Qualcomm has added a new chip to its range for smartwatches, this one designed to address a common criticism of the form factor, poor battery life. The Snapdragon Wear 3100 is an ultra-low power coprocessor, running a very stripped-down real time operating system (RTOS) to extend battery life.
The chip company claims the 3100 can power a watch for 4-12 hours longer between charges than its predecessor. That prolongs battery life typically to a month, provided Google’s Wear OS is turned off.
The power savings mainly come from hosting the basic watch functions, which run all the time, on a new 40 MHz ARM M0 microcontroller core running at 0.6 V, in a homegrown software environment which Qualcomm describes as a basic scheduler. In sleep mode, the 21-mm2 QC1110 draws just 130 µA, compared to about 1.2 mA for a typical smartwatch processor based on an ARM Cortex-A7, and required to run a full operating system like Wear OS.
Qualcomm estimates that consumers use the interactive functions that require Wear OS for only 5% of the time, and the rest of the time, the main processor can sleep. That main CPU now runs on four A7 cores running at 1.2 GHz, up from a single A7 in the previous chipset.
Users can switch in software between Wear OS and basic smartwatch mode, to conserve battery life; or the chip’s power management software can automatically shut down the A7 and move work to the coprocessor after a period of inactivity.
Qualcomm designed a custom SRAM block to support the coprocessor’s near-threshold operation. The coprocessor also contains a custom block to listen for and detect wake words from a voice assistant. The 3100 comes in versions supporting LTE, GPS, or Bluetooth and WiFi.
Customers for Snapdragon Wear include Asus, Huawei and LG, plus more than a dozen fashion watch vendors.