IoT Bluetooth Chips – Technology, Design and Module Selection Considerations
Bluetooth is a global wireless technology for simple, secure and point-to-point connectivity based on IEEE 802.15.1 standard. Created as an open standard to allow connectivity and collaboration between disparate products and industries, Bluetooth is building personal area networks (PANs). The technology is introducing new possibilities for devices and certainly modifying the consumer behaviour.
Bluetooth chips enable devices to communicate via a standard radio frequency instead of through cables, wires or direct user action. The data can be exchanged over short distances using short-wavelength UHF radio waves in the ISM band (Industrial, Scientific, and Medical radio band ) from 2.4 to 2.485 GHz from fixed and mobile devices. Bluetooth has expanded to short-range networking, although designed to replace short-range cable protocols.
Bluetooth is enabling a global vision to connect devices ranging from mobiles to automobiles, medical equipments to manufacturing plants, wearables to consumer electronics, and fulfillment centers.
Bluetooth SIG (Special Interest Group):
The working group creates the Bluetooth Core Specification and services. They ensure the specification and layers of services work at the highest interoperability standards. Bluetooth devices requires FCC and Bluetooth SIG certification.
Bluetooth compliance versions are SIG 1.0, SIG 1.0b, SIG 1.1, SIG 1.2, and SIG 2.0.
There are three main power classes as defined by Bluetooth. Power control is used to keep the radiation within the limit so that the system works efficiently without interfering with the neighbour bluetooth devices. The power control algorithm is designed between master and slave devices using link management protocol.
Class I Bluetooth chips are used in the most powerful devices, Class II in mid-range applications while Class III belong to the least powerful broadcast use cases.
Bluetooth Technology Versions:
There are numerous versions of Bluetooth technology, from V1.0, V1.1, V1.2, V2.0 and V2.0 etc, to the latest V4.0, V4.1 and V4.2.
Bluetooth BR/EDR (Classic Bluetooth):
Referred to as Basic Rate/Enhanced Data Rate, the specification version 2.1 allowed consumers to select “add Bluetooth device” from the connection menu to let devices automatically find and connect to each other. The EDR chips move data at faster rate compared to standard Bluetooth chips.
The classic Bluetooth assures the data transmission rate and hence suitable for applications such as headset transmitting high quality music, etc.,
Bluetooth High Speed:
The version 3.0 uses a data-substitution method that offers faster throughput via momentary use of a secondary radio that is already present in consumer devices. The technology lets the users to quickly send video, music and large files between the devices.
Bluetooth Low Energy (BLE, Bluetooth LE, marketed as Bluetooth Smart Ready)
The power-efficient BLE (version 4.0) is suitable for devices that run for long periods on power sources (coin cell batteries, energy-harvesting devices). The developer friendly environment, interoperability across platforms, 128-bit AES data encryption and low energy consumption makes BLE suitable for IoT (Internet of Things).
Bluetooth 4.2 features improved speed and privacy over Bluetooth 4.1(also known as Bluetooth Low Energy or Bluetooth Smart) but the main advantage is allowing chips to use Bluetooth over Internet Protocol version 6 (IPv6) for direct Internet access.
Bluetooth 4.2 superior over Bluetooth 4.1:
BLE 4.2 has better features compared to BLE 4.1 - Features include IoT capabilities such as Low-power IP (Ipv6/6LoWPAN), Bluetooth Smart Internet Gateways (GATT), Low Energy Privacy 1.2, Low Energy Secure Connections compared to previous versions. BLE 4.2 enables 250% faster and more reliable over-the-air data transmission and 10x more packet capacity. Also, BLE 4.2 Bluetooth Smart sensors can transmit data over the internet.
Focussing mainly on IoT Universe, the latest version released on 6th December 2016 include faster speed, larger broadcast message capacity, longer range, as well as improved interoperability. Bluetooth 5 includes updates that reduce potential interference with other wireless technologies. They enable new possibilities with beacons and location-based services along with greater flexibility in targeting multiple applications and use cases.
1. For classic Bluetooth, there are 79 channels in total, and the band interval is 1 MHz. This includes the 2 MHz guard interval at 2.400 GHz (the bottom end) and 3.5 MHz at 2.4835 GHz (the top end).
