Design and implementation of ultra low-power controller SoC for body sensor network

Abstract

Gathering and analyzing vital signals everyday life using mobile healthcare service can detect intermittent symptoms which cannot be found in a hospital as well as conventional disease. And powerful therapy algorithm and external communication block enables automatic first aid treatment and asking for help. Such service is very useful for acute disease and increases restoration ratio. Implementing such mobile healthcare system requires sensor nodes to gather various vital signs such as body temperature, pulse, heart rate and blood pressure, a network system to collect the data and a processor to analyze the data and control the system. This research provides a centralized body sensor network (BSN) system optimized for managing human body sensors and sensing data. In the proposed network system, a network controller manages all the sensor devices and generates the data-request command for each device with the programmed period in the controller. The centralized control eliminates the communication conflict among the sensor devices and it can enhance the energy efficiency in the data communication. The controller operations are categorized into energy-aware operations and performance-aware operations, and the controller works in two modes, MANAGE mode and ALERT mode, according to the operations. The controller has two system masters, a low power schedule director (SD) and 16-bit RISC. In MANAGE mode, SD with TCAM-based periodic event generator (PEG) manages all the sensor nodes and it activates the RISC only when it is needed with ALERT mode. The proposed instantaneous program execution with external program counter (IPEEP) scheme enables the event-driven operation to the RISC by activating the RISC from the power-save mode with conventional CPU reset sequence. The proposed scheme reduces both the activation time and corresponding energy consumption. The proposed controller system is implemented with 0.18-um logic process and the test system board is also i...