Previously, a designer had to choose one wireless technology and then redesign the product if there was a demand for a variant using a different protocol. But because the protocols use PHYs based on a similar architecture and operate in the 2.4GHz spectrum, many silicon vendors offer multiprotocol transceivers.
power consumption is similar. Zigbee is not interoperable with smartphones, nor does it offer native IP capability. A key advantage of Zigbee comes from it being designed from the ground up for mesh networking. Thread, like Zigbee, operates using the IEEE 802.15.4 PHY and MAC and has been designed to support large mesh networks of up to 250 devices. Where Thread differs from Zigbee is through its use of 6LoWPAN (a combination of IPv6 and low-power WPANs), making connectivity with other devices and the cloud straightforward, albeit via a network edge device called a border router. (See, A Brief Guide to What Matters in Short-Range Wireless Technologies. ) While standards-based protocols dominate, there is still a niche for 2.4GHz proprietary protocols. Though they limit connectivity to other devices equipped with the same manufacturer’s chip, such protocols can be finely tuned to optimize power consumption, range, interference immunity, or other important operational parameters. An IEEE 802.15.4 PHY
and MAC is perfectly capable of supporting 2.4GHz proprietary wireless technology. The popularity of these three short-range protocols and the flexibility offered by 2.4GHz proprietary technology makes it difficult to choose the right one to suit the widest set of applications. Previously, a designer had to choose one wireless technology and then redesign the product if there was a demand for a variant using a different protocol. But because the protocols use PHYs based on a similar architecture and operate in the 2.4GHz spectrum,
Thread network.
Nordic Semiconductor’s nRF52840 SoC supports Bluetooth LE, Bluetooth mesh, Thread, Zigbee, IEEE 802.15.4, ANT+, and 2.4GHz proprietary stacks. The Nordic SoC also integrates an Arm Cortex-M4 MCU – which looks after the RF protocol and application software – as well as 1 megabyte (Mbyte) of flash memory and 256 kilobytes (Kbytes) of RAM. When running in Bluetooth LE mode, the SoC offers a maximum raw data throughput of 2 megabits per second (Mbits/s). The transmit current draw off its 3-volt DC input supply is 5.3 milliamps (mA) at 0 decibels referenced to 1 milliwatt (dBm) of output power, and the receive (RX) current draw is 6.4 mA at a raw data rate of 1 Mbit/s. The nRF52840’s maximum transmit power is +8 dBm and its sensitivity is -96 dBm (Bluetooth LE at 1 Mbit/s).
many silicon vendors offer multiprotocol transceivers.
These chips allow a single hardware design to be reconfigured for several protocols simply by uploading new software. Better yet, the product could be shipped with multiple software stacks, with switching between each supervised by a microcontroller unit (MCU). This could allow, for example, Bluetooth LE to be used to configure a smart home thermostat from a smartphone before the device switches protocols to join a
The importance of good RF design
While wireless SoCs such as Nordic’s nRF52840 are very
52
Powered by FlippingBook