SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
NOR flash architecture, introduced in 1988, is a flash technology. Unlike NAND, which is a sequential access device, NOR is directly addressable; that is, it is designed to be a random access device. NOR is best suited to devices used to store and run code or firmware, usually in small capacities. While NOR has fast read capabilities, it also has slow write and erase functions when compared to the NAND architecture.
Table 12-4156 summarizes the level of the NOR interface signals applied to external devices or memories.
Bus Operation | CLK | nADV | nCS | nOE | nWE | WAIT | DQ[15-0] |
---|---|---|---|---|---|---|---|
Read (asynchronous) | x | L | L | L | H | Asserted | Output |
Read (synchronous) | Running | L | L | L | H | Driven | Output |
Read (burst suspend) | Halted | x | L | H | H | Active | Output |
Write | x | L | L | H | L | Asserted | Input |
Output disable | x | x | L | H | H | Asserted | High-Z |
Standby | x | x | H | x | x | High-Z | High-Z |