The emergence of low-energy Bluetooth devices has inspired many electronic developments and innovations. Also known as Bluetooth LE, this technology has made its way to a variety of applications. For example, many IoT and medical devices incorporate Bluetooth LE technology for communication. In this article, we will compare low-energy Bluetooth with classic Bluetooth technology and look at the advantages, applications, and design considerations for low-energy Bluetooth.
Low-Energy Bluetooth vs. Classic Bluetooth
Despite being an upgrade to classic Bluetooth, low-energy Bluetooth (Bluetooth LE) is starkly different from its predecessor. As the name implies, Bluetooth LE consumes very little power compared to classic Bluetooth. A low-energy Bluetooth transceiver usually consumes less than 15 mA of current in active mode. This allows low-energy Bluetooth devices to operate using a battery for a considerably significant period, making it an ideal communication technology for IoT devices.
In terms of data transfer, classic Bluetooth sends streams of data packets while Bluetooth LE transmits small data packets. A Bluetooth LE device spends most of the time in low power sleep mode and only wakes up when sending data. Meanwhile, a device with classic Bluetooth technology spends most of the time maintaining an active connection, thus draining more power.
Low-energy Bluetooth technology also edges its predecessor in speed and distance. Despite its short active interval, a Bluetooth LE device achieves up to 1 Mbps, while classic Bluetooth only hits 700 kbps. You can also place low-energy Bluetooth devices up to 150 meters apart in an open area, but classic Bluetooth is optimized for short-distance transmission.
Despite improvements that span different generations, both Bluetooth LE and classic Bluetooth might experience coexistence challenges with WiFi devices. Bluetooth transmits data on the 2.4 GHz spectrum, while modern WiFi routers allow devices to connect at the 2.4G Hz or 5 GHz spectrum. Bluetooth might interfere with WiFi transmission on the same spectrum if both transmission paths are less than 10 meters from each other.
Despite this, there are still many advantages to low-energy Bluetooth devices. Let’s explore these next.
Advantages of Low-Energy Bluetooth Devices
As we discussed, the primary advantage of low-energy Bluetooth is its ability to provide significantly lower energy consumption than the classic version of Bluetooth.
Additionally, its specific design affords the periodic transfer of small amounts of short-range data. Another advantage is that low-energy Bluetooth technology lends itself to easy deployment. In summary, low-energy Bluetooth consumes approximately half the energy of classic Bluetooth, is cost-effective, and provides a substantial increase in battery life.
Applications for Low-Energy Bluetooth Devices
Bluetooth is used widely through the IoT field of devices.
The following are some of the applications of low-energy Bluetooth. Note that this list is not exhaustive by any means.
Health care: Used in blood pressure measurement devices, temperature measurement devices, and blood glucose monitoring devices.
Mesh profiles (Bluetooth mesh profiles): Used to communicate with other devices on the network. Also, every device can pass information forward to other devices, creating a mesh network. For example, being able to turn off every light in your home with your smartphone.
Sports and fitness devices: Used in sensors attached to exercise bikes to measure speed and crank revolutions per minute, devices that measure heart rate (smartwatches or smart bracelets), and scales to monitor body weight.
Environmental sensing profiles: Used to measure functionality of environmental factors such as illuminance, ambient humidity, ambient temperature, and ambient pressure.
PCB Design Tips for Low-Energy Bluetooth Devices
When designing low-energy Bluetooth devices, you need to pay attention to the following.
Your Bluetooth LE design is most likely to run on a battery. In a low-power design, it is essential to have an accurate estimate of the power budget. This helps you ensure the device will last as long as calculated. Watch for potential current leakage and ensure that you're using a microcontroller that supports low-power deep sleep mode.
Bluetooth LE runs on the 2.4 GHz spectrum. Despite operating on short bursts of low-energy transmission, it may still cause EMI issues to adjacent components. To prevent the high frequency from coupling into sensitive signals, use EMI mitigation strategies such as increasing the distance between traces or adding an EMI shield.
Bluetooth LE transceivers are powered with voltage ranging from 1.8V to 3.6V. Voltage level fluctuation can lead to unpredictable behavior and disrupt Bluetooth transmission. Hence, it is vital to ensure a reliable power delivery network in the design. For example, you will want to add decoupling capacitors near the Bluetooth module to provide a stable voltage level.
Electrical consideration isn't your only consideration if you design smart wearables or medical devices with a Bluetooth module. Often, these products need to fit into their mechanical enclosure. You will need to work with the mechanical constraints by using a PCB design software that supports ECAD-MCAD integration.
Cadence offers a suite of design and analysis tools to help designers implement low-energy Bluetooth technology into their designs. If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.