Everything starts from connection. The Internet of Things (IoT) is accelerating its entry into our daily lives and all walks of life. The connection and interaction between people and things, things and things are becoming more and more intelligent and convenient, and wireless communication has become the Internet of Things connection. Mainstream communication technologies such as Bluetooth, WiFi, ZigBee, etc. have their own merits in the application of the Internet of Things, and have become a strong support for the implementation of the Internet of Things.
Choosing a Bluetooth module: three considerations
When choosing Bluetooth or other RF modules for Internet of Things (IoT) devices or certain other projects, you may find that there are many more feasible solutions on the market than you think. Under normal circumstances, module manufacturers or suppliers will classify the thousands of modules provided according to transmission rate, transmission distance, frequency band, certification, packaging size, etc.
It is important to consider all aspects, but certain factors are more critical. By putting the most important emphasis on transmission rate, transmission distance (or coverage) and power consumption, you can effectively narrow the range of options. After making a balance between these factors, choosing a module on this basis can help you make decisions that directly affect the end user experience. We will quickly examine these parameters and how they affect the performance of your device.
1) Transmission rate
Transmission rate or data rate is usually the first thing that designers and developers consider because it forces designers and developers to consider the type of information that needs to be transferred between devices. For example, the data rate required to transmit high-quality music to headphones is very different from the data rate required by a basic heartbeat monitor.
In theory, the transmission rate of low energy Bluetooth does not support its own maximum bandwidth (1 MHz), because the focus of low energy Bluetooth is simple information transmission. If data is transmitted at a high rate, Bluetooth Low Energy will consume more power, which is contradictory to the original design concept. If high-speed transmission is required, then EDR Bluetooth or Wi-Fi with a higher rate should be considered. Any increase in speed will almost inevitably consume more power.
2) Power category and transmission distance coverage
On the websites of manufacturers and distributors, Bluetooth modules are divided into categories, where the category refers to the power category. The higher the power category, the farther the transmission can reach. Like any other wireless technology, Bluetooth networks have limited distance. The transmission distance varies with different versions. In the same version, the supported transmission distance will still vary with different power categories.
The actual signal transmission distance varies with specific environmental conditions, such as transmission conditions, materials, manufacturing deviations, antennas and batteries. In addition to the requirements specified in the Bluetooth standard, the device also needs to meet the power requirements specified by the local government spectrum regulatory agency.
3) Power consumption
The power consumption is mainly related to the transmission rate and distance. Since Bluetooth devices are generally powered by batteries, the operating current/voltage of the device is an important consideration because it directly determines the charging time and battery life cycle.
By further dividing the module into different versions, the Bluetooth SIG simplifies this early decision. The Bluetooth technology version is divided into a classic version and a low energy (LE) version. Economic Bluetooth versions 1, 2 and 3 are optimized for data transfer rates. In the classic version, it is divided into basic rate (BR), enhanced data rate (EDR) and high speed. Bluetooth Low Energy puts more emphasis on simple information transmission while extending the battery life of electronic devices as much as possible.
In addition to these categories, the manufacturer will list the transmit and receive current and/or power, which are mainly used in module selection. If you can test the intended end device use, then you can more easily evaluate the module and balance the various factors in the specific application.
To find an appropriate Bluetooth module, first balance the transmission rate, transmission distance, and power consumption. Once the selection range is reduced, the range can be further narrowed based on cost, space, and compatibility. Finally, it is expected that you can use test equipment to do some evaluation of the module. Download the How to Choose Bluetooth Module Application Guide to learn more about this test.
Ensure that the Bluetooth design passes EMI compliance testing
Before any new device that supports Bluetooth is on the market, whether it is a complete communication device or a simple USB dongle, it must meet the strict EMI radiation requirements set by the FCC.
In the past, designers generally had to wait until the end of the design cycle before sending the product to the testing organization for formal conformance testing. Unfortunately, in more cases, many Bluetooth designs will not be passed over again. The cost of several trips to the testing organization will be very high, depending on the root cause, it is easy to cause delays in the construction period and fail to complete the project on time.
A much better method is to perform a pre-compliance check in advance so that any EMI problems can be identified and corrected. Intuitively, many designers think that they do not have the equipment or expertise to complete pre-compliance testing.
The pre-compliance test is of great significance and can ensure that you pass the EMI/EMC compliance test in the testing organization. By using appropriate equipment, Bluetooth wireless testing can also be performed easily.
This article introduces the selection of Bluetooth modules and EMI pre-compliance testing. This is a problem that engineers often face when designing Bluetooth modules, and it is also a problem that often causes headaches. There are many more options than imagined, and the focus of selection should be on the transmission rate, transmission distance (or coverage) and power consumption, which can effectively narrow the range of choices. The EMI pre-compliance test can effectively reduce the design and development time and cost.