PSD4235G2-12UT datasheet(43/124 Pages) STMICROELECTRONICS

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PSD4235G2V

Erasing Flash memory

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Erasing Flash memory

9.1

Flash Bulk Erase

The Flash Bulk Erase instruction uses six WRITE operations followed by a READ operation

of the status register, as described in Table 28. If any byte of the Bulk Erase instruction is

wrong, the Bulk Erase instruction aborts and the device is reset to the Read Memory mode.

During a Bulk Erase, the memory status may be checked by reading the Error Flag bit

(DQ5/DQ13), the Toggle Flag bit (DQ6/DQ14), and the Data Polling bit (DQ7/DQ15), as

detailed in Section 8: Programming Flash memory. The Error Flag bit (DQ5/DQ13) returns a

’1’ if there has been an Erase Failure (maximum number of Erase cycles have been

executed).

It is not necessary to program the memory with 00h because the PSD automatically does

this before erasing to 0FFh.

During execution of the Bulk Erase instruction, the Flash memory does not accept any

instructions.

Flash Sector Erase

The Sector Erase instruction uses six WRITE operations, as described in Table 28.

Additional Flash Sector Erase confirm commands and Flash memory sector addresses can

be written subsequently to erase other Flash memory sectors in parallel, without further

coded cycles, if the additional commands are transmitted in a shorter time than the timeout

period of about 100 µs. The input of a new Sector Erase command restarts the timeout

period.

The status of the internal timer can be monitored through the level of the Erase timeout Flag

bit (DQ3/DQ11). If the Erase timeout Flag bit (DQ3/DQ11) is 0, the Sector Erase instruction

has been received and the timeout period is counting. If the Erase timeout Flag bit

(DQ3/DQ11) is 1, the timeout period has expired and the PSD is busy erasing the Flash

memory sector(s). Before and during Erase timeout, any instruction other than Suspend

Sector Erase and Resume Sector Erase, abort the cycle that is currently in progress, and

reset the device to READ mode. It is not necessary to program the Flash memory sector

with 00h as the PSD does this automatically before erasing.

During a Sector Erase, the memory status may be checked by reading the Error Flag bit

(DQ5/DQ13), the Toggle Flag bit (DQ6/DQ14), and the Data Polling bit (DQ7/DQ15), as

detailed in Section 8: Programming Flash memory.

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 resumed.

PSD4235G2-12UT Datasheet(PDF) 43 Page - STMicroelectronics