W78LE51C Datasheet, PDF (10/23 Pages) Winbond – 8-BIT MICROCONTROLLER

W78LE51C/W78L051C
6. ON-CHIP FLASH EPROM CHARACTERISTICS
7. SECURITY BITS
During the on-chip Flash EPROM operation mode, the Flash EPROM can be programmed and
verified repeatedly. Until the code inside the Flash EPROM is confirmed OK, the code can be
protected. The protection of Flash EPROM and those operations on it are described below. The
W78L051C has a Special Setting Register, the Security Register, which can not be accessed in
normal mode. The Security register can only be accessed from the Flash EPROM operation mode.
Those bits of the Security Registers can not be changed once they have been programmed from high
to low. They can only be reset through erase-all operation. The Security Register is addressed in the
Flash EPROM operation mode by address #0FFFFh.
D7 D6 D5 D4 D3 D2 D1 D0
B7 Reserved B2 B1 B0
Security Bits
B0 : Lock bit, logic 0 : active
B1 : MOVC inhibit,
logic 0 : the MOVC instruction in external memory
cannot access the code in internal memory.
logic 1 : no restriction.
B2 : Encryption
logic 0 : the encryption logic enable
logic 1 : the encryption logic disable
B7 : Osillator Control
logic 0 : 1/2 gain
logic 1 : Full gain
Default 1 for all security bits.
Reserved bits must be kept in logic 1.
4KB Flash EPROM ^0000h
Program Memory
Reserved
0FFFh
Security Register _0FFFFh
Special Setting Register
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