HD66765 Datasheet, PDF (49/71 Pages) Hitachi Semiconductor – 396-channel Segment Driver with Internal RAM for 4096-color Displays

HD66765
Logical/Compare Operation Function
The HD66765 performs a logical operation or conditional replacement between the two-byte write data
sent from the microcomputer and the read data from the GRAM. The logical operation function has four
types: replacement, OR, AND, and EOR. The conditional replacement performs a compare operation for
the set value of the compare register (CP11–0) and the read data value from the GRAM, and rewrites
only the pixel data in the GRAM that satisfies the conditions (in a byte unit). This function can be used
when a particular color is selectively rewritten. The swap function or write-data mask function can be
effectively used.
Table 24 Logical/Compare Operation
n _{Bit Setting}
tio ^{LG2 LG1 LG0 Description of Logical/Compare Operation Function}
a ⁰
0
0
Writes the data written from the microcomputer directly to the GRAM. Only
ific ^{write processing is performed since the data in the read-data latch is not used.}
0
0
1
ORs the data in the read-data latch and the data written by the microcomputer.
Writes the result to GRAM. Read, modify, or write processing is performed.
c ₀
1
0
ANDs the data in the read-data latch and the data written by the
e _{microcomputer. Writes the result to GRAM.}
p ₀
1
1
EORs the data in the read-data latch and the data written by the
S _{microcomputer. Writes the result to GRAM.}
y ₁
0
0
Compares the data in the read-data latch and the set value of the compare
r _{register (CP11–0). When the read data matches CP11–0, the data from the}
a _{microcomputer is written to the GRAM. Only the particular color specified in}
in ^{the compare register can be rewritten. Read, modify, or write processing is}
performed.
lim ¹
0
1
Compares the data in the read-data latch and the set value of the compare
register (CP11–0). When the read data does not match CP11–0, the data from
e^{the microcomputer is written to the GRAM. Colors other than the particular}
r one specified in the compare register can be rewritten. Read, modify, or write
P ^{processing is performed.}
1
1
0
Compares the data written to the GRAM by the microcomputer and the set
value of the compare register (CP11–0). When the write data matches
CP11–0, the data from the microcomputer is written to the GRAM. Only write
processing is performed.
1
1
1
Compares the data written to the GRAM by the microcomputer and the set
value of the compare register (CP11–0). When the write data does not match
CP11–0, the data from the microcomputer is written to the GRAM. Only write
processing is performed.
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