A Convolutional Spiking Neural Network Accelerator with the Sparsity-aware Memory and Compressed Weights

The spiking neural network (SNN) has advantage in the edge AI applications for its spatiotemporal sparsity. The high energy efficiency is an important concern in the study of SNN accelerator designs. In this paper, a lightweight event-driven convolutional SNN accelerator that utilizes the sparsity of both the spike events and the network weights is proposed. In the event-driven mode, the proposed accelerator uses the compressed input spikes and a spike-oriented convolution data flow. An output spike compressor is also designed. To balance the computation performance and the memory space occupancy, a spike sparsity-aware memory scheme that automatically switches the spike format by a real-time monitoring strategy is designed. The compression memories and a buffer for network weights are designed to save the on-chip memory space. The accelerator prototype is verified on the Xilinx Virtex XCVU9P FPGA platform. It achieves an equivalent performance of 139.5GFLOPS on the N-MNIST dataset. Compared to the baseline using the same computational resources, the proposed accelerator can improve the inference performance, the inference energy efficiency and the memory space by 4.6, 3.6 and 1.6 times, respectively. The proposed accelerator has advantages in energy efficiency and hardware overhead compared to the previous works on the same hardware platform.