HD66765 Datasheet, PDF (54/71 Pages) Hitachi Semiconductor – 396-channel Segment Driver with Internal RAM for 4096-color Displays

HD66765
5. Read/Write mode 1: AM = 0, LG2–0 = 001/010/011
This mode is used when the data is horizontally written at high speed by performing a logical
operation with the original data. It reads the display data (original data), which has already been
written in the GRAM, performs a logical operation with the write data sent from the microcomputer,
and rewrites the data to the GRAM. This mode reads the data during the same access-pulse width
(68-system: enabled high level, 80-system: RD* low level) as the write operation since reading the
original data does not latch the read data into the microcomputer but temporarily holds it in the read-
data latch. However, the bus cycle requires the same time as the read operation. The write-data mask
function (WM11–0) is also enabled in these operations. After