Most electronic engineers are not wireless experts. They’re typically not taught radio and RF in most BSEE degree programs. Wireless may be an elective, but most students seem to opt for more digital, micros, and programming. Yet today, wireless is so widely used that it’s inevitable for many EEs to have to design a wireless product or system, most likely related to the Internet of Things (IoT). Maybe you’re one of them. Even if you’re a rank novice in wireless, you can still design like a wireless expert and succeed.
Choosing the Wireless Technology
The wireless selection is based on the specific application, with most use cases involving remote sensor monitoring. Multiple technologies are available, and choosing the best option requires evaluating the application based on three key characteristics:
- Power consumption: Low power is usually the most important, as it will maximize the interval between battery changes in the remote nodes.
- Range: Short range (SR) < 100 meters. Long range (LR) > 100 meters to 10 km.
- Speed: Low speed is 100 bits/s to 10 kbits/s. High speed is 100 kbits/s to 10 Mbits/s.
The Wireless Possibilities
At least a dozen standards are vying for the billions of IoT applications. The most popular technologies are Bluetooth Low Energy (BLE), Wi-Fi, Zigbee, Z-Wave, and Thread. These are primarily short-range standards. For long range, you can select LoRa, Sigfox , Weightless, and the cellular-based LTE-M and NB-IoT. Consider each technology through the application’s needs.
After selecting a standard, you can start the design. Designing the radios is a challenge, but chips are available to implement virtually any technology. The typical IC is a system-on-chip (SoC) with the radio and a companion MCU.
What About Modules?
An alternative, smarter design choice is to use pre-built modules. Modules package the SoC along with all of the necessary support circuitry, including the antenna and its matching network, on a PCB. These practically eliminate the RF design process. This leaves you free to focus on software. Using modules offers these advantages:
- No RF design experience necessary.
- Little need for any expensive RF test instruments costing tens of thousands of dollars.
- No need for PCB design, antenna selection, or Z matching design. All require some prior RF experience.
- Elimination of the expensive and required wireless testing and certification processes by the FCC and/or the standards body related to your technology. Modules are pre-certified.
The main downside is that modules are a bit more expensive than chips, but there are major savings based on the advantages mentioned above that offset that extra cost. Do the math on the savings and you will see. Furthermore, by using modules, you will bring your product or system to market sooner.
Some IoT chip manufacturers like Silicon Labs also offer modules. Check out the company’s wireless modules for the most popular standards like Wi-Fi, Bluetooth, Thread, and Z-Wave. One example is the Blue Gecko series SiP modules for Bluetooth Low Energy (see figure). The BGM12x packages a full BLE radio, an ARM Cortex-M4 MCU, and related I/O. Even the antenna is integrated into the module. A variety of other module form factors are available as well as multiprotocol versions. Starter kits and lots of development software support the modules.