PSD834F2-10J Просмотр технического описания (PDF) - STMicroelectronics

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PSD834F2-10J

Flash PSD, 3.3V Supply, for 8-bit MCUs 2 Mbit + 256 Kbit Dual Flash Memories and 64 Kbit SRAM

STMicroelectronics 

PSD834F2V

Erasing Flash Memory

Flash Bulk Erase. The Flash Bulk Erase instruc-

tion uses six WRITE operations followed by a

READ operation of the status register, as de-

scribed in Table 7. If any byte of the Bulk Erase in-

struction is wrong, the Bulk Erase instruction

aborts and the device is reset to the Read Flash

memory status.

(DQ7) Bit, as detailed in the section entitled “Pro-

gramming Flash Memory”, on page 19.

During execution of the Erase cycle, the Flash

memory accepts only Reset and Suspend Sector

Erase instructions. Erasure of one Flash memory

sector may be suspended, in order to read data

from another Flash memory sector, and then re-

sumed.

During a Bulk Erase, the memory status may be Suspend Sector Erase. When a Sector Erase

checked by reading the Error Flag (DQ5) Bit, the cycle is in progress, the Suspend Sector Erase in-

Toggle Flag (DQ6) Bit, and the Data Polling Flag struction can be used to suspend the cycle by writ-

(DQ7) Bit, as detailed in the section entitled “Pro- ing 0B0h to any address when an appropriate

gramming Flash Memory”, on page 19. The Error Sector Select (FS0-FS7 or CSBOOT0-CSBOOT3)

Flag (DQ5) Bit returns a '1' if there has been an is High. (See Table 7). This allows reading of data

Erase Failure (maximum number of Erase cycles from another Flash memory sector after the Erase

have been executed).

cycle has been suspended. Suspend Sector

It is not necessary to program the memory with Erase is accepted only during an Erase cycle and

00h because the PSD automatically does this be- defaults to READ Mode. A Suspend Sector Erase

fore erasing to 0FFh.

) During execution of the Bulk Erase instruction, the

t(s Flash memory does not accept any instructions.

Flash Sector Erase. The Sector Erase instruc-

c tion uses six WRITE operations, as described in

u Table 7. Additional Flash Sector Erase codes and

rod Flash memory sector addresses can be written

subsequently to erase other Flash memory sec-

P tors in parallel, without further coded cycles, if the

te additional bytes are transmitted in a shorter time

than the time-out period of about 100µs. The input

le of a new Sector Erase code restarts the time-out

o period.

bs The status of the internal timer can be monitored

through the level of the Erase Time-out Flag (DQ3)

O Bit. If the Erase Time-out Flag (DQ3) Bit is '0,' the

- Sector Erase instruction has been received and

) the time-out period is counting. If the Erase Time-

t(s out Flag (DQ3) Bit is '1,' the time-out period has

c expired and the PSD is busy erasing the Flash

u memory sector(s). Before and during Erase time-

d out, any instruction other than Suspend Sector

ro Erase and Resume Sector Erase instructions

abort the cycle that is currently in progress, and re-

P set the device to READ Mode. It is not necessary

te to program the Flash memory sector with 00h as

le the PSD does this automatically before erasing

(byte=FFh).

so During a Sector Erase, the memory status may be

bchecked by reading the Error Flag (DQ5) Bit, the

OToggle Flag (DQ6) Bit, and the Data Polling Flag

instruction executed during an Erase time-out pe-

riod, in addition to suspending the Erase cycle, ter-

minates the time out period.

The Toggle Flag (DQ6) Bit stops toggling when the

PSD internal logic is suspended. The status of this

bit must be monitored at an address within the

Flash memory sector being erased. The Toggle

Flag (DQ6) Bit stops toggling between 0.1µs and

15µs after the Suspend Sector Erase instruction

has been executed. The PSD is then automatically

set to READ Mode.

If an Suspend Sector Erase instruction was exe-

cuted, the following rules apply:

– Attempting to read from a Flash memory sector

that was being erased outputs invalid data.

– Reading from a Flash sector that was not being

erased is valid.

– The Flash memory cannot be programmed, and

only responds to Resume Sector Erase and

Reset Flash instructions (READ is an operation

and is allowed).

– If a Reset Flash instruction is received, data in

the Flash memory sector that was being erased

is invalid.

Resume Sector Erase. If a Suspend Sector

Erase instruction was previously executed, the

erase cycle may be resumed with this instruction.

The Resume Sector Erase instruction consists of

writing 030h to any address while an appropriate

Sector Select (FS0-FS7 or CSBOOT0-CSBOOT3)

is High. (See Table 7.)

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