Once the design decision is made to take the module approach to adding Bluetooth Low Energy (BLE) connectivity to an IoT design, developers need to give serious consideration to which module they will employ. While they all provide connectivity, there are subtle differences in architecture, configuration, and power – among many other factors – that need consideration. Fortunately, the breadth of choices available is considerable.
Making sense of the myriad choices requires consideration of many factors. Here are some of the key factors to include when choosing a BLE module for your next design.
Cost – For many applications, cost is the critical concern. As pointed out in Part 1 of this series, however, the total cost of ownership associated with a module choice may outweigh the module's unit cost as the important factor. This total cost includes any added development time, certification expenses, tool and software purchases, and post-deployment maintenance efforts associated with device choice. Key questions to ask a vendor beyond unit pricing include the type and nature of hardware and software development and integration support offered (including for cloud services and mobile app development), availability of local regional support, vendor experience level with the technology, need for external components, compliance versus actual certification and listing, and upgrade path to emerging standards such as Bluetooth 5.
Size – The amount of PCB board space a module occupies can be critical in some applications, and can have an impact on the cost and complexity of the PCB needed to support the device. In applications such as wearable devices, the module's height might also be a critical concern.
Hosted or hostless architecture – Some BLE modules are designed to be drop-in communications peripherals with the transfer of messages as their sole function. Such modules work as a “black box” attached to a host processor that is handling all other device operations, simply executing their host's setup and data transfer commands. Other modules are “hostless,” stand-alone devices that serve both as a user-configurable system controller and the BLE peripheral. Many modules can serve in either architecture, sometimes requiring additional software or development effort to be hostless, however.