Document Number: 001-98285 Rev. *R
Page 31 of 108
S29GL01GS/S29GL512S
S29GL256S/S29GL128S
5.4.6
ASO Entry and Exit
5.4.6.1
ID-CFI ASO
The system can access the ID-CFI ASO by issuing the ID-CFI Entry command sequence during Read Mode. This entry command
uses the Sector Address (SA) in the command to determine which sector will be overlaid and which sector's protection state is
reported in word location 2h. See the detail description
.
The ID-CFI ASO allows the following activities:
Read ID-CFI ASO, using the same SA as used in the entry command.
Read Sector Protection State at Sector Address (SA) + 2h. Location 2h provides volatile information on the current state of
sector protection for the sector addressed. Bit 0 of the word at location 2h shows the logical NAND of the PPB and DYB bits
related to the addressed sector such that if the sector is protected by either the PPB=0 or the DYB=0 bit for that sector the
state shown is protected. (1= Sector protected, 0= Sector unprotected). This protection state is shown only for the SA
selected when entering ID-CFI ASO. Reading other SA provides undefined data. To read a different SA protection state
ASO exit command must be used and then enter ID-CFI ASO again with the new SA.
ASO Exit.
The following is a C source code example of using the CFI Entry and Exit functions. Refer to the
Cypress Low Level Driver User's
Guide
(available on
) for general information on Cypress flash memory software development guidelines.
/* Example: CFI Entry command */
*( (UINT16 *)bas 0x55 ) = 0x0098; /* write CFI entry command */
/* Example: CFI Exit command */
*( (UINT16 *)bas 0x000 ) = 0x00F0; /* write cfi exit command */
5.4.6.2
Status Register ASO
The Status Register ASO contains a single word of registered volatile status for Embedded Algorithms. When the Status Register
read command is issued, the current status is captured (by the rising edge of WE#) into the register and the ASO is entered. The
Status Register content appears on all word locations. The first read access exits the Status Register ASO (with the rising edge of
CE# or OE#) and returns to the address space map in use when the Status Register read command was issued. Write commands
will not exit the Status Register ASO state.
5.4.6.3
Secure Silicon Region ASO
The system can access the Secure Silicon Region by issuing the Secure Silicon Region Entry command sequence during Read
Mode. This entry command uses the Sector Address (SA) in the command to determine which sector will be overlaid.
The Secure Silicon Region ASO allows the following activities:
Read Secure Silicon Regions.
Programming the customer Secure Silicon Region is allowed using the Word or Write Buffer Programming commands.
ASO Exit using legacy Secure Silicon Exit command for backward software compatibility.
ASO Exit using the common exit command for all ASO - alternative for a consistent exit method.
