W78E51B-40 WINBOND [Winbond], W78E51B-40 Datasheet - Page 11

• Manufacturer Part Number: W78E51B-40
• Description: 8-BIT MTP MICROCONTROLLER
• Manufacturer: WINBOND [Winbond]

Lock bit
This bit is used to protect the customer's program code in the W78E51B. It may be set after the
programmer finishes the programming and verifies sequence. Once this bit is set to logic 0, both the
MTP ROM data and Special Setting Registers can not be accessed again.
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.
Encryption
This bit is used to enable/disable the encryption logic for code protection. Once encryption feature is
enabled, the data presented on port 0 will be encoded via encryption logic. Only whole chip erase will
reset this bit.
A0 to A7
Default 1 for all security bits.
B2 : Encryption
D7 D6 D5 D4 D3 D2 D1 D0
B0 : Lock bit, logic 0 : active
B1 : MOVC inhibit,
B7 : Osillator Control
B7
V
V
1 1 0 1 1 0 1 0
1 1 1
V
V
V
V
IL
IL
IL
IL
IL
IH
Programming Configuration
logic 1 : Full gain
logic 0 : 1/2 gain
logic 0 : the encryption logic enable
logic 1 : the encryption logic disable
logic 0 : the MOVC instruction in external memory
logic 1 : no restriction.
Reserved
P1
P3.0
P3.1
P3.2
P3.3
P3.6
P3.7
X'tal1
X'tal2
Vss
0
cannot access the code in internal memory.
0 0
EA/Vpp
PSEN
B2
ALE
RST
V
P2
P0
DD
B1
0 0
+5V
B0
Reserved bits must be kept in logic 1.
PGM DATA
V
V
V
V
A8 to A15
CP
IL
IH
IH
Special Setting Registers
Company ID (#DAH)
Device ID (#E0H)
Security Bits
- 11 -
A0 to A7
V
V
V
V
V
V
IL
IL
IL
IL
IH
IL
Programming Verification
Preliminary W78E51B
Publication Release Date: December 1998
4KB MTP ROM
Program Memory
P1
P3.0
P3.1
P3.2
P3.3
P3.6
P3.7
X'tal1
X'tal2
Vss
Security Register
Reserved
EA/Vpp
PSEN
RST
ALE
V
P0
P2
DD
+5V
0FFFFh
0000h
0FFFh
PGM DATA
V
V
V
V
A8 to A15
CP
IL
IH
IH
Revision A1