HT85F2270 datasheet(42/226 Pages) HOLTEK

42 / 226 page

Rev. 1.00

4� of ��6

�a� 1�� 01�

Standard 8051 8-Bit Flash MCU

HT85F2260/HT85F2270/HT85F2280

Program Memory Protection

The flash program memory is partitioned into 2 memory blocks. One is the main memory block

and the other is the ID block. The ID block size is 256 bytes and is used to setup the protected

sectors. This memory protection function is used to protect the Program Memory from improper

Program, Erase or Read operations. The flash program memory is divided into several sectors

related to the memory size. Each sector has a capacity of 4K bytes. The memory protection

function is implemented by register control. If a value, with the exception of 0FFH, is written into

the corresponding control register, the corresponding sector program memory protection function

will be enabled. This program memory sector will then be unable to be programmed, erased or read

by corresponding instructions. In this way, the user can select which block of the flash memory is

to be protected.

Memory Protection Control Bytes

The protection of program code memory is categorised to two types: Security Type 1 and Security

Type 2.

■

Security Type 1

For the HT85F2280 device, the inhibit bytes SECURITY1[0:15] are located at the address

0x00~0x0F of the ID block page 0. If a value, with the exception of 0FFH, is written into these

bytes, the sectors corresponding to SECURITY1[0:15] cannot be programmed, erased or read by

the ICP. For the IAP program, when in the OCDS mode, any sector N with a security mechanism

can be protected from being programmed, erased or read by the OCDSINSTR instruction. But

when in the main program, all sector N with security or not, can be programmed, erased or read

by the IAP. For the MOVC instructions, any sector N with security mechanism cannot be read by

the ocdsinstr instruction when in the OCDS mode, but still can be read by MOVC instructions

when in the main program. Since these bytes can only be written once, to release the respective

sectors in the unprotected mode, the device must be erased.

The following table illustrates the protection status when in the OCDS/ICP/IAP/MOVC modes

when the SECURITY1[0:15] bytes are written with a value other than 0FFH:

SECURITY1[N]

N=0~15

Program

Erase

Read

Protect

Sector #

Remove

Protection

ICP

N/A(1)

Erase All

IAP

OCDS(�)

X(�)

X(4)

Erase All

�ain Program

O(�)

Erase All

�

OCDS(�)

N/A(�)

X(4)

Erase All

�ain Program

N/A(�)

Erase All

Note: (1) “N/A” means no path to read RO� code.

(�) “N/A” means none of these functions.

(�) “X” stands for inhibited; “O” stands for enabled.

(4) If a read operation is inhibited, reading the Flash will return a fixed Flash code of 00H.

(�) When in the OCDS mode� onl� the OCDSINSTR instruction has the securit� protection

mechanism.

HT85F2270 датащи(PDF) 42 Page - Holtek Semiconductor Inc

HT85F2270 датащи(HTML) 42 Page - Holtek Semiconductor Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL