Serial command port method, circuit, and system including main and command clock generators to filter signals of less than a predetermined duration

摘要

A serial command port for a flash memory device, such as an erasable programmable read-only memory (EPROM) or an electrically erasable programmable read-only memory (EEPROM), is disclosed. A main clock generator circuit is used to filter external signals. The main clock generator circuit generates a main clock signal when the external signals have been asserted for a predetermined amount of time. The command port receives commands via a data bus, and a command clock generator generates a command clock signal in response to the main clock signal to latch commands from the data bus into a command register. The command register is coupled to send each command to a command decode logic circuit to be decoded. A state clock generator generates a state clock signal following the main clock signal such that a state latch and logic circuit coupled to the command decode logic circuit changes state in response to the decoded command. Control circuitry is coupled to the state latch and logic circuit to generate signals to effect the change of state.