Reliable Timekeeping for Intermittent Computing
Reliable Timekeeping for Intermittent Computing
复制标题
DOI：
10.1145/3373376.3378464
复制
发表时间：
2020-03
期刊：
影响因子：
--
通讯作者：
Jasper de Winkel;C. D. Donne;K. Yıldırım;P. Pawełczak;Josiah D. Hester
中科院分区：
文献类型：
--
作者：
Jasper de Winkel;C. D. Donne;K. Yıldırım;P. Pawełczak;Josiah D. Hester
能量收集设备使物联网应用成为可能，这在以前是不可能的。间歇运行的无电池传感器的一个核心挑战是可靠的计时。最先进的低功耗实时时钟具有较长的启动时间（秒级），并且具有较低的时间保持粒度（最多数十毫秒），通常不匹配每秒经历多次断电的设备的时序要求。我们的关键见解是，时间可以通过测量替代物理现象来推断，例如简单RC电路的放电，并且可以根据运行时间要求来调节计时能量成本和精度。我们实现这些目标与多层计时架构，命名为级联分层剩磁计时器（CHRT），具有一系列不同的RC电路用于动态计时的要求。CHRT及其附带的软件接口嵌入到一个新的无电池无线传感平台中，称为Botoks，能够在电源故障时跟踪时间。低启动时间（最长5 ms）、高分辨率（最高1 ms）和运行时可重构性是我们的计时平台的主要特点。我们开发了两个对时间敏感的无电池应用程序来演示这种方法：自行车分析工具，其中CHRT用于跟踪自行车车轮旋转之间的时间，以及无线通信，其中CHRT使两个无源供电传感器之间的无线电同步。
Energy-harvesting devices have enabled Internet of Things applications that were impossible before. One core challenge of batteryless sensors that operate intermittently is reliable timekeeping. State-of-the-art low-power real-time clocks suffer from long start-up times (order of seconds) and have low timekeeping granularity (tens of milliseconds at best), often not matching timing requirements of devices that experience numerous power outages per second. Our key insight is that time can be inferred by measuring alternative physical phenomena, like the discharge of a simple RC circuit, and that timekeeping energy cost and accuracy can be modulated depending on the run-time requirements. We achieve these goals with a multi-tier timekeeping architecture, named Cascaded Hierarchical Remanence Timekeeper (CHRT), featuring an array of different RC circuits to be used for dynamic timekeeping requirements. The CHRT and its accompanying software interface are embedded into a fresh batteryless wireless sensing platform, called Botoks, capable of tracking time across power failures. Low start-up time (max 5 ms), high resolution (up to 1 ms) and run-time reconfigurability are the key features of our timekeeping platform. We developed two time-sensitive batteryless applications to demonstrate the approach: a bicycle analytics tool, where the CHRT is used to track time between revolutions of a bicycle wheel, and wireless communication, where the CHRT enables radio synchronization between two intermittently-powered sensors.