Intel StrataFlash® Wireless Memory (L18)
12.0
Erase Operations
Flash erasing is performed on a block basis. An entire block is erased each time an erase command
sequence is issued, and only one block is erased at a time. When a block is erased, all bits within
that block read as logical ones. The following sections describe block erase operations in detail.
12.1
Block Erase
Block erase operations are initiated by writing the Block Erase Setup command to the address of
the block to be erased (see Section 9.2, “Device Commands” on page 47). Next, the Block Erase
Confirm command is written to the address of the block to be erased. Erasing can occur in only one
partition at a time; all other partitions must be in a read state. If the device is placed in standby
(CE# deasserted) during an erase operation, the device completes the erase operation before
entering standby.VPP must be above VPPLK and the block must be unlocked (see Figure 43, “Block
Erase Flowchart” on page 89).
During a block erase, the Write State Machine (WSM) executes a sequence of internally-timed
events that conditions, erases, and verifies all bits within the block. Erasing the flash memory array
changes “zeros” to “ones.” Memory array bits that are ones can be changed to zeros only by
programming the block (see Section 11.0, “Programming Operations” on page 58).
The Status Register can be examined for block erase progress and errors by reading any address
within the partition that is being erased. The partition remains in the Read Status Register state
until another command is written to that partition. Issuing the Read Status Register command to
another partition address sets that partition to the Read Status Register state, allowing erase
progress to be monitored at that partition’s address. SR[0] indicates whether the addressed partition
or another partition is erasing. The partition’s Status Register bit SR[7] is set upon erase
completion.
Status Register bit SR[7] indicates block erase status while the sequence executes. When the erase
operation has finished, Status Register bit SR[5] indicates an erase failure if set. SR[3] set would
indicate that the WSM could not perform the erase operation because VPP was outside of its
acceptable limits. SR[1] set indicates that the erase operation attempted to erase a locked block,
causing the operation to abort.
Before issuing a new command, the Status Register contents should be examined and then cleared
using the Clear Status Register command. Any valid command can follow once the block erase
operation has completed.
12.2
Erase Suspend
Issuing the Erase Suspend command while erasing suspends the block erase operation. This allows
data to be accessed from memory locations other than the one being erased. The Erase Suspend
command can be issued to any device address; the corresponding partition is not affected. A block
erase operation can be suspended to perform a word or buffer program operation, or a read
operation within any block except the block that is erase suspended (see Figure 40, “Program
Suspend/Resume Flowchart” on page 86).
April 2005
64
Intel StrataFlash® Wireless Memory (L18)
Order Number: 251902, Revision: 009
Datasheet
INTEL [ INTEL ]
