Emerging applications in the IoT domain require ultra-low-power and high-performance end-nodes to deal with complex near-sensor-data analytics. Domains such as audio, radar, and Structural Health Monitoring require many computations to be performed in the frequency domain rather than in the time domain. We present ECHOES, a System-On-a-Chip (SoC) composed of a RISC-V core enhanced with fixed and floating-point digital signal processing (DSP) extensions and a Fast-Fourier Transform (FFT) hardware accelerator targeting emerging frequency-domain application. The proposed SoC features an autonomous I/O engine supporting a wide set of peripherals, including Ultra-Low-Power radars, MEMS, and digital microphones over I2S protocol with full-duplex Time Division Multiplexing DSP mode, making ECHOES the first open-source SoC which offers this functionality enabling simultaneous communication with up to 16 I/Os devices. ECHOES, fabricated with 65nm CMOS technology, reaches a peak performance of 0.16 GFLOPS and a peak energy efficiency of 9.68 GFLOPS/W on a wide range of floating and fixed-point general-purpose DSP kernels. The FFT accelerator achieves performance up to 10.16 GOPS with an efficiency of 199.8 GOPS/W, improving performance and efficiency by up to 41.1x and 11.2x, respectively, over its software implementation of this critical task for frequency domain processing.

翻译：物联网领域新兴应用要求超低功耗、高性能终端节点处理复杂的近传感器数据分析。音频、雷达及结构健康监测等场景需要在频域而非时域执行大量计算。本文提出ECHOES——一款系统级芯片（SoC），其核心为增强型RISC-V处理器，集成定点与浮点数字信号处理（DSP）扩展及快速傅里叶变换（FFT）硬件加速器，专为新兴频域应用设计。该SoC配备自主I/O引擎，支持包括超低功耗雷达、MEMS传感器及基于I2S协议的数字麦克风（具备全双工时隙复用DSP模式）在内的丰富外设接口，使ECHOES成为首款提供此功能并支持同时与多达16个I/O设备通信的开源SoC。基于65nm CMOS工艺制造的ECHOES，在通用浮点/定点DSP内核运算中峰值性能达0.16 GFLOPS，峰值能效达9.68 GFLOPS/W。其FFT加速器性能最高可达10.16 GOPS，能效为199.8 GOPS/W，相较该频域处理关键任务的软件实现方案，性能与能效分别提升达41.1倍和11.2倍。