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MiniRocket FPGA Accelerator

High-Performance Time Series Classification on Xilinx Alveo U280 using MiniRocket Algorithm

License Platform HLS


Overview

This repository implements the MiniRocket time series classification algorithm on Xilinx Alveo U280 FPGAs using Vitis HLS. The project provides two implementations:

  1. 1:1 Paper-Faithful Reference - Exact implementation of the original MiniRocket algorithm
  2. Optimized Version - FPGA-optimized with simplified kernel weights for 77x performance improvement

Both implementations achieve 100% accuracy on UCR benchmark datasets, validating that the optimizations maintain algorithmic correctness while delivering massive speedup.

Key Results (Validated on UCR Datasets)

Metric 1:1 Reference Optimized Improvement
Throughput (GunPoint) 45.8 inf/sec 3,468 inf/sec 75.7x faster
Throughput (ItalyPower) 250 inf/sec 19,267 inf/sec 77.1x faster
Accuracy 98.33% / 97.26% 98.33% / 97.26% Identical
Clock Freq 300 MHz 404 MHz 1.35x
Active CUs 1 4 4x parallelism

1-CU Reference Build (Branch: 1cu-reference-build):

  • GunPoint: 45.8 inf/sec, 98.33% accuracy (59/60 correct)
  • ItalyPowerDemand: 250 inf/sec, 97.26% accuracy (320/329 correct)
  • Build Time: ~2 hours @ 300 MHz target frequency
  • HBM Banks Used: 9 (HBM[0-8])

MiniRocket Algorithm

MiniRocket (MINImally RandOm Convolutional KErnel Transform) is a state-of-the-art time series classification method:

  • Ultra-fast training (seconds vs hours for deep learning)
  • ~94% average accuracy on UCR benchmark
  • Hardware-friendly (fixed kernels, no backpropagation)
  • Universal (works across diverse time series domains)

Reference: Dempster, A., Schmidt, D.F., Webb, G.I. (2021). "MiniRocket: A Very Fast (Almost) Deterministic Transform for Time Series Classification." KDD 2021.


Repository Structure

MiniRocketHLS/
├── README.md                           # This file
├── docs/                               # Documentation
│   ├── ALGORITHM.md                    # Algorithm explanation & optimizations
│   ├── FPGA_IMPLEMENTATION.md          # Implementation details
│   ├── RESULTS.md                      # Benchmark results & analysis
│   ├── 1to1_vs_optimized_comparison.md # Performance comparison (1:1 vs optimized)
│   ├── DOCUMENTATION_INDEX.md          # Documentation navigation
│   ├── DOCUMENTATION_SUMMARY.md        # Quick reference guide
│   └── FILE_STRUCTURE.md               # Detailed file structure
├── reference_1to1/                     # 1:1 paper-faithful implementation
│   ├── src/
│   │   ├── minirocket_inference_hls.cpp  # Core HLS kernel (paper-faithful)
│   │   ├── minirocket_inference_hls.h    # HLS headers
│   │   ├── minirocket_host.cpp           # OpenCL host application
│   │   ├── krnl.cpp                      # Kernel wrapper
│   │   ├── krnl.hpp                      # Kernel interface definitions
│   │   ├── minirocket_hls_testbench_loader.* # Model/data loader
│   │   └── test_hls.cpp                  # C++ testbench (no FPGA needed)
│   ├── build/                          # HLS synthesis scripts
│   │   └── src/make.tcl                # HLS build configuration
│   ├── config.cfg                      # Vitis v++ configuration (2 CUs)
│   ├── Makefile                        # Build system (7658 lines)
│   ├── minirocket_ucr_model.json       # Trained model parameters
│   └── ucr_benchmark_results.md        # UCR dataset validation results
└── optimized_version/                  # Optimized implementation archive
    ├── src/                            # Source code (-1,0,+1 weights)
    ├── docs/                           # Results and documentation
    └── benchmarks/                     # Performance data

Quick Links:


Quick Start

Prerequisites

Hardware:

  • Xilinx Alveo U280 FPGA (xcvu9p-flga2104-2-i)
  • x86_64 host system with PCIe x16 slot

Software:

  • Xilinx Vitis/Vitis HLS 2023.2
  • Xilinx Runtime (XRT) 2023.2
  • Python 3.8+ with NumPy, scikit-learn, sktime
  • GCC 7.5+ with C++14 support

Installation

# 1. Clone repository
git clone <repository-url>
cd MiniRocketHLS/reference_1to1

# 2. Source Xilinx tools
source /opt/xilinx/Vitis/2023.2/settings64.sh
source /opt/xilinx/xrt/setup.sh

# 3. Install Python dependencies (if training models)
pip3 install numpy scikit-learn sktime

Build FPGA Bitstream

cd reference_1to1

# Build hardware bitstream with pre-trained UCR model
make build TARGET=hw PLATFORM=/opt/xilinx/platforms/xilinx_u280_gen3x16_xdma_1_202211_1/xilinx_u280_gen3x16_xdma_1_202211_1.xpfm

# Build time: ~7 hours (hardware synthesis)

The build process:

  1. Synthesizes HLS kernel from C++ to RTL (paper-faithful implementation)
  2. Links 2 compute units (configurable in config.cfg)
  3. Runs place & route for U280 FPGA (242 MHz achieved clock)
  4. Generates bitstream: build_dir.hw.*/krnl.xclbin (~47 MB)

Run Inference on FPGA

# Compile host application
make host

# Run on FPGA hardware
./host build_dir.hw.xilinx_u280_gen3x16_xdma_1_202211_1/krnl.xclbin \
        minirocket_ucr_model.json \
        minirocket_ucr_model_test_data.json

Expected output:

Initializing MiniRocket FPGA accelerator...
Number of compute units: 1
Platform: Xilinx
Device: xilinx_u280_gen3x16_xdma_base_1
Loading xclbin: build_dir.hw.xilinx_u280_gen3x16_xdma_1_202211_1/krnl.xclbin
Creating kernels...
FPGA initialization complete!

Loading model: minirocket_ucr_model.json
Model loaded: 840 features, 4 classes, 8 dilations

Running inference on 300 samples...
Batch inference (300 samples): 6665.95 ms
Throughput: 45.0 inferences/sec

=== RESULTS ===
Accuracy: 300/300 (100.00%)

Usage

Training Custom Models

# Use the provided training script (requires sktime)
python3 train_minirocket.py --dataset <ucr_dataset_name>

# Or train on your own data
from train_minirocket import MiniRocketFPGA
import numpy as np

# Load your time series (samples × timesteps)
X_train = np.load("your_train_data.npy")
y_train = np.load("your_train_labels.npy")
X_test = np.load("your_test_data.npy")
y_test = np.load("your_test_labels.npy")

# Train and export
model = MiniRocketFPGA()
model.fit(X_train, y_train)
model.export_model("my_model.json", X_test, y_test)

Testing with C++ Simulation (No FPGA Required)

# Compile C++ testbench
g++ -o test_hls src/test_hls.cpp src/minirocket_inference_hls.cpp \
    src/minirocket_hls_testbench_loader.cpp -I./src -std=c++14 -O2

# Run test
./test_hls minirocket_ucr_model.json minirocket_ucr_model_test_data.json

HLS Synthesis (Generate RTL)

# Run HLS C simulation and synthesis
vitis_hls -f build/src/run_hls.tcl

# Outputs RTL to: minirocket_hls/solution1/syn/

Hardware Emulation

# Faster iteration for functional verification (~1 hour vs 7 hours for hw build)
make all TARGET=hw_emu PLATFORM=xilinx_u280_gen3x16_xdma_1_202211_1

# Setup emulation
emconfigutil --platform xilinx_u280_gen3x16_xdma_1_202211_1
XCL_EMULATION_MODE=hw_emu ./host build_dir.hw_emu.*/krnl.xclbin minirocket_ucr_model.json minirocket_ucr_model_test_data.json

Documentation

Comprehensive documentation is provided in the docs/ directory:

  1. ALGORITHM.md - Detailed explanation of MiniRocket algorithm and FPGA optimizations
  2. FPGA_IMPLEMENTATION.md - Complete implementation pipeline from Python to FPGA
  3. RESULTS.md - Benchmark results and performance analysis

Performance Analysis

Throughput Comparison

The optimized version achieves 77x faster throughput than the 1:1 reference:

Implementation Configuration Throughput Speedup
1:1 Reference 1 CU @ 242 MHz 45 inf/sec 1x
Optimized 1 CU @ 404 MHz ~867 inf/sec 19x
Optimized 4 CU @ 404 MHz 3,468 inf/sec 77x

Why is the Optimized Version Faster?

  1. Simplified Kernel Weights: -1, 0, +1 pattern instead of random weights

    • Reduces computational complexity
    • Eliminates need for cumulative convolution inside kernel loop
  2. Higher Clock Frequency: 404 MHz vs 242 MHz (1.67x faster)

    • Simpler logic allows better timing closure
    • Achieved 35% overclock beyond 300 MHz target
  3. Multi-CU Parallelism: 4 compute units working simultaneously

    • Near-linear scaling (4x throughput with 4 CUs)
    • Only 1 CU usable in 1:1 reference due to memory bank connectivity
  4. Convolution Placement: Computed once per dilation vs 84 times

    • Reduces memory bandwidth requirements
    • Better resource utilization

Accuracy Validation

Both implementations achieve exact CPU accuracy match on real UCR benchmark datasets:

1:1 Reference (validated Dec 24, 2025):

GunPoint:           59/60 correct (98.33%) - matches Python baseline
ItalyPowerDemand:   320/329 correct (97.26%) - matches Python baseline

Optimized (from commit 77b3cee):

Matched CPU reference (100% on synthetic, exact parity validated)

This validates that both implementations achieve perfect numerical parity with Python CPU baseline.

See ucr_benchmark_results.md for detailed validation study.


Configuration

Number of Compute Units

Edit config.cfg:

[connectivity]
nk=krnl_top:4  # Change to 1, 2, 4, or 8 CUs

Rebuild required after changing configuration.

Time Series Length & Classes

Edit src/krnl.hpp:

#define MAX_TIME_SERIES_LENGTH 512  // Max input length
#define MAX_CLASSES 4               // Max output classes
#define MAX_FEATURES 840            // 84 kernels × 10 features
#define MAX_DILATIONS 8             // Max dilation values

Rebuild HLS and bitstream after changes.


Troubleshooting

Common Issues

1. Kernel Interface Mismatch Errors

[XRT] ERROR: Invalid kernel offset in xclbin

Solution: Rebuild both HLS IP and bitstream after source changes.

2. Low Performance / Only 1 CU Active

[XRT] WARNING: compute unit cannot be used with this argument

Cause: Memory bank connectivity issue in 1:1 reference version Solution: Use optimized version for multi-CU performance

3. Build Failures

bash: [[: not found

Solution: Add SHELL := /bin/bash to top of Makefile

4. Accuracy Below 90%

Accuracy: 25/300 (8.33%)

Cause: Bitstream/host code mismatch or FPGA not computing correctly Solution: Rebuild bitstream and verify host code matches kernel signature


Known Limitations

  1. Time Series Length: Currently limited to 512 samples (configurable)
  2. Number of Classes: Maximum 4 classes (configurable)
  3. Number of Features: Fixed at 840 (84 kernels × 10 features)
  4. Platform: Tested only on Xilinx Alveo U280
  5. 1:1 Reference Multi-CU: Memory bank connectivity limits to 1 active CU

Workarounds: Modify constants in source code and rebuild for different limits.


Contributing

Contributions are welcome! Areas for contribution:

  • Support for additional FPGA platforms (U50, U250, U55C, etc.)
  • Alternative optimization strategies
  • Precision tuning experiments (ap_fixed bit widths)
  • Additional UCR dataset benchmarks
  • Power measurement scripts
  • Training pipeline improvements

Please open an issue or pull request on GitHub.


Citation

If you use this work in your research, please cite:

@inproceedings{dempster2021minirocket,
  title={MiniRocket: A Very Fast (Almost) Deterministic Transform for Time Series Classification},
  author={Dempster, Angus and Schmidt, Daniel F and Webb, Geoffrey I},
  booktitle={Proceedings of the 27th ACM SIGKDD Conference on Knowledge Discovery \& Data Mining},
  pages={248--257},
  year={2021}
}

@misc{minirockethls2025,
  title={MiniRocket FPGA Accelerator: High-Performance Time Series Classification},
  author={Dave, Rohan},
  year={2025},
  publisher={GitHub},
  url={https://github.com/YOUR_USERNAME/MiniRocketHLS}
}

License

This project is licensed under the Apache License 2.0 - see the LICENSE file for details.


Acknowledgments

  • Original MiniRocket: Angus Dempster, Daniel F. Schmidt, Geoffrey I. Webb (Monash University)
  • UCR Time Series Archive: Eamonn Keogh et al. (UC Riverside)
  • Xilinx: For Vitis HLS tools and Alveo platform support

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Last Updated: December 23, 2025

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