FRAM Contents when Shipped from Cypress - KBA88164

Version: *A

 

Question:

Are FRAM contents programmed when shipped from Cypress?

 

Answer:

Cypress ships F-RAM devices with 0x00. However, inspection routines at customer or contract manufacturer sites often reprogram these values to a known repeating patterns of 0xAA, 0x55, 0x00, 0xFF, 0xA5, and 0x5A. Do not assume that the F-RAM is in a set programmed state. If your system routines use the F-RAM contents to determine first-time system configuration and cold or warm boot status, you must always program a complex 4-byte pattern (such as 0x46, 0xE6, 0x49, and 0x53) as part of the final system manufacturing test.