ST92F120 datasheet(45/324 Pages) STMICROELECTRONICS

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ST92F120 - SINGLE VOLTAGE FLASH & EEPROM

3.3.2 Status Registers

During a Flash or an EEPROM write operation any

attempt to read the memory under modification will

output invalid data (FFh equivalent to a NOP in-

struction). This means that the Flash memory is

not fetchable when a write operation is active: the

write operation commands must be given from an-

other memory (EEPROM, internal RAM, or exter-

nal memory).

Two Status Registers (FESR[1:0] are available to

check the status of the current write operation in

Flash and EEPROM memories.

FLASH & EEPROM STATUS REGISTER 0

(FESR0)

Address: 224002h -Read/Write

Reset value: 0000 0000 (00h)

Bit 7 = FEERR:

Flash or EEPROM write ERRor

(Read/Write).

This bit is set by hardware when an error occurs

during a Flash or an EEPROM write operation. It

must be cleared by software.

0: Write OK

1: Flash or EEPROM write error

Bits 6:0 = FESS[6:0].

Flash and EEPROM Status

Sector 6-0 (Read Only).

These bits are set by hardware and give the status

of the 7 Flash and EEPROM sectors (TF, E1, E0,

F3, F2, F1, F0). The meaning of FESSx bit for sec-

tor x is given by the following table:

FLASH & EEPROM STATUS REGISTER 1

(FESR1)

Address: 224003h -Read Only

Reset value: 0000 0000 (00h)

Bit 7 = ERER.

Erase error (Read Only).

This bit is set by hardware when an Erase error oc-

curs during a Flash or an EEPROM write opera-

tion. This error is due to a real failure of a Flash

cell, that can not be erased anymore. This kind of

error is fatal and the sector where it occurred must

be discarded (if it was in one of the EEPROM sec-

tors, the hardware emulation can not be used any-

more). This bit is automatically cleared when bit

FEERR of the FESR0 register is cleared by soft-

ware.

0: Erase OK

1: Erase error

Bit 6 = PGER.

Program error (Read Only).

This bit is automatically set when a Program error

occurs during a Flash or an EEPROM write opera-

tion. This error is due to a real failure of a Flash

cell, that can not be programmed anymore. The

byte where this error occurred must be discarded

(if it was in the EEPROM memory, the byte must

be reprogrammed to FFh and then discarded, to

avoid the error occurring again when that byte is

internally moved). This bit is automatically cleared

when bit FEERR of the FESR0 register is cleared

by software.

0: Program OK

1: Flash or EEPROM Programming error

321

FEER

FESS

Table 9. FESSx bit Values

FEERR

FBUSY

EBUSY

FSUSP

FESSx=1

meaning

Write Error in

Sector x

Write operation

on-going in sec-

tor x

001

Sector Erase

Suspended in

sector x

000

Don’t care

654

ERER PGER

SWE

Table 9. FESSx bit Values

FEERR

FBUSY

EBUSY

FSUSP

FESSx=1

meaning

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