Bluetooth

Classic Bluetooth & Bluetooth low energy - what's the difference? Bluetooth 4.0, 2.1+EDR?

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• published: 22 Apr 2013
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A quick introduction to the differences between Classic Bluetooth technology and Bluetooth low energy technology, Bluetooth 4.0, use cases and products. Bluetooth v4.0 which features low energy technology was launched in 2011. Classic Bluetooth is also part of v4.0, but is more typically referred to in, for instance, v2.1+EDR. Important to note is that both flavors will be used, but they will be used differently. In a Bluetooth application where streaming data is used, Classic Bluetooth technology is typically the preferred choice as it achieves substantially greater throughput than Bluetooth low energy technology. Bluetooth low energy technology enables new applications and is ideal for applications requiring episodic or periodic transfer of small amounts of data. Bluetooth low energy also features ultra low power consumption, quick connection times, large number of so called slaves and the advertising functionality. Classic Bluetooth and Bluetooth low energy both have their strengths and weaknesses. For instance, data transfer rates with Classic Bluetooth using Enhanced Data Rate (Bluetooth v2.1 + EDR) can exceed 2 Mbps (actual payload), but practical transfer rates for Bluetooth low energy are below 100 kbps. Many robust features of Classic Bluetooth technology are inherited in Bluetooth low energy technology including Adaptive Frequency Hopping (AFH) as well as part of the Logical Link Control and Adaptation Protocol (L2CAP) interface. In Bluetooth low energy the number of slaves can be very large; how large depends on the implementation and available memory. A Bluetooth low energy device has very low power consumption since it is in sleep mode most of the time. In Bluetooth low energy technology the actual connection times are of only a few mS and thereby the connection is quickly initiated as the device wakes up. Smartphones and tablets are widely used in everyday life. By installing a tailored app, the everyday smartphone or tablet becomes a powerful and cost efficient tool for industrial applications. Because the two technologies are fundamentally different from an application perspective, one either implements single-mode or dual-mode solutions depending on one's need. On the left, you see Classic Bluetooth implementations which are to be used in Bluetooth applications where streaming data is used. To the right, you see single-mode Bluetooth low energy devices. These devices are also known as Bluetooth Smart devices and are optimized for small battery-operated devices with low cost and low power consumption in focus. A typical single-mode device is for example a heart rate sensor or the connectBlue Bluetooth low energy serial port modules OLS425 and OLS426. In the middle are dual-mode devices. These devices are also known as Bluetooth Smart Ready devices and include both Bluetooth low energy and Classic Bluetooth. A typical dual-mode device is a smartphone, PC or the connectBlue Bluetooth Serial Port Module OBS421. Unlike Classic Bluetooth, product developers can develop their own profiles and services to add to those from the Bluetooth SIG. For example, connectBlue, now a u-blox company, has developed the cable replacement service named the connectBlue Low Energy Serial Port Service. This service is GATT-based and offers transparent serial communication and thus is of importance in industrial and medical applications where Bluetooth low energy is used. The central always makes the scan (or look for advertisements) and the peripheral always makes the advertisement. The basic idea is that the peripheral is in low-power mode most of the time (to save power) and when it is woken up, it starts advertising. The central is always scanning and when a "correct" peripheral is found, a connection is initiated. If you want to get started smoothly with your u-blox connectBlue low energy product, have look at our Getting Started document on our Support Site. Visit connectBlue's website on connectblue.com to learn more about our products and more in depth details on the technology differences.