PSD813F1 datasheet(23/110 Pages) STMICROELECTRONICS

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PSD813F1

Data Polling Flag (DQ7)

When Erasing or Programming the Flash memory

(or when Writing into the EEPROM memory), bit

DQ7 outputs the complement of the bit being en-

tered for Programming/Writing on DQ7. Once the

Program instruction or the WRITE operation is

completed, the true logic value is read on DQ7 (in

a Read operation). Flash memory specific fea-

tures:

–

Data Polling is effective after the fourth WRITE

pulse (for programming) or after the sixth

WRITE pulse (for Erase). It must be performed

at the address being programmed or at an

address within the Flash sector being erased.

–

During an Erase instruction, DQ7 outputs a ‘0.’

After completion of the instruction, DQ7 will

output the last bit programmed (it is a ‘1’ after

erasing).

–

If the byte to be programmed is in a protected

Flash sector, the instruction is ignored.

–

If all the Flash sectors to be erased are

protected, DQ7 will be set to ‘0’ for about

100µs, and then return to the previous

addressed byte. No erasure will be performed.

Toggle Flag (DQ6)

The PSD offers another way for determining when

the EEPROM write or the Flash memory Program

instruction is completed. During the internal

WRITE operation and when either the FSi or EESi

is true, the DQ6 will toggle from ‘0’ to ‘1’ and ‘1’ to

‘0’ on subsequent attempts to read any byte of the

memory.

When the internal cycle is complete, the toggling

will stop and the data read on the Data Bus D0-7

is the addressed memory byte. The device is now

accessible for a new READ or WRITE operation.

The operation is finished when two successive

reads yield the same output data. Flash memory

specific features:

The Toggle bit is effective after the fourth

WRITE pulse (for programming) or after the

sixth WRITE pulse (for Erase).

If the byte to be programmed belongs to a

protected Flash sector, the instruction is

ignored.

If all the Flash sectors selected for erasure are

protected, DQ6 will toggle to ‘0’ for about 100

µs and then return to the previous addressed

byte.

Error Flag (DQ5)

During a correct Program or Erase, the Error bit

will set to ‘0.’ This bit is set to ‘1’ when there is a

failure during Flash byte programming, Sector

erase, or Bulk Erase.

In the case of Flash programming, the Error Bit in-

dicates the attempt to program a Flash bit(s) from

the programmed state ('0') to the erased state ('1'),

which is not a valid operation. The Error bit may

also indicate a timeout condition while attempting

to program a byte.

In case of an error in Flash sector erase or byte

program, the Flash sector in which the error oc-

curred or to which the programmed byte belongs

must no longer be used. Other Flash sectors may

still be used. The Error bit resets after the Reset in-

struction.

Erase Time-out Flag DQ3 (Flash Memory only)

The Erase Timer bit reflects the time-out period al-

lowed between two consecutive Sector Erase in-

structions. The Erase timer bit is set to ‘0’ after a

Sector Erase instruction for a time period of 100µs

+ 20% unless an additional Sector Erase instruc-

tion is decoded. After this time period or when the

additional Sector Erase instruction is decoded,

DQ3 is set to ‘1.’

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