Bluetooth Low Energy (BLE), launched in 2010, ushered in a new era of connectivity, particularly between smart devices and smartphones. BLE is a new wireless protocol that shares some functionalities with traditional Bluetooth. While BLE incorporates many of the same concepts as Bluetooth, such as simple connections and fast data transmission, it has been simplified to achieve low power consumption, reliability, and quick data transfer between devices.
This article introduces the basic knowledge of BLE that you need to understand when developing or designing Bluetooth module products. Before diving into BLE, it’s important to note its naming: Bluetooth Smart was the initial marketing name for Bluetooth Low Energy. However, the name and logo never gained popularity—most people, including ourselves, simply refer to it as Bluetooth Low Energy or BLE. From a marketing perspective, this can be confusing—after all, is there such a thing as non-smart Bluetooth? Even more confusing is the existence of devices, often referred to as “dual-mode” or “Bluetooth Smart Ready,” which support both Bluetooth Low Energy and Bluetooth Classic (such as those used for making calls on smartphones). While it’s commonly called BLE, the Bluetooth SIG (Special Interest Group) discourages the use of this term, as BLE is not their trademark. Therefore, the official term is Bluetooth LE.
The Bluetooth protocol is one of the most common wireless communication protocols and has been used in smartphones, computers, and other devices for over a decade. Most of us are familiar with Bluetooth and how it connects headphones or allows us to make phone calls. However, the explosive growth of Bluetooth devices and new use cases made the Bluetooth SIG and other companies realize that Bluetooth consumed too much power and took too long to connect in some IoT applications. For example, a Bluetooth keychain tracker might not last long on battery power, and the connection time could be quite lengthy, which is frustrating for users.
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Comparison of ZigBee vs Bluetooth Mesh
Starting with the iPhone 4S, Apple began supporting BLE in its devices, opening the door for many small battery-powered devices. Before the advent of BLE, traditional Bluetooth could be cumbersome for users and developers. Traditional Bluetooth was complex, power-hungry, and required authentication chips on iPhones, which made these products expensive. For data transmission, Apple devices could support BLE without such requirements, lowering costs. One of BLE’s strongest features is its scalability and how it enables any developer with an idea to exchange information, unlike the rigid structure of traditional Bluetooth.
Wireless Protocol Comparison
Bluetooth and BLE are excellent protocols for simplifying product connections. However, it’s important to understand their position compared to other wireless technologies. Wi-Fi, Zigbee, and other protocols outperform BLE in certain applications, and BLE modules may not be suitable for all IoT scenarios. Let’s take a look at some of the differences between the BLE protocol, Zigbee, and Wi-Fi protocols:
Bluetooth Low Energy
Zigbee modules, Wi-Fi modules, and BLE Bluetooth modules all use the 2.4GHz ISM frequency band, but their functions differ significantly. While BLE operates over a short range and consumes less power than Zigbee and Wi-Fi modules, it has evolved in the Bluetooth 5.0 specification to allow up to 20dBm output power and BLE long-range functionality. This means BLE can cover a wide range, with actual distances exceeding 1 km. When selecting batteries, the lower peak current consumption of BLE is crucial. Wi-Fi, with peak TX currents of 200mA or higher, cannot rely on coin cell batteries, but BLE radios are designed for such batteries.
BLE Physical Layer Radio
BLE introduces a new radio that modulates similarly to classic Bluetooth at 1 Mbps but differs in some ways. Let’s dive deeper into the BLE physical layer. The physical layer refers to the radio itself:
Bluetooth Low Energy
BLE uses the same 2.4GHz ISM frequency band as traditional Bluetooth and Wi-Fi, which is “unlicensed” and doesn’t require FCC certification for use, making it available globally. The band ranges from 2400MHz to 2483.5MHz. The Bluetooth LE specification divides the band into 40 1MHz spaced channels (2MHz wide). This is half the number of channels used in traditional Bluetooth, simplifying some radio designs. Three of these channels are reserved for broadcasting, used by devices to send beacon data packets (broadcast packets). These packets contain information allowing other devices to connect, but they can also offer details about the device.
To avoid interference from Wi-Fi signals and other sources of radio noise, the broadcast channels are strategically placed at the lower, upper, and middle parts of the frequency band. For example, Wi-Fi modules can occupy 20MHz to 40MHz of bandwidth. By distributing broadcast channels, Wi-Fi base stations are less likely to interfere with all channels. For instance, if channel 38 and its surrounding channels are affected, the other broadcast channels 37 and 39 will remain unaffected.
BLE Bluetooth radios transmit using 1 Mbps or 2 Mbps modulation schemes, suitable for radios that support the Bluetooth 5.0 specification. Most radios (if not all) available today are compatible with Bluetooth 5.0, though some older devices are not. The 2Mbps PHY (Physical Layer) enables faster data transmission, usually at the cost of range. Bluetooth 5.0 also introduced CODED PHY, where transmissions using 1 Mbps modulation utilize bits for redundancy (called coding in wireless terms). This allows for error correction, effectively improving noisy signals.
One thing often not explained is the trade-offs involved. 1 Mbps is the standard modulation used for most broadcasts. Using 2 Mbps requires the radio to negotiate. For it to work, both ends of the connection must support Bluetooth 5.0. The 2Mbps PHY is mandatory for Bluetooth 5.0, but long-range Bluetooth support is optional. Smartphones support 2Mbps PHY, but we haven’t yet seen one that supports LE long-range. Part of the reason is that long-range is typically an industrial requirement.
Bluetooth 5.0 also supports output power up to +20dBm, which is the maximum limit achievable. Previously, +10dBm was the highest transmission power, but most BLE radios support up to around +4dBm, with few exceptions. Such high output power allows BLE to cover very long ranges. BLE’s flexibility in both speed and output power allows application design to be optimized, making BLE a powerful solution for many use cases.
To build a BLE product, it’s not necessary to dive deeper into the physical layer, but a basic understanding of RF (radio frequency) design is helpful. Like all wireless transmitters, BLE Bluetooth devices send and receive RF signals, which require antennas and carefully designed RF circuits. Antenna design is a complex subject, but any 2.4GHz antenna can be used. PCB and chip antennas are the most common types.
Recommended BLE Modules
Product 1: E104-BT52X BLE 5.0 Bluetooth Module
Chip Solution: DA14531
Operating Frequency: 2.402–2.480 GHz
Bluetooth Protocol: BLE 5.0
Communication Range: 130 meters
Dimensions: 10×10 mm
Weight: 0.4±0.1g
Overview: The E104-BT52X is a Bluetooth module based on Bluetooth 5.0, offering serial to BLE communication. Its compact size and low power consumption make it suitable for smart wearables, home automation, personal health devices, smart appliances, and industrial IoT applications.
Product 2: E104-BT53C3 Automotive-grade High-Temperature Bluetooth Module
Operating Frequency: 2402–2480 MHz
Bluetooth Protocol: BLE 5.2
Communication Range: 170 meters
Dimensions: 23×16 mm
Weight: 1.3g±0.1g
Overview: The E104-BT53C3 is a Bluetooth module based on BLE 5.2, designed for automotive applications with high-temperature resistance and robust interference resistance. It’s based on Silicon Labs’ EFR32BG22C224F512IM40-C chip and is suitable for use in temperatures ranging from -40°C to +125°C. This module is easy to operate with universal AT commands, making it ideal for automotive, smart wearables, and industrial IoT applications.