Automatic Compiler Based FPGA Accelerator for CNN Training

Training of convolutional neural networks (CNNs) on embedded platforms to support on-device learning is earning vital importance in recent days. Designing flexible training hardware is much more challenging than inference hardware, due to design complexity and large computation/memory requirement. In this work, we present an automatic compiler based FPGA accelerator with 16-bit fixed-point precision for complete CNN training, including Forward Pass (FP), Backward Pass (BP) and Weight Update (WU). We implemented an optimized RTL library to perform training-specific tasks and developed an RTL compiler to automatically generate FPGA-synthesizable RTL based on user-defined constraints. We present a new cyclic weight storage/access scheme for on-chip BRAM and off-chip DRAM to efficiently implement non-transpose and transpose operations during FP and BP phases, respectively. Representative CNNs for CIFAR-10 dataset are implemented and trained on Intel Stratix 10 GX FPGA using proposed hardware architecture, demonstrating up to 479 GOPS performance.