What are the contents of an nvSRAM device when it is shipped? Can I assume that the data is fixed?
Cypress ships nvSRAM devices with nonvolatile cells that are programmed to 0x00. However, incoming inspection routines at customer or contract manufacturer sites often reprogram these values to repeating patterns of 0xAA, 0x55, 0x00, 0xFF, 0xA5, and 0x5A.
Do not assume that the nvSRAM is in a set programmed state. If your system routines use the nvSRAM contents to determine first-time system configuration and cold or warm boot status, you must always program a complex 4-byte pattern (for example, 0x46, 0xE6, 0x49, 0x53) as part of the final system manufacturing test.