MS51
Nov. 28, 2019 Page 229 of 491 Rev 1.00
MS51 32K SERIES TECHNICAL REFERENCE MANUAL
Example 3,
MOV TA,#0AAH ;3 clock cycles
MOV TA,#55H ;3 clock cycles
MOV WDCON,#data1 ;3 clock cycles
ORL BODCON0,#data2 ;4 clock cycles
Example 4,
MOV TA,#0AAH ;3 clock cycles
NOP ;1 clock cycle
MOV TA,#55H ;3 clock cycles
ANL BODCON0,#data ;4 clock cycles
In the first example, the writing to the protected bits is done before the 3-clock-cycle window closes. In
example 2, however, the writing to BODCON0 does not complete during the window opening, there
will be no change of the value of BODCON0. In example 3, the WDCON is successful written but the
BODCON0 write is out of the 3-clock-cycle window. Therefore, the BODCON0 value will not change
either. In Example 4, the second write 55H to TA completes after 3 clock cycles of the first write TA of
AAH, and thus the timed access window is not opened at all, and the write to the protected byte
affects nothing.
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