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Key Phrase Recognition for Low-Power FPGA Devices_Use case

Key Phrase Recognition for Low-Power FPGA Devices

AT A GLANCE

Domain

Semiconductors, Consumer Electronics, Industrial IoT, Automotive, Home Automation

Challenge

Enable always-on voice recognition on low-power FPGA devices while working within strict power, memory, and compute constraints. Maintaining continuous listening without draining system resources was critical for edge and embedded applications.

Solution

A custom lightweight neural network for key phrase recognition, delivered as a pre-trained, fully documented reference model with training pipelines, deployment steps, and a live demonstration on the Lattice iCE40 FPGA.

Platform

Lattice iCE40 FPGA, Lattice sensAI, TensorFlow, Python, C++, Ubuntu/Linux

Executive Summary

A leading U.S.-based semiconductor company specializing in low-power FPGAs partnered with MosChip to design a custom neural network for key phrase recognition, drawing on ours edge AI development services. The goal was a reference model that customers could use as a foundation to build and deploy AI-powered, always-on voice control on their own FPGA devices.

MosChip designed, trained, and deployed the model on the Lattice iCE40 FPGA, keeping this edge AI solution lightweight, power-efficient, and reusable across applications. Alongside the model, MosChip delivered full documentation, training pipelines, deployment steps, and binary creation workflows, so customers could adopt, customize, and scale their own voice-enabled solutions without deep FPGA or neural network expertise.

THE RESULT

The outcome is a ready-to-use, pre-trained model and a robust reference framework that helps businesses across computing. Consumer electronics, automotive, and home automation accelerate AI adoption with FPGA-based, voice-enabled systems.

The Challenge

Bringing AI-powered voice recognition to low-power FPGAs meant tackling four problems at once, each of which slowed customers down in a different way:

  • Rapid evolution of FPGA hardware: New FPGA boards and toolchain updates arrive every year with different capabilities. Without a stable baseline for deploying AI models, customers faced longer development cycles, fragmented solutions, and missed opportunities to use the latest features.
  • Constraints of low-power devices: Not every neural network can be mapped onto resource-constrained FPGAs such as the iCE40 family. Popular architectures often exceeded the available memory, compute, and power budget, leaving a gap between what AI could do and what ultra-low-power hardware could support.
  • No reference models or frameworks: Without pre-trained models or example designs, customers had to build from scratch. That meant steep learning curves, higher costs, inconsistent performance, and slower time to market.
  • A steep learning curve for AI on FPGA: Deploying AI on an FPGA spans neural networks, hardware mapping, compiler flows, and binary creation. Many customers lacked expertise across all of these, which limited adoption to advanced developers.

Addressing these challenges requires more than just a compact AI model. Customers needed a validated framework that simplified model deployment, reduced development effort, and made AI on low-power FPGAs easier to adopt and scale.

The Solution

MosChip designed and developed a custom Key Phrase Recognition solution for low-power FPGA devices, enabling always-on voice recognition within limited power, memory, and processing resources. The solution provides a reusable foundation for voice-enabled applications and simplifies AI deployment on resource-constrained hardware. The engagement covered five areas:

  • Custom neural network architecture: A lightweight network designed around FPGA constraints such as limited DSP slices, memory bandwidth, and power budgets. It minimizes computational overhead while keeping high accuracy in detecting key phrases.
  • Comprehensive model development: The full lifecycle, from dataset preparation (cleaning, augmenting, and labelling voice samples) through training, fine-tuning, and evaluation across multiple datasets, to a deployment-ready pipeline. Customers can move from prototyping on general-purpose platforms to running on FPGA hardware without major rework.
  • FPGA deployment and demonstration: The trained model was quantized, compiled with the Lattice toolchain, and deployed on the Lattice iCE40 FPGA. In the working demo, voice command phrases such as “machine on” and “machine off” are recognized in real time to trigger corresponding actions, proving the approach for industrial, IoT, and consumer use.
  • Pre-trained and documented reference model: A pre-trained model with step-by-step documentation, reference pipelines, and deployment instructions. Customers can reuse it directly, retrain it with their own data, or extend it to support additional voice commands.
  • Validation and reporting: Functional testing and evaluation reports covering accuracy, latency, and FPGA resource utilization, giving customers confidence that the solution performs consistently across different FPGA environments.

Architecture

Voice data is used to train the key phrase model, which is converted with the Lattice compiler and TFLite converter into a quantized model. On the FPGA, the device listens continuously at low power, pre-processes incoming speech, runs the quantized model, and raises an alert when a key phrase is detected.

Key phrase recognition flow: from model training to on-device detection

Tools & Technologies

Componentspecification
Hardware PlatformLattice iCE40 FPGA, HiMax HM01B0 UPduino shield
AI FrameworksTensorFlow, cuDNN, Anaconda, TFLite conversion
FPGA ToolchainLattice Radiant v1.1, Lattice Radiant Programmer v1.1, Lattice sensAI Compiler v2.1
Programming LanguagesPython, C++
Operating SystemUbuntu/Linux
Deployment FormatQuantized model compiled to FPGA binary

Outcomes

By pairing a purpose-built, FPGA-optimized model with complete documentation and pipelines, MosChip gave the client something customers can build on well beyond a single use case.

  • Faster time to market, because pre-trained reference models and documentation let customers deploy voice-enabled solutions without starting from scratch.
  • Energy-efficient voice recognition that delivers accurate detection within tight power budgets, well suited to IoT and embedded devices.
  • Customizability and scalability, as customers can retrain or extend the reference model to add new phrases or adapt it to domain-specific uses.
  • Reduced risk through a working FPGA deployment that validated feasibility and increased confidence in large-scale adoption.
  • Better developer productivity, with detailed reports, pipelines, and ready-to-use models that shorten the learning curve for AI on FPGA platforms.

FAQ's

What is key phrase recognition, and where is it used?

Key phrase recognition detects specific spoken words or phrases, such as “machine on” or “machine off,” and triggers a defined action when one is heard. It powers always-on voice control in smart home devices, consumer electronics, industrial equipment, automotive systems, and IoT products, where a small, fast, power-efficient model is needed rather than full speech-to-text.

Why run voice recognition on a low-power FPGA instead of the cloud or a larger processor?

Running recognition directly on the device keeps latency low, avoids sending audio off the device, and works without a network connection. A low-power FPGA can listen continuously within a very small power budget, which makes it a good fit for battery-powered and always-on products.

Why can’t standard deep learning models run on small FPGAs?

Popular neural networks are typically designed for GPUs or powerful processors and require more memory, computing power, and energy than small FPGAs can provide. To run efficiently, models need to be purpose-built or optimized, then quantized and compiled to fit within the FPGA’s limited DSP, memory, and power resources.

How does a pre-trained reference model help customers adopt AI on FPGAs?

A pre-trained, documented reference model gives teams a working starting point. They can use it as-is, retrain it on their own voice data, or extend it to new phrases, instead of building the neural network, training pipeline, and deployment flow from scratch. This shortens the learning curve and reduces time to market.

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