M29W800AB STMICROELECTRONICS [STMicroelectronics], M29W800AB Datasheet - Page 12

• Manufacturer Part Number: M29W800AB
• Description: 8 Mbit 1Mb x8 or 512Kb x16, Boot Block Low Voltage Single Supply Flash Memory
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

M29W800AT, M29W800AB
Table 11. Polling and Toggle Bits
Note: 1. Toggle if the address is within a block being erased.
Toggle Bit (DQ2). This toggle bit, together with
DQ6, can be used to determine the device status
during the Erase operations. It can also be used to
identify the block being erased. During Erase or
Erase Suspend a read from a block being erased
will cause DQ2 to toggle. A read from a block not
being erased will set DQ2 to ’1’ during erase and
to DQ2 during Erase Suspend. During Chip Erase
a read operation will cause DQ2 to toggle as all
blocks are being erased. DQ2 will be set to ’1’ dur-
ing program operation and when erase is com-
plete. After erase completion and if the error bit
DQ5 is set to ’1’, DQ2 will toggle if the faulty block
is addressed.
Error Bit (DQ5). This bit is set to ’1’ by the P/E.C.
when there is a failure of programming, block
erase, or chip erase that results in invalid data in
the memory block. In case of an error in block
erase or program, the block in which the error oc-
curred or to which the programmed data belongs,
must be discarded. The DQ5 failure condition will
also appear if a user tries to program a ’1’ to a lo-
cation that is previously programmed to ’0’. Other
Blocks may still be used. The error bit resets after
a Read/Reset (RD) instruction. In case of success
of Program or Erase, the error bit will be set to ’0’.
Erase Timer Bit (DQ3). This bit is set to ’0’ by the
P/E.C. when the last block Erase command has
been entered to the Command Interface and it is
awaiting the Erase start. When the erase timeout
period is finished, after 50 s to 90 s, DQ3 returns
to ’1’.
Coded Cycles
The two Coded cycles unlock the Command Inter-
face. They are followed by an input command or a
confirmation command. The Coded cycles consist
of writing the data AAh at address AAAh in the
Byte-wide configuration and at address 555h in
the Word-wide configuration during the first cycle.
12/33
Program
Erase
Erase Suspend Read
(in Erase Suspend
block)
Erase Suspend Read
(outside Erase Suspend
block)
Erase Suspend Program
’1’ if the address is within a block not being erased.
Mode
DQ7
DQ7
DQ7
DQ7
0
1
Toggle
Toggle
Toggle
DQ6
DQ6
1
Note 1
Toggle
DQ2
DQ2
N/A
1
During the second cycle the Coded cycles consist
of writing the data 55h at address 555h in the Byte-
wide configuration and at address 2AAh in the
Word-wide configuration. In the Byte-wide config-
uration the address lines A–1 to A10 are valid, in
Word-wide A0 to A11 are valid, other address lines
are ’don’t care’. The Coded cycles happen on first
and second cycles of the command write or on the
fourth and fifth cycles.
Instructions
See Table 9.
Read/Reset (RD) Instruction. The Read/Reset
instruction consists of one write cycle giving the
command F0h. It can be optionally preceded by
the two Coded cycles. Subsequent read opera-
tions will read the memory array addressed and
output the data read. A wait state of 10 s is nec-
essary after Read/Reset prior to any valid read if
the memory was in an Erase mode when the RD
instruction is given. The Read/Reset command is
not accepted during Erase and erase Suspend.
Auto Select (AS) Instruction. This
uses the two Coded cycles followed by one write
cycle giving the command 90h to address AAAh in
the Byte-wide configuration or address 555h in the
Word-wide configuration for command set-up. A
subsequent read will output the manufacturer
code and the device code or the block protection
status depending on the levels of A0 and A1. The
manufacturer code, 20h, is output when the ad-
dresses lines A0 and A1 are Low, the device code,
EEh for Top Boot, EFh for Bottom Boot is output
when A0 is High with A1 Low.
The AS instruction also allows access to the block
protection status. After giving the AS instruction,
A0 is set to V
fine the address of the block to be verified. A read
in these conditions will output a 01h if the block is
protected and a 00h if the block is not protected.
Program (PG) Instruction. This instruction uses
four write cycles. Both for Byte-wide configuration
and for Word-wide configuration. The Program
command A0h is written to address AAAh in the
Byte-wide configuration or to address 555h in the
Word-wide configuration on the third cycle after
two Coded cycles. A fourth write operation latches
the Address on the falling edge of W or E and the
Data to be written on the rising edge and starts the
P/E.C. Read operations output the Status Register
bits after the programming has started. Memory
programming is made only by writing ’0’ in place of
’1’. Status bits DQ6 and DQ7 determine if pro-
gramming is on-going and DQ5 allows verification
of any possible error. Programming at an address
not in blocks being erased is also possible during
erase suspend. In this case, DQ2 will toggle at the
address being programmed.
IL
with A1 at V
IH
, while A12-A18 de-
instruction