M28W800 datasheet(39/42 Pages) STMICROELECTRONICS

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M28W800BT, M28W800BB

Figure 19. Erase Flowchart and Pseudo Code

Note: If an error is found, the Status Register must be cleared before further Program/Erase operations.

Write 20h

AI03541b

Start

Write Block

Address & D0h

Read Status

YES

b7 = 1

YES

b3 = 0

YES

b4, b5 = 1

VPP Invalid

Error (1)

Command

Sequence Error (1)

b5 = 0

Erase Error (1)

End

YES

b1 = 0

Erase to Protected

Block Error (1)

YES

erase_command ( blockToErase ) {

writeToFlash (any_address, 0x20) ;

writeToFlash (blockToErase, 0xD0) ;

/* only A12-A20 are significannt */

/* Memory enters read status state after

the Erase Command */

} while (status_register.b7== 0) ;

do {

status_register=readFlash (any_address) ;

/* E or G must be toggled*/

if (status_register.b3==1) /*VPP invalid error */

error_handler ( ) ;

if ( (status_register.b4==1) && (status_register.b5==1) )

/* command sequence error */

error_handler ( ) ;

if (status_register.b1==1) /*program to protect block error */

error_handler ( ) ;

if ( (status_register.b5==1) )

/* erase error */

error_handler ( ) ;

}

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