M295V400B-120M1R Ver la hoja de datos (PDF) - STMicroelectronics

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M295V400B-120M1R

4 Mbit (512Kb x8 or 256Kb x16, Boot Block)Single Supply Flash Memory

STMicroelectronics 

M29F400T, M29F400B

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 address and data sequences. The in-

structions require from 1 to 6 cycles, the first or first

three of which are always write operations used to

initiate the instruction. They are followed by either

further write cycles to confirm the first command or

execute 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.

Any read attempt during Program or Erase com-

mand execution will automatically output 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 100µs, 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 block being erasedand thedata value on 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.

Toggle Bit (DQ6). When Programming or Erasing

operations are in progress, successive attempts to

read DQ6 will output complementary data. DQ6 will

toggle following toggling of either G, or E when G

is low. The operation is completed when two suc-

cessive reads yield the same output data. The next

read will outputthe bit last programmed or a ’1’ after

erasing. The toggle bit DQ6 is valid only during

P/E.C. operations, that is after the fourth W pulse

for programming or after the sixth W pulse for

Erase. If the blocks selected for erasure are pro-

tected, DQ6 will toggle for about 100µs and then

return back to Read. DQ6 will be set to ’1’ if a Read

operation is attempted on an EraseSuspend block.

When erase is suspended DQ6 will toggle during

programming operations in a block different to the

block in Erase Suspend. Either E or G toggling will

cause DQ6 to toggle. See Figure 12 for Toggle Bit

flowchart and Figure 13 for Toggle Bit waveforms.

Table 7. Commands

Hex Code

Command

00h

Invalid/Reserved

10h

Chip Erase Confirm

20h

Reserved

30h

Block Erase Resume/Confirm

80h

Set-up Erase

90h

Read Electronic Signature/

Block Protection Status

A0h

Program

B0h

Erase Suspend

F0h

Read Array/Reset

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