m29f400b-120n6tr STMicroelectronics, m29f400b-120n6tr Datasheet - Page 17

• Manufacturer Part Number: m29f400b-120n6tr
• Description: 4 Mbit 512kb X8 Or 256kb X16, Boot Block Single Supply Flash Memory
• Manufacturer: STMicroelectronics

M29F400BT, M29F400BB
4.3
4.4
4.5
4.6
Program command
The Program command can be used to program a value to one address in the memory array
at a time. The command requires four Bus Write operations, the final write operation latches
the address and data in the internal state machine and starts the Program/Erase Controller.
If the address falls in a protected block then the Program command is ignored, the data
remains unchanged. The Status Register is never read and no error condition is given.
During the program operation the memory will ignore all commands. It is not possible to
issue any command to abort or pause the operation. Typical program times are given in
Table
on the Data Inputs/Outputs. See the section on the Status Register for more details.
After the program operation has completed the memory will return to the Read mode, unless
an error has occurred. When an error occurs the memory will continue to output the Status
Register. A Read/Reset command must be issued to reset the error condition and return to
Read mode.
Note that the Program command cannot change a bit set at ’0’ back to ’1’. One of the Erase
Commands must be used to set all the bits in a block or in the whole memory from ’0’ to ’1’.
Unlock Bypass command
The Unlock Bypass command is used in conjunction with the Unlock Bypass Program
command to program the memory. When the access time to the device is long (as with
some EPROM programmers) considerable time saving can be made by using these
commands. Three Bus Write operations are required to issue the Unlock Bypass command.
Once the Unlock Bypass command has been issued the memory will only accept the Unlock
Bypass Program command and the Unlock Bypass Reset command. The memory can be
read as if in Read mode.
Unlock Bypass Program command
The Unlock Bypass Program command can be used to program one address in memory at
a time. The command requires two Bus Write operations, the final write operation latches
the address and data in the internal state machine and starts the Program/Erase Controller.
The Program operation using the Unlock Bypass Program command behaves identically to
the Program operation using the Program command. A protected block cannot be
programmed; the operation cannot be aborted and the Status Register is read. Errors must
be reset using the Read/Reset command, which leaves the device in Unlock Bypass Mode.
See the Program command for details on the behavior.
Unlock Bypass Reset command
The Unlock Bypass Reset command can be used to return to Read/Reset mode from
Unlock Bypass Mode. Two Bus Write operations are required to issue the Unlock Bypass
Reset command.
8.. Bus Read operations during the program operation will output the Status Register
Command interface
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