W77E468 查看數據表（PDF） - Winbond

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W77E468

8 BIT MICROCONTROLLER

Winbond 

Preliminary W77E468

Examples of Timed Assessing are shown below.

Example 1: Valid access

MOV TA, #0AAh 3 M/C

MOV TA, #055h 3 M/C

MOV WDCON, #00h 3 M/C

Note: M/C = Machine Cycles

Example 2: Valid access

MOV TA, #0AAh

MOV TA, #055h

NOP

SETB EWT

3 M/C

3 M/C

1 M/C

2 M/C

Example 3: Invalid access

MOV TA, #0AAh

MOV TA, #055h

NOP

NOP

CLR POR

3 M/C

3 M/C

1 M/C

1 M/C

2 M/C

Example 4: Invalid Access

MOV TA, #0AAh 3 M/C

NOP

1 M/C

MOV TA, #055h 3 M/C

SETB EWT

2 M/C

In the first two examples, the writing to the protected bits is done before the 3 machine cycle window

closes. In Example 3, however, the writing to the protected bit occurs after the window has closed,

and so there is effectively no change in the status of the protected bit. In Example 4, the second write

to TA occurs 4 machine cycles after the first write, therefore the timed access window in not opened

at all, and the write to the protected bit fails.

ON-CHIP MTP ROM CHARACTERISTICS

The W77E468 has several modes to program the on-chip MTP ROM. All these operations are

configured by the pins RST, ALE, PSEN , A9CTRL(P3.0), A13CTRL(P3.1), A14CTRL(P3.2),

OECTRL(P3.3), CE (P3.6), OE (P3.7), A0(P1.0) and VPP( EA ). Moreover, the A15−A0(P2.7−P2.0,

P1.7−P1.0) and the D7−D0(P0.7−P0.0) serve as the address and data bus respectively for these

operations.

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