2. The most common transmission rate for Class II electronic devices is +4 dBm, and the sensitivity range of receiver is -90 dBm.
3. The Bluetooth Smart ready is a better choice if the device needs to communicate with both the devices equipped with the Classic Bluetooth and low-energy Bluetooth.
Components of Bluetooth Solution:
Bluetooth Baseband Controllers:
They are the combination of link controller, link manager, protocol stack, and host controller interface firmware of the Bluetooth specification in a single IC chip(integrated circuit).
Bluetooth RF Transceivers or Radio Modems:
They are the transmitters and receivers that comply with Bluetooth SIG requirements and operate in the 2.4 GHz range.
The IP cores which can be loaded into application-specific integrated circuits (ASICs) or field-programmable gate arrays (FPGAs).
Bluetooth Development Kits:
The standard design environments to develop Bluetooth-compliant hardware and/or software applications.
Emphasize on ‘Cost versus Skills versus Time’ to select between Bluetooth Module and Bluetooth Single Chip (Discrete)
Are you in a dilemma to choose between Bluetooth Module or Bluetooth Single Chip?
Then, here is the information given to understand what parameters may lead to make the right choice between the module and the single chip solution.
Bluetooth chipset design needs the developer to perform RF and hardware designs, layout the Bluetooth chipset as well as add the extra parts like power supply, oscillator, resistor, capacitor, antenna, balun, etc., Although it’s complicated than selecting a ready module, the flexibility of design as per the exact requirement can be achieved. It’s cheaper but involve expertise RF skills, compliance certifications and time consuming. There’s a huge benefit returned if the in-house designed Bluetooth solution is intended for use in multiple products.
Bluetooth module contain necessary components (such as low energy chipset, chip antenna, oscillator, resistors, capacitors, etc.,) on itself and is fairly simple to use. The module require power supply, flash the firmware and start working with it, mostly the firmware design portion(while skipping hardware design). CE and FCC qualifications are already provided by most of the module suppliers and hence the developers save time on product releases. Module is costlier but simulataneously carry the advantage of allowing to do quick prototyping and choosing very small footprints (standard packages).
Few technical parameters have considerable amount of role to play in the overall Bluetooth solution (irrespective of module or discrete chip). To precisely note them,
1. The RF design is the critical stage to achieve the best link and range in the system.
2. Memory and flash: Number of BLE connections are dependent on RAM sizes and it’s important to understand what the stack can handle.
3. Able to support IPv6.
4. Programmable digital and analog features capability.
5. Number of GPIOs (general-purpose input/output - in case of integrated BLE chipset)
6. Peripherals available on the device.
7. Power consumption: Having large BLE peak currents and in few cases the current drawn in shutdown mode could reduce the capacity.
8. Bus Interfaces commonly supported by Bluetooth are USB, PCI, IEEE 1394 (Firewire), SPI, UART, I2C, etc.,
How to Select a Bluetooth Module?
The hardware and software components of the Bluetooth module collectively works as a complete Bluetooth solution only when embedded into a proper system.
A Bluetooth chip and an application processor forms the hardware section along with I/O interfaces, timers, ADCs, DACs, oscillators, etc., The processor also have internal or external flash memory, RAM and ROM.
The user operation, developer management, security and controls are facilitated with the help of application software residing in the Bluetooth module.
The bluetooth modules usually are classified by the transmission distance, transmission rate, frequency band, certification, packaging size, etc., by the module manufacturers. But, while selecting the Bluetooth module, there are other parameters to evaluate. Few of them are:
1. Bluetooth Protocols / Standards
2. Transmission output power
3. Operating current / voltage
4. Microprocessor / Microcontroller
5. Antennas and Interfaces
6. Hardware Interfaces....etc.,
Many of us get into a situation where we couldn’t conclude on selecting the right Bluetooth module from the given list of suppliers. The bottleneck can be in prioritising the attributes and understanding their importance in the product. Here is where the Engineering expertise comes to the picture.
Based out of several applications and interactions, it’s found that most of the designers choose the Bluetooth module by first considering coverage range, transmission rate and compatibility over cost, battery life and design complexity. The same is denoted in the above diagram to show the trade-off during module selection.