Silicon Labs Hits the Sidewalk

Silicon Labs’ EFR32G23 and -28 support Amazon’s Sidewalk protocol. One transmits using subGHz FSK; the other FSK and Bluetooth. The company provides the full software stack.

Bryon Moyer

Silicon Labs’ new EFR32SG23 and EFR32SG28 microcontrollers are among the first to target Amazon’s Sidewalk communication protocol. They allow systems to connect to Amazon’s Echo appliances, whether in one’s home or near someone else’s, simplifying IoT connections to the internet.

The Sidewalk protocol allows simple low-bandwidth, low-power IoT devices to connect to the cloud through Echo smart speakers (and some Ring cameras) in homes that have the feature enabled. Amazon turns on the feature by default; users who don’t want others communicating on their network must shut it off.

Sidewalk is a multiradio system that can employ Bluetooth Low Energy, simple subGHz frequency-shift keying (FSK), or LoRa radios—or a combination of all three. The different radios enable different communication distances, potentially combining an entire neighborhood into a virtual network.

Both chips feature Cortex-M33 CPUs for application code. They differ in memory quantity, radio protocol coverage, and number of general-purpose I/Os. The SG23 supports only FSK; the SG28 adds Bluetooth; neither handles LoRa. The latter chip also favors larger multisensor systems, conferring additional memory and I/Os. In production now, the SG23’s list price is $2.44 and up; the SG28 starts at $4.54 (1,000 pieces).

Amazon has opened system development only this year; companies implementing it must obtain a free license from Amazon. Some suggested applications, such as door open/closed sensors and gas-leak detectors, are typically stationary in-home units that will remain on the home’s network. Others, such as pet trackers, are more likely to operate outside the home; they’ll benefit from any surrounding Sidewalk support.