Is it necessary to set the address bit A26 to 1 while sending commands to access second die of S70GL02GS?
Yes, it is necessary to set the address bit A26 to 1 while sending commands to access the second die of S70GL02GS.
The device S70GL02GS (001-98296 Rev H) is a dual die stack comprising two S29GL01GS (001-98285 Rev K) die connected in parallel, but with only one chip select (CS#) signal. This means each die receives commands in parallel. The low address die accepts commands with A26 = 0, while the high address die accepts commands with A26 = 1. You can manage this by adding the base address for each die to each address argument for each command; the base address for first die is 0x0 and for the second die is 0x4000000.
Command sequence to erase first sector in die 1:
- Address 0x555 / Data 0xAA ; 1st unlock cycle
- Address 0x2AA / Data 0x55 ; 2nd unlock cycle
- Address 0x555 / Data 0x80 ; 1st command cycle
- Address 0x555 / Data 0xAA ; 2nd command cycle
- Address 0x2AA / Data 0x55 ; 3rd command cycle
Address 0x0000000 / Data 0x30 ;Sector Address / Sector Erase Command
Command sequence to erase first sector in die 2:
- Address 0x4000555 / Data 0xAA ; 1st unlock cycle
- Address 0x40002AA / Data 0x55 ; 2nd unlock cycle
- Address 0x4000555 / Data 0x80 ; 1 st command cycle
- Address 0x4000555 / Data 0xAA ; 2 nd command cycle
- Address 0x40002AA / Data 0x55 ; 3 rd command cycle
- Address 0x4000000 / Data 0x30 ; Sector Address / Sector Erase Command
No special address manipulation is required for reading the main flash array. While reading you cannot tell that there are two flash die – only that there is a continuous address space that spans both flash chips.
The special address manipulation is required for writing commands and receiving command response. Many commands have “unlock cycles” consisting of the 555h/AAh and 2AAh/55h address/data pattern. For these cycles A26 must be set correctly, so the unlock cycles are accepted by the intended flash die. Some commands also have address arguments that must be directed to the correct die via A26. These arguments are:
- RA = Read Address
- PA = Program Address
- SA = Sector Address
- WBL = Write Buffer Location
- PWA = PassWord Address
- XXX = Don’t Care (for single die only)
Here is a partial table of commands from the GL-S datasheet (001-98285 Rev K) where the affected address arguments are highlighted: