Abstract

ECHOES is a novel System-On-a-Chip designed for ultra-low-power, high-performance frequency domain processing required in demanding IoT applications like audio and radar. It integrates a specialized RISC-V core with DSP extensions and a dedicated FFT hardware accelerator, achieving peak efficiency up to 199.8 GOPS/W for frequency-domain tasks. Notably, ECHOES is the first open-source SoC to feature an autonomous I/O engine supporting full-duplex Time Division Multiplexing (TDM) over I2S, allowing flexible data acquisition from up to 16 microphone or sensor inputs.

Report

Structured Report: Echoes SoC Analysis

Key Highlights

• High Efficiency: The FFT hardware accelerator achieves a remarkable peak energy efficiency of 199.8 GOPS/W.
• Performance Gain: The hardware FFT accelerator provides up to a 41.1x performance increase and an 11.2x efficiency improvement over software implementation.
• Core Architecture: Based on a RISC-V core enhanced with both fixed and floating-point Digital Signal Processing (DSP) extensions.
• Unique I/O Capability: It is the first open-source SoC offering an I/O engine with full-duplex Time Division Multiplexing (TDM) DSP mode over I2S, enabling simultaneous communication with up to 16 I/O devices (e.g., microphone arrays).
• Target Domain: Optimized for frequency-domain applications in low-power end-nodes, including audio processing, radar sensing, and Structural Health Monitoring (SHM).

Technical Details

• Fabrication Technology: 65nm CMOS process.
• Processor Components: Includes a RISC-V core, custom fixed/floating-point DSP extensions, and a dedicated Fast-Fourier Transform (FFT) hardware accelerator.
• FFT Performance: Achieves peak performance of 10.16 GOPS.
• General DSP Performance: Reaches 0.16 GFLOPS peak performance and 9.68 GFLOPS/W peak energy efficiency on general DSP kernels.
• Data Acquisition Support: Features an autonomous I/O engine designed to support ultra-low-power peripherals such as MEMS, digital microphones (via I2S), and ultra-low-power radars.
• I2S Protocol Mode: The full-duplex TDM DSP mode allows for high-density sensor interfacing, crucial for large microphone or sensor arrays.

Implications

• Validation of RISC-V Customization: ECHOES demonstrates the power of extending the RISC-V architecture with highly specialized hardware accelerators (like the FFT core) to meet stringent domain-specific performance and power requirements in the embedded space.
• Accelerating Edge AI/IoT: The exceptional energy efficiency (200 GOPS/W) makes complex frequency-domain signal processing (e.g., beamforming, spectral analysis) viable for battery-operated IoT end-nodes, pushing near-sensor analytics capabilities significantly further.
• Open Hardware Standard Setting: By being the first open-source SoC to implement advanced I2S TDM features for 16 simultaneous devices, ECHOES sets a new benchmark for flexible, high-channel-count audio/sensor data acquisition in the open-source hardware ecosystem.
• Democratization of DSP: The open-source nature of the SoC, coupled with powerful integrated DSP capabilities, lowers the barrier to entry for developing complex audio, radar, and sensing products.