supports two ranging roles: initiator (which wants to calculate the distance from itself to the target device) and reflector (which responds to the initiator). It supports dual-antenna paths and can quickly achieve wireless connection and ranging between the initiator and reflector via AT commands. It has low external MCU resource consumption and a simple development process.
The HM-BT2401DA supports both RTT (Round-Trip Time) and PBR (Phase-Based Ranging) modes. During channel probing, the initiator transmits carrier signals or data packets in 72 designated 2.4 GHz physical channels, while the reflector responds by sending carrier signals or data packets back to the initiator.
After obtaining the round-trip time of the data packets and the phase difference data between carrier signals of different frequencies, the initiator runs a specific distance measurement algorithm to determine the accurate distance between the two and reports the calculation results to the MCU via serial port.
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