37.14.2 Frozen Mode

When the external device asserts the NWAIT signal (active low), and after an internal synchronization of this signal, the SMC state is frozen, i.e., SMC internal counters are frozen, and all control signals remain unchanged. When the resynchronized NWAIT signal is deasserted, the SMC completes the access, resuming the access from the point where it was stopped. See the figure below. This mode must be selected when the external device uses the NWAIT signal to delay the access and to freeze the SMC.

The assertion of the NWAIT signal outside the expected period is ignored as illustrated in the figure Read Access with NWAIT Assertion in Frozen Mode (EXNW_MODE = 10).