Question: The Sector Protection Status I read from ID-CFI ASO in GL-S is not consistent with the status indicated by PPB and DYB. How can I correctly read Sector Protection Status from ID-CFI ASO?
Answer: The Sector Protection State of GL-S and GL-T flash families is determined by the combination of Persistent Protection Bit (PPB) and Dynamic Protection Bit (DYB). The sector is protected when either the related PPB or DYB is set to 0, or both are set to 0. The sector is unprotected when both the related PPB and DYB are set to 1.
Other than checking the combination of the related PPB and DYB, GL-S and GL-T flash families also provide an easier way to check Sector Protection Status. ID-CFI Location 02h indicates Sector Protection Status for the sector selected by the sector address (SA) used in the ID-CFI enter command. If the data at ID-CFI location 02h is 1, it indicates the sector is protected. If the data is 0, the sector is unprotected.
To correctly read Sector Protection Status from ID-CFI, the following requirements should be satisfied:
- The access time to read ID-CFI location 02h is always tACC.
- Read of ID-CFI location 02h requires CE# to go High before the read and return Low to initiate the read (asynchronous read access).
- Page mode read between ID-CFI location 02h and other ID-CFI locations is not supported.
- To read the protection status of more than one sector, it requires to exit the ID-CFI ASO and enter the ID-CFI ASO again using the new SA of the sector to be checked.