BrainScaleS-2 — Heidelberg University

Learn about Heidelberg University's neuromorphic hardware: BrainScaleS-2

BrainScaleS-2 At A Glance

Release Year: 2022
Status: Released
Chip Type: Mixed-signal
Software: hxtorch, jaxsnn, PyNN.brainscales2, BrainScaleS-2 OS
Applications: Edge processing, robotics
Neurons: 512
Synapses: 131072
Weight bits: 6 bits (+ 6 bit mask for structural plasticity)
On-Chip Learning: true
Power: ~1 W

The BrainScaleS-2 is an accelerated spiking neuromorphic system-on-chip integrating 512 adaptive integrate-and-fire neurons, 131k plastic synapses, embedded processors, and event routing. It enables fast emulation of complex neural dynamics and exploration of synaptic plasticity rules. The architecture supports training of deep spiking and non-spiking neural networks using hybrid techniques like surrogate gradients.

The BrainScaleS-2 accelerated neuromorphic system is an integrated circuit architecture for emulating biologically-inspired spiking neural networks. It was developed by researchers at the Heidelberg University and collaborators. Key features of the BrainScaleS-2 system include:

System Architecture

  • Single-chip ASIC integrating a custom analog core with 512 neuron circuits, 131k plastic synapses, analog parameter storage, embedded processors for digital control and plasticity, and an event routing network
  • Processor cores run a software stack with a C++ compiler and support hybrid spiking and non-spiking neural network execution
  • Capable as a unit of scale for larger multi-chip or wafer-scale systems

Neural and Synapse Circuits

  • Implements the Adaptive Exponential Integrate-and-Fire (AdEx) neuron model with individually configurable model parameters
  • Supports advanced neuron features like multi-compartments and structured neurons
  • On-chip synapse correlation and plasticity measurement enable programmable spike-timing dependent plasticity

Hybrid Plasticity Processing

  • Digital control processors allow flexible implementation of plasticity rules bridging multiple timescales
  • Massively parallel readout of analog observables enables gradient-based and surrogate gradient optimization approaches

Applications and Experiments

  • Accelerated (1,000-fold compared to biological real time) emulation of complex spiking neural network dynamics, including configurable multi-compartmental cell morphologies
  • Exploration of synaptic plasticity models and critical network dynamics at biological timescales
  • Training of deep spiking neural networks using surrogate and exact gradient techniques
  • Non-spiking neural network execution leveraging synaptic crossbar for analog matrix multiplication

The accelerated operation and flexible architecture facilitate applications in computational neuroscience research and novel machine learning approaches. The system design serves as a scalable basis for future large-scale neuromorphic computing platforms.

DateTitleAuthorsVenue/Source
April 2024jaxsnn: Event-driven gradient estimation for analog neuromorphic hardwareEric Müller, Moritz Althaus, Elias Arnold, Philipp Spilger, Christian Pehle, Johannes Schemmel2024 Neuro-Inspired Computational Elements Conference (NICE)
April 2023hxtorch.snn: Machine-learning-inspired Spiking Neural Network Modeling on BrainScaleS-2Philipp Spilger, Elias Arnold, Luca Blessing, Christian Mauch, Christian Pehle, Eric Müller, Johannes Schemmel2023 Neuro-Inspired Computational Elements Conference (NICE)
May 2022A Scalable Approach to Modeling on Accelerated Neuromorphic HardwareEric Müller, Elias Arnold, Oliver Breitwieser, Milena Czierlinski, Arne Emmel, Jakob Kaiser, Christian Mauch, Sebastian Schmitt, Philipp Spilger, Raphael Stock, Yannik Stradmann, Johannes Weis, Andreas Baumbach, Sebastian Billaudelle, Benjamin Cramer, Falk Ebert, Julian Göltz, Joscha Ilmberger, Vitali Karasenko, Mitja Kleider, Aron Leibfried, Christian Pehle, Johannes SchemmelFrontiers in Neuroscience (Neuromorphic Engineering)
February 2022The BrainScaleS-2 accelerated neuromorphic system with hybrid plasticityChristian Pehle, Sebastian Billaudelle, Benjamin Cramer, Jakob Kaiser, Korbinian Schreiber, Yannik Stradmann, Johannes Weis, Aron Leibfried, Eric Müller, Johannes SchemmelFrontiers in Neuroscience (Neuromorphic Engineering)
January 2021hxtorch: PyTorch for BrainScaleS-2 — Perceptrons on Analog Neuromorphic HardwarePhilipp Spilger, Eric Müller, Arne Emmel, Aron Leibfried, Christian Mauch, Christian Pehle, Johannes Weis, Oliver Breitwieser, Sebastian Billaudelle, Sebastian Schmitt, Timo C. Wunderlich, Yannik Stradmann, Johannes Schemmel2020 International Workshop on IoT, Edge, and Mobile for Embedded Machine Learning (ITEM)

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