NanoController: A Minimal and Flexible Processor Architecture for Ultra-Low-Power Always-On System State Controllers

Abstract

Distributed nodes in IoT and wireless sensor networks, which are powered by small batteries or energy harvesting, are constrained to very limited energy budgets. By intelligent power management and power gating strategies for the main microcontroller of the system, the energy efficiency can be significantly increased. However, timer-based, periodical power-up sequences are too inflexible to implement these strategies, and the use of a programmable power management controller demands minimum area and ultra-low power consumption from this system part itself. In this paper, the NanoController processor architecture is proposed, which is intended to be used as a flexible system state controller in the always-on domain of smart devices. The NanoController features a compact ISA, minimal silicon area and power consumption, and enables the implementation of efficient power management strategies in comparison to much simpler and constrained always-on timer circuits. For a power management control application of an electronic door lock, the NanoController is compared to small state-of-the-art controller architectures and has up to 86% smaller code size and up to 92% less silicon area and power consumption for 65 nm standard cell ASIC implementations.