  This paper presents a spiking neural network (SNN) accelerator made using
fully open-source EDA tools, process design kit (PDK), and memory macros
synthesized using OpenRAM. The chip is taped out in the 130 nm SkyWater process
and integrates over 1 million synaptic weights, and offers a reprogrammable
architecture. It operates at a clock speed of 40 MHz, a supply of 1.8 V, uses a
PicoRV32 core for control, and occupies an area of 33.3 mm^2. The throughput of
the accelerator is 48,262 images per second with a wallclock time of 20.72 us,
at 56.8 GOPS/W. The spiking neurons use hysteresis to provide an adaptive
threshold (i.e., a Schmitt trigger) which can reduce state instability. This
results in high performing SNNs across a range of benchmarks that remain
competitive with state-of-the-art, full precision SNNs. The design is open
sourced and available online: https://github.com/sfmth/OpenSpike
