W925EP01 Datasheet, PDF (67/108 Pages) Winbond – 8-BIT CID MICROCONTROLLER

W925EP01/ W925EP01FG
Examples of Timed Assessing are shown below.
Example 1: Valid access
MOV TA, #0AAh
MOV TA, #055h
MOV CHPCON, #I
;3 M/C
;3 M/C
;3 M/C
Example 2: Invalid access
MOV TA, #0AAh
MOV TA, #055h
NOP
MOV CHPCON, #I
;3 M/C
;3 M/C
;1 M/C
;3 M/C
Example 3: Invalid access
MOV TA, #0AAh
NOP
MOV TA, #055h
MOV CHPCON, #I
;3 M/C
;1 M/C
;3 M/C
;3 M/C
Note: M/C = Machine Cycles
In the first examples, the writing to the protected bits is done before the 3 machine cycle window
closes. In Example 2, 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 3, 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.
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Publication Release Date: Apr. 10, 2006
Revision A2