  Particle physics detectors increasingly make use of custom FPGA firmware and
application-specific integrated circuits (ASICs) for data readout and
triggering. As these designs become more complex, it is important to ensure
that they are simulated under realistic operating conditions before beginning
fabrication. One tool to assist with the development of such designs is cocotb,
an open source digital logic verification framework. Using cocotb, verification
can be done at high level using the Python programming language, allowing
sophisticated data flow simulations to be conducted and issues to be identified
early in the design phase. Cocotb was used successfully in the development of a
testbench for several custom ASICs for the ATLAS ITk Strips detector, which
found and resolved many problems during the development of the chips.
