m29f200t STMicroelectronics, m29f200t Datasheet - Page 8

• Manufacturer Part Number: m29f200t
• Description: 2 Mbit 256kb X8 Or 128kb X16, Boot Block Single Supply Flash Memory
• Manufacturer: STMicroelectronics

M29F200T, M29F200B
Block Temporary Unprotection. Any previously
protected block can be temporarily unprotected in
order to change stored data. The temporaryunpro-
tection mode is activated by bringing RP to V
During the temporary unprotection mode the pre-
viously protected blocks are unprotected. A block
can be selected and data can be modified by
executingthe Erase or Program instruction with the
RP signal held at V
all the previously protected blocks are again pro-
tected.
Block Unprotection. All protected blocks can be
unprotected on programming equipment to allow
updating of bit contents. All blocks must first be
protected before the unprotection operation. Block
unprotection is activated when A9, G and E are at
V
algorithm is shown in Figure 15. Unprotection is
initiated by the edge of W falling to V
of 10ms, the unprotection operation will end. Un-
protectionverify is achieved by bringing G and E to
V
remains at V
output data will yield 00h if the block defined by the
inputs A12-A16 has been succesfully unprotected.
Each block must be separatelyverified by giving its
address in order to ensure that it has been unpro-
tected.
INSTRUCTIONS AND COMMANDS
The Command Interface latches commands writ-
ten to the memory. Instructions are made up from
one or more commands to perform Read Memory
Array, Read Electronic Signature, Read Block Pro-
tection, Program, Block Erase, Chip Erase, Erase
Suspend and Erase Resume. Commands are
made of addressand data sequences. The instruc-
tionsrequire from 1 to 6 cycles,the first or first three
of which are always write operationsused to initiate
the instruction. They are followed by either further
write cycles to confirm the first command or exe-
cute the command immediately. Command se-
quencing must be followed exactly. Any invalid
combination of commands will reset the device to
Read Array. The increased number of cycles has
been chosen to assure maximum data security.
Instructions are initialised by two initial Coded cy-
cles which unlock the Command Interface.In addi-
tion, for Erase, instruction confirmation is again
preceded by the two Coded cycles.
Status Register Bits
P/E.C. status is indicated during execution by Data
Polling on DQ7, detection of Toggle on DQ6 and
DQ2, or Error on DQ5 and Erase Timer DQ3 bits.
8/33
ID
IL
while A0 is at V
and A12, A15 at V
ID
. In these conditions, reading the
ID
IL
, A6 and A1 are at V
. When RP is returned to V
IH
. The Block Unprotection
IL
. Aftera delay
IH
and A9
ID
IH
.
,
Any read attempt during Program or Erase com-
mand executionwill automaticallyoutput these five
Status Register bits. The P/E.C. automatically sets
bits DQ2, DQ3, DQ5, DQ6 and DQ7. Other bits
(DQ0, DQ1 and DQ4) are reserved for future use
and should be masked. See Tables 9 and 10.
Data Polling Bit (DQ7). When Programming op-
erations are in progress, this bit outputs the com-
plement of the bit being programmed on DQ7.
During Erase operation, it outputs a ’0’. After com-
pletion of the operation, DQ7 will output the bit last
programmed or a ’1’ after erasing. Data Polling is
valid and only effective during P/E.C. operation,
that is after the fourth W pulse for programming or
after the sixth W pulse for erase. It must be per-
formed at the address being programmed or at an
address within the block being erased. If all the
blocks selected for erasure are protected, DQ7 will
be set to ’0’ for about 100 s, and then return to the
previous addressed memory data value. See Fig-
ure 11 for the Data Polling flowchart and Figure 10
for the Data Polling waveforms. DQ7 will also flag
the Erase Suspend mode by switching from ’0’ to
’1’ at the start of the Erase Suspend. In order to
monitor DQ7 in the Erase Suspend mode an ad-
dress within a block being erased must be pro-
vided. For a Read Operation in Erase Suspend
mode, DQ7 will output ’1’ if the read is attempted
on a blockbeing erasedand the data valueon other
blocks. During Program operation in Erase Sus-
pend Mode, DQ7 will have the same behaviour as
in the normal program execution outside of the
suspend mode.
Table 7. Commands
Hex Code
00h
10h
20h
30h
80h
90h
A0h
B0h
F0h
Invalid/Reserved
Chip Erase Confirm
Reserved
Block Erase Resume/Confirm
Set-up Erase
Read Electronic Signature/
Block Protection Status
Program
Erase Suspend
Read Array/Reset
Command