HT85F2250 datasheet(37/187 Pages) HOLTEK

37 / 187 page

Rev. 1.10

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A/D Flash 8051 Core Low Pin Count MCU

HT85F2250/HT85F2262

FMKEY Register – Flash Program Memory Unlock Key Data Register

SFR Address: F9h

Bit

Name

FMKEY7

FMKEY6

FMKEY�

FMKEY4

FMKEY�

FMKEY � FMKEY 1 FMKEY 0

R/W

POR

Bit 7~0

Flash Memory Unlock Key Data register Unlock Data bits 7~bit 0

The FMKEY register is the Flash Memory Unlock key data register. If a correct key

data sequence has been written into this register, the Flash memory will release its

locked status; otherwise, the Flash memory will remain in its locked status. The correct

sequence to be written is 55H, AAH, 00H and then FFH. It is recommended to write

the key data sequence to the FMKEY register in four consecutive instructions. When

the program memory is in an unlocked status, writing any data to the FMKEY register

will result in the program memory being locked again. If there is no need to update the

program memory, it’s strongly recommended to lock the program memory at all times.

FMSR Register – Flash Program Memory Status Register

SFR Address: E2h

Bit

Name

UNLOCK

—

FMPF

FMSEF

FMBF

FMBUSY

R/W

—

POR

—

Bit 7

UNLOCK: Flash Memory Controller Unlock flag

0: Indicated Flash Memory Controller is locked

1: Indicated Flash Memory Controller is unlocked

Bit 6~4

Unimplemented, read as “0”

Bit 3

FMPF: Flash Memory Controller Procedure flag

0: The Flash Memory Controller Procedure Flag is cleared to 0 if FMSEF=1, or if

FMBF=1 or if the IAP Procedure has ended.

1: Flash Memory Controller Procedure is corrected

Bit 2

FMSEF: Flash Memory Controller Security Error Flag

0: Manipulation of Flash Memory does not violate the security rule

1: Manipulation of Flash Memory violates the security rule

After a flash memory manipulation, this bit must be checked to determine if the Flash

Memory manipulation has violated the security rule or not. The security rule means

to write a FFH value to SECURITY1[N] or SECURITY2[N] to set the sector N in the

unprotected mode before a flash memory manipulation. Otherwise, the manipulation

violates the security rule and the FMSEF flag will be set.

Bit 1

FMBF: Flash Memory Controller Break Flag

0: Manipulation of Flash Memory does not violate the security rules or lock rules or

FMCR mode change

1: Manipulation of Flash Memory violates the security rules or lock rules or FMCR

mode change

Bit 0

FMBUSY: Flash Memory Controller Status indication bit

0: Not erasing or rewriting

1: Busy

HT85F2250 数据表(PDF) 37 Page - Holtek Semiconductor Inc

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