28F002BC Datasheet, PDF (18/37 Pages) Intel Corporation – 28F002BC 2-MBIT (256K X 8) BOOT BLOCK FLASH MEMORY

28F002BC 2-MBIT BOOT BLOCK FLASH MEMORY
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Table 5. Status Register Bit Definition
WSMS
ESS
ES
DWS
VPPS
R
R
R
7
6
5
4
3
2
1
0
NOTES:
SR.7 = WRITE STATE MACHINE STATUS (WSMS)
1 = Ready
0 = Busy
The Write State Machine bit must first be checked to
determine program or Block Erase completion,
before the Program or Erase Status bits are checked
for success.
SR.6 = ERASE-SUSPEND STATUS (ESS)
1 = Erase Suspended
0 = Erase In Progress/Completed
When Erase Suspend is issued, the WSM halts
execution and sets both the WSMS and ESS bits to
“1.” The ESS bit remains set to “1” until an Erase
Resume command is issued.
SR.5 = ERASE STATUS
1 = Error In Block Erasure
0 = Successful Block Erase
When this bit is set to “1,” the WSM has applied the
maximum number of erase pulses to the block and is
still unable to successfully verify block erasure.
SR.4 = PROGRAM STATUS
1 = Error in Byte Program
0 = Successful Byte Program
When this bit is set to “1,” the WSM has attempted
but failed to program a byte.
SR.3 = VPP STATUS
1 = VPP Low Detect, Operation Abort
0 = VPP OK
SR.2–SR.0 = RESERVED FOR FUTURE
ENHANCEMENTS
The VPP Status bit, unlike an A/D converter, does not
provide continuous indication of VPP level, but it does
check the VPP level intermittently. The WSM
interrogates VPP level only after the program or
erase command sequences have been entered, and
informs the system if VPP has not been switched on.
If VPP ever goes below VPPLK (even during an Erase
Suspend), the status register will set this bit and
abort the operation in progress, even if VPP is
returned to a valid level. The VPP Status bit is not
guaranteed to report accurate feedback between
VPPLK and VPPH.
These bits are reserved for future use and should be
masked out when polling the status register.
3.3.4
ERASE MODE
Erase Setup and Erase Confirm commands to the
CUI, along with the address identifying the block to
be erased. This address is latched internally when
the Erase Confirm command is issued. Block
erasure results in all bits within the block being set
to “1.”
If the Erase Confirm command does not follow the
Erase Setup command, the status register
responds by setting both SR.4 and SR.5 to “1” to
indicate an invalid command sequence. The WSM
returns to read status register mode.
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The WSM then executes a sequence of internally
timed events to:
1. Program all bits within the block to “0.”
2. Verify that all bits within the block are
sufficiently programmed to “0.”
3. Erase all bits within the block (set all bits to “1”).
4. Verify that all bits within the block are
sufficiently erased.
While the erase sequence is executing, bit 7 of the
status register is a “0.”
PRELIMINARY