W925EP01 Datasheet, PDF (81/108 Pages) Winbond – 8-BIT CID MICROCONTROLLER

W925EP01/ W925EP01FG
6.19 Security Bits
Using device programmer, 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 W925EP01 has Special Setting
Register, which can be accessed by device programmer. The register can only be accessed from the
Flash EPROM operation mode. Those bits of the Security Registers cannot be changed once they
have been programmed from high to low. They can only be reset through erase-all operation.
D7 D6 D5 D4 D3 D2 D1 D0
1 1 0 1 1 0 1 0 _{Company ID (#DAH)}
0 1 1 0 0 0 1 0 Device ID (#D4H)
B7 B6 B5 B4 B3 B2 B1 B0 Option0 Bits
B7 B6 B5 B4 B3 B2 B1 B0 ^{Option1 Bits}
Option0 Bits
B1: High/Low speed for EEPROM acess,
logic 0: Low speed
logic 1: High speed
B2: 4MHz/8MHz selection,
logic 0: 8MHz
logic 1: 4MHz
B4: Encryption(Scramble) & Lock bit
logic 0: the encryption logic & lock enable
logic 1: the encryption logic & lock disable
B5: H/W Reboot path
logic 0: enable reboot by P4.7
logic 1: disable reboot by P4.7
Option1 Bits
B2: Sub crystal oscillator starting counter
logic 0: 10 level
logic 1: 16 level
B4: Main crystal oscillator starting counter
logic 0: 16 level
logic 1: 12 level
0000h
4KB Flash EPROM
Program Memory
LDROM
0FFFh
64KB Flash EPROM
Program Memory
RReesseerrvveedd
APROM
Option Registers FFFFh
Special Setting Registers
Default 1 for all security bits.
Reserved bits must be kept in logic 1.
Option0:
B1: High/Low speed for EEPROM access
B2: 4M/8MHz oscillator selection
If this bit is set to logic 0, the oscillator will operate at 8MHz.
If this bit is set to logic 1, the oscillator will operate at 4MHz.
B4: Encryption(Scramble) & Lock bit
This bit is used to protect the customer's program code. It may be set after the programmer finishes
the programming and verifies sequence. Once this bit is set to logic 0, both the Flash EPROM data
and Special Setting Registers cannot be accessed again.
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Publication Release Date: Apr. 10, 2006
Revision A2