W77IE58 Datasheet, PDF (79/90 Pages) Winbond – 8-BIT MICROCONTROLLER

Preliminary W77IE58
B0: Lock bit
This bit is used to protect the customer's program code in the W77IE58. It may be set after the
programmer finishes the programming and verifies sequence. Once this bit is set to logic 0, both the
FLASH ROM data and Special Setting Registers can not be accessed again.
B1: MOVC Inhibit
This bit is used to restrict the accessible region of the MOVC instruction. It can prevent the MOVC
instruction in external program memory from reading the internal program code. When this bit is set to
logic 0, a MOVC instruction in external program memory space will be able to access code only in the
external memory, not in the internal memory. A MOVC instruction in internal program memory space will
always be able to access the ROM data in both internal and external memory. If this bit is logic 1, there
are no restrictions on the MOVC instruction.
B2: Encryption Feature
Both the Seed 0 and Seed 1 are a one-byte flash memory cell that provide the user with encryption code
protection. When program code is programmed to the W77IE58 internal FLASH ROM and verify it is
correct, then users can program a non-FFh value into either Seed 0 or Seed 1 to start the encryption
logic. When Seed 0 or Seed 1 is presented in non-FFh state, the internal encryption circuit will generate
a sequence of random values, then add to each the program code bytes before they appear in the data
bus. Now the code is scrambled during the read or verify operation. The Seed 0 and Seed 1 have the
initial value FFh after chip erased. When the encryption logic is effective, the user can not disable it
except by erasing the chip to recover the Seed 0 and 1 to initial value FFh. The method for
programming Seed 0 and Seed 1 is the same as that used to program internal FLASH ROM, except
that the address of Seed 0 is 0FF7Fh, and Seed 1 is 0FF3Fh. When B2 bit is cleared, Seed 0 and
Seed 1 can not be accessed.
ABSOLUTE MAXIMUM RATINGS
PARAMETER
DC Power Supply
Input Voltage
Operating Temperature
Storage Temperatute
SYMBOL
VDD−VSS
VIN
TA
Tst
CONDITION
-0.3
VSS-0.3
-40
-55
RATING
+7.0
VDD+0.3
+85
+150
UNIT
V
V
°C
°C
Note: Exposure to conditions beyond those listed under Absolute Maximum Ratings may adversely affect the life and reliability
of the device.
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Publication Release Date: July 2000
Revision A1