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8XC51FX Datasheet(PDF) 17 Page - Intel Corporation

No. de Pieza. 8XC51FX
Descripción  CHMOS SINGLE-CHIP 8-BIT MICROCONTROLLERS
Descarga  20 Pages
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Fabricante  INTEL [Intel Corporation]
Página de inicio  http://www.intel.com
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8XC51FX Datasheet(HTML) 17 Page - Intel Corporation

 
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8XC51FX
PROGRAMMING ALGORITHM
Refer to Table 4 and Figures 10 and 11 for address
data and control signals set up To program the
87C51FX the following sequence must be exercised
1 Input the valid address on the address lines
2 Input the appropriate data byte on the data
lines
3 Activate the correct combination of control sig-
nals
4 Raise EA VPP from VCC to 1275V g025V
5 Pulse ALEPROG 5 times for the EPROM ar-
ray and 25 times for the encryption table and
the lock bits
Repeat 1 through 5 changing the address and data
for the entire array or until the end of the object file is
reached
PROGRAM VERIFY
Program verify may be done after each byte or block
of bytes is programmed In either case a complete
verify of the programmed array will ensure reliable
programming of the 87C51FX
The lock bits cannot be directly verified Verification
of the lock bits is done by observing that their fea-
tures are enabled
272322 – 21
Figure 11 Programming Signals Waveforms
ROM and EPROM Lock System
The 87C51FX program lock system
when pro-
grammed protects the onboard program against
software piracy
The 83C51FX 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 83C51FA
does not have protection features
The 87C51FX 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
Table 5 Program Lock Bits and the Features
Program Lock Bits
ProtectIon Type
LB1
LB2
LB3
1
U
U
U
No Program Lock features enabled (Code verify will still be encrypted by the
Encryption Array if programmed)
2
P
U
U
MOVC instructions executed from external program memory are disabled from
fetching code bytes from internal memory EA is sampled and latched on Reset and
further programming of the EPROM is disabled
3
P
P
U
Same as 2 also verify is disabled
4
P
P
P
Same as 3 also external execution is disabled
Any other combination of the lock bits is not defined
17


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