Versatile Internet of Things (IoT) applications call for re-configurable IoT devices that can easily extend new functionality on demand. However, the heterogeneity of functional chips brings difficulties in device customization, leading to inadequate flexibility. In this paper, we propose LEGO, a novel architecture for chip-level reconfigurable IoT devices that supports plug-and-play with Commercial Off-The-Shelf (COTS) chips. To combat the heterogeneity of functional chips, we first design a novel Unified Chip Description Language (UCDL) with meta-operation and chip specifications to access various types of functional chips uniformly. To achieve chips plug-and-play, we build up a novel platform that shifts all chip control logic to a centralized gateway to make IoT devices completely decoupled from specific applications, which does not need to make any changes when plugging in new functional chips. We also built up a three-layer orchestration architecture for gateway instructions, which minimizes communication overheads in centralized chip control. We implement the prototype and conduct extensive evaluations with 100+ types of COTS functional chips. The results show that new functional chips can be automatically
accessed by the system within 0.13 seconds after being plugged in with only 0.53 kb of data transmission on average, demonstrating the efficacy of LEGO design.

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