Knowledge of clocking aids ASIC-emulator choice

摘要

Originally, ASIC emulators used simple clocking-the target system supplied it. However, as custom-processor-based emulators emerged and manufacturers added multiplexed I/O capabilities to increase the efficiency of FPGA-based machines, the methods of internal and external clocking for emulation systems became quite complex and confusing, Learning how to categorize the various clock methods and how the methods work can clear up some of this mystery. Once you know the pros and cons of each method, you can make a more informed decision when choosing an emulator. Emulators divide into three categories: those that exhibit pure event behavior, those that exhibit pure cycle behavior, and hybrids. Each category handles various target-system clock situations, single-clock-domain environments, and environments that contains multiple, asynchronous clocks. By understanding how the categories manage these conditions, you can determine each method's advantages and disadvantages.