We employ Cypress flash device P/N S29JL032J70TFI310 in our product design. There is application code residing in the bottom-most sector SA0 (0x0000) of the subject device that needs to be protected from inadvertent erasure.
Per the attached Cypress datasheet 002-00857 Rev. *J, paragraph 8.10 (page 22), I can do an in-system sector protect of any flash sector such as SA0. Implementing this algorithm as depicted in Figure 2. In-System Sector Protect/Unprotect Algorithms (page 24), it appears to be successfully performed as signified by a data value “01h” <Data = 01h?> when any byte location within the boot sector is read back. However after protecting the boot sector per the algorithm, when I subsequently execute a chip erase command the boot sector is erased with all other sectors.
Is that correct device operation or am I incorrectly implementing or interpreting the sector protect algorithm? In other words, does the in-system sector protect pertain only to the individual sectors and will not protect those sectors from an inadvertent chip erase command?
Could you please double check the voltage on RESET# pin while executing sector protection command sequence and sector erase command sequence? Voltage on RESET# pin should be VID during sector protection and VIH during sector erase.
Thanks and Regards,