What is the standard hardware solution to safely pass a single-bit signal from a slow clock domain to a fast clock domain?
A two flip-flop synchronizer is the standard solution for single-bit CDC. The first flip-flop may go metastable, but the second flip-flop samples it after one full clock period — giving enough time for the metastability to resolve in the vast majority of cases.
Direct connections create metastability risk. Level shifters handle voltage differences, not timing. Inverter chains are not a synchronization solution.
