By Majeed Ahmad
Bluetooth Low Energy (BLE)—also known as Bluetooth Smart—is unmistakably the future of information flow in wearable devices. The wearable design is in an embryonic stage now and so are BLE-centric product designs.
The blog takes a peek at the prevalent design challenges that engineers face in the Bluetooth realm on the day-to-day basis; the blog also suggests tips and tricks on how to get around them.
The Bluetooth technology has gone through a non-stop evolution since its inception in 1998. However, if there is one thing that hasn’t changed much, it’s the pain in interfacing the Bluetooth part with other design building blocks like audio amplifier and microcontroller.
For a start, as a user writes in the post “Interfacing Bluetooth Module with Microcontroller” on the EDAboard.com, check the datasheet carefully. For instance, regarding the Bluetooth interface to an MCU, there is always a digital interface to connect to the peripheral parts of the MCU, whether it’s UART, USB, SPI or I2C.
Bluetooth is one of the primary RF communication solutions in the Internet of Things (IoT) arena, and here, a prevailing issue is managing RF reception while connecting Bluetooth to devices like the audio amplifier. For instance, take the case of a developer who is facing another kind of interfacing challenge: The creation of noise while connecting the Bluetooth part to class D amplifier.
It could be either due to RF picked up by the amplifier input or the Bluetooth output interfering with amplifier causing distortion or hiss. The other possibility is that the level of Bluetooth output is too high. In any case, it’s advisable that designers ensure the isolation of power or signal. Moreover, it can be a ground referencing problem, so ensure that Bluetooth output is not floating and that it’s properly related to ground.
Application do’s and don’ts
Remember Apple Watch? The most popular wearable device of 2015 uses Bluetooth to connect to the iPhone; but it switches to a Wi-Fi link when higher data transfer rate is required. That’s because Bluetooth hasn’t been designed for very high data rates.
The ultra-low-power BLE connections are ideal for high-quality audio communications, for instance, but pairing large video files is entirely another matter. So, when a forum user aims at connecting the recording camera to a USB on a mass storage device, his design comrades advise him caution. Eventually, Dora, a super moderator on EDAboard, is able to convince the design engineer to switch to Wi-Fi connectivity.
OS platform implementation
The wearable product developers are increasingly looking to Bluetooth for creating apps that can function while wearables are hooked to smartphones. Take the example of an engineer trying to develop an Android-based blood pressure monitor. A fellow engineer recommends Bluetooth as the top connectivity option.
However, developers should carefully review the Bluetooth stacks whether it’s Android, Android Wear or iOS. Case in point: an app developer is able to send and receive data from an Android device to his board but can’t do that for an iOS device. That’s because Apple has blocked many features in its Bluetooth stack for iOS.
It’s worth noting that now a number of new Bluetooth chips come with built-in applications support for both Android and iOS platforms.