參數(shù)資料
型號(hào)： 8XC51R
廠商： Intel Corp.
英文描述： CHMOS SINGLE-CHIP 8-BIT MICROCONTROLLER
中文描述： CHMOS單片8位微控制器
文件頁(yè)數(shù)： 18/20頁(yè)
文件大?。?/td> 294K
代理商： 8XC51R
8XC51RA/RB/RC
ROM and EPROM Lock System
The program lock system, when programmed, pro-
tects the onboard program against software piracy.
The 83C51RX has a one-level program lock system
and a 64-byte encryption table. See line 2 of Table
5. If program protection is desired. the user submits
the encryption table with their code. and both the
lock-bit and encryption array are programmed by the
factory. The encryption array is not available without
the lock bit. For the lock bit to be programmed, the
user must submit an encryption table.
The 87C51RX has a 3-level program lock system
and a 64-byte encryption array. Since this is an
EPROM device, all locations are user-programma-
ble. See Table 5.
Encryption Array
Within the EPROM array are 64 bytes of Encryption
Array that are initially unprogrammed (all 1’s). Every
time that a byte is addressed during a verify, 6 ad-
dress lines are used to select a byte of the Encryp-
tion Array. This byte is then exclusive-NOR’ed
(XNOR) with the code byte, creating an Encryption
Verify byte. The algorithm, with the array in the un-
programmed state (all 1’s), will return the code in its
original, unmodified form. For programming the En-
cryption Array, refer to Table 4 (Programming the
EPROM).
When using the encryption array, one important fac-
tor needs to be considered. If a code byte has the
value 0FFH, verifying the byte will produce the en-
cryption byte value. If a large block (
l
64 bytes) of
code is left unprogrammed, a verification routine will
display the contents of the encryption array. For this
reason all unused code bytes should be pro-
grammed with some value other than 0FFH, and not
all of them the same value. This will ensure maxi-
mum program protection.
Program Lock Bits
The 87C51RX has 3 programmable lock bits that
when programmed according to Table 5 will provide
different levels of protection for the on-chip code
and data.
If any program lock bits were programmed, erasing
the EPROM will not erase the program lock bits and
programming of the EPROM is disabled.
Reading the Signature Bytes
The 8XC51RX has 3 signature bytes in locations
30H, 31H, and 60H. To read these bytes follow the
procedure for EPROM verify, but activate the control
lines provided in Table 4 for Read Signature Byte.
Location
Device
Contents
30H
All
89H
31H
All
58H
60H
87C51RC
C2H
87C51RB
C1H
87C51RA
C0H
83C51RC
42H/C2H
83C51RB
41H/C1H
83C51RA
40H/C0H
Erasure Characteristics
(Windowed Packages Only)
Erasure of the EPROM begins to occur when the
chip is exposed to light with wavelength shorter than
approximately 4,000 Angstroms. Since sunlight and
fluorescent lighting have wavelengths in this range,
exposure to these light sources over an extended
time (about 1 week in sunlight, or 3 years in room-
level fluorescent lighting) could cause inadvertent
erasure. If an application subjects the device to this
type of exposure, it is suggested that an opaque la-
bel be placed over the window.
The recommended erasure procedure is exposure
to ultraviolet light (at 2537 Angstroms) to an integrat-
ed dose of at least 15 W-sec/cm
2
. Exposing the
EPROM to an ultraviolet lamp of 12,000
m
W/cm
2
rating for 30 minutes, at a distance of about 1 inch,
should be sufficient.
Erasure leaves all the EPROM Cells in a 1’s state.
18
相關(guān)PDF資料
PDF描述
8XC51RA CHMOS Single-Chip 8-Bit Microcontroller(CHMOS 型單片8位微控制器)
8XC51RB CHMOS Single-Chip 8-Bit Microcontroller(CHMOS 型單片8位微控制器)
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
8XC51RA 制造商:INTEL 制造商全稱:Intel Corporation 功能描述:CHMOS SINGLE-CHIP 8-BIT MICROCONTROLLER
8XC51RA/RB/RC/RD/80C51RA 制造商:未知廠家 制造商全稱:未知廠家 功能描述:(360.35 k)
8XC51RA+ 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:80C51 8-bit microcontroller family 8K-4K/256-1K OTP/ROM/ROMless, low voltage (2.7V-5.5V), low power, high speed (33 MHz)
8XC51RB 制造商:INTEL 制造商全稱:Intel Corporation 功能描述:CHMOS SINGLE-CHIP 8-BIT MICROCONTROLLER
8XC51RB+ 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:80C51 8-bit microcontroller family 8K-4K/256-1K OTP/ROM/ROMless, low voltage (2.7V-5.5V), low power, high speed (33 MHz)
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