Use multiprotocol wireless modules to simplify IoT product design and certification
one or more shunt inductors and series capacitors. The designer’s challenge is to choose the best network topology and component values. Manufacturers often offer simulation software to help with matching circuit design, but even after following good design rules, the resulting circuit can often exhibit disappointing RF performance, lacking range and reliability. This leads to more design iterations to revise the matching network (Figure 2).
Figure 4: The Setebos-I 2.4 GHz radio module includes a pin for an external antenna (ANT) to extend the radio’s range. Image source: Würth Elektronik
The advantages of a module
downsides, then a module is the answer. One example that uses the Nordic nRF52840 at its heart is Würth Elektronik’s Setebos-I 2.4GHz radio module 2611011024020. The compact module measures 12 × 8 × 2mm, has a built-in antenna, a cover to minimise electromagnetic interference (EMI), and comes with firmware to support Bluetooth 5.1 as well as proprietary 2.4GHz protocols (Figure 3). As described above, the SoC at the heart of the module is also capable of supporting Thread and Zigbee – with the addition of appropriate firmware. The module accepts a 1.8-to-3.6- volt input, and when in sleep mode, draws just 0.4 microamperes (µA). Its operating frequency covers the Industrial, Scientific, and Medical (ISM) band, which is centred on 2.44GHz (2.402 to 2.480GHz).
and end-device packaging – can dramatically affect RF performance.
There are some advantages to designing a short-range wireless circuit using discrete components, notably lower bill-of-material (BoM) costs and space savings. However, even if the designer follows one of the many excellent reference designs from SoC suppliers, other factors – such as component quality and tolerances, board layout and substrate characteristics,
An alternative approach is to base the wireless connectivity around a third-party module. The modules are fully assembled, optimised, and tested solutions that enable ‘drop-in’ wireless connectivity. In most cases, the module will already be certified for use in global markets, saving the designer the time and money needed to pass RF regulation certification. There are some downsides to module use. These include increased expense (depending on volume), larger end-product size, reliance on a single vendor and its ability to ship in volume, and (sometimes) a reduced number of accessible pins relative to the SoC upon which the module is based. But if design simplicity and faster- time-to-market outweigh these
Figure 3: The Setebos-I 2.4 GHz radio module comes in a compact form factor, has a built-in antenna, and comes with a cover to limit EMI. Image source: Würth Elektronik
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