Numonyx™ Wireless Flash Memory (W18)
Figure 31: Block Locking State Diagram
Power-Up/Reset
Locked
[X01]
Locked-
Down
4,5
[011]
Hardware
Locked
5
[011]
WP# Hardware Control
Unlocked
[X00]
Software
Locked
[111]
Unlocked
[110]
Software Block Lock (0x60/0x01) or Software Block Unlock (0x60/0xD0)
Software Block Lock-Down (0x60/0x2F)
WP# hardware control
Notes:
1. [a,b,c] represents [WP#, D1, D0]. X = Don’t Care.
2. D1 indicates block Lock-down status. D1 = ‘0’, Lock-down has not been issued to
this block. D1 = ‘1’, Lock-down has been issued to this block.
3. D0 indicates block lock status. D0 = ‘0’, block is unlocked. D0 = ‘1’, block is locked.
4. Locked-down = Hardware + Software locked.
5. [011] states should be tracked by system software to determine difference between
Hardware Locked and Locked-Down states.
13.1.1
Lock
All blocks default to locked (state [x01]) after initial power-up or reset. Locked blocks
are fully protected from alteration. Attempted program or erase operations to a locked
block will return an error in SR[1]. Unlocked blocks can be locked by using the Lock
Block command sequence. Similarly, a locked block’s status can be changed to
unlocked or lock-down using the appropriate software commands.
13.1.2
Unlock
Unlocked blocks (states [x00] and [110]) can be programmed or erased. All unlocked
blocks return to the locked state when the device is reset or powered-down. An
unlocked block’s status can be changed to the locked or locked-down state using the
appropriate software commands. A locked block can be unlocked by writing the Unlock
Block command sequence if the block is not locked-down.
13.1.3
Lock-Down
Locked-down blocks (state [011]) offer the user an additional level of write protection
beyond that of a regular locked block. A block that is locked-down cannot have it’s
state changed by software if WP# is asserted. A locked or unlocked block can be
locked-down by writing the Lock-Down Block command sequence. If a block was set to
locked-down, then later changed to unlocked, a Lock-Down command should be issued
prior asserting WP# will put that block back to the locked-down state. When WP# is
deasserted, locked-down blocks are changed to the locked state and can then be
unlocked by the Unlock Block command.
Datasheet
72
November 2007
Order Number: 290701-18
NUMONYX [ NUMONYX B.V ]
