Low-power control technology for wearables

Toshiba has developed an innovative low-power control technology for microcontrollers supporting multisensor wearable devices.

The goal for battery-operated wearable devices is a long run time without charging, with a physically small battery. This requires power-saving technologies. MCUs embedded in wearable devices typically support several low-power modes - ie, the devices are idle automatically. But the transition from low-power mode to active mode requires some power consumption. This requires wearable devices to reduce the frequency of mode transition. However, the number of sensors embedded in wearable devices is increasing, requiring the microcontroller to respond to sensors more frequently, with a mode transition every time it does.

Toshiba’s technology reduces the frequency of the mode transition by gathering the separate data acquisitions from multiple sensors which get data at their own regular intervals. In this way, the number of mode transitions can be decreased; hence, the reduction of power consumption from mode transitions is achieved. On the other hand, if aggregating leads to significant failures in data acquisitions, it will have a considerably negative impact of the functions of the application, such as step measurement or behaviour analysis in activity monitors. Toshiba has developed an aggregating method that optimises timing of data acquisition to suppress failures.

To evaluate the method, Toshiba ran an activity-monitoring application on its TZ1001MBG application processor for wearable devices. The result showed a 31% power reduction, proving efficient power-saving technology. Toshiba has now embedded this technology into the TZ1000 series MCU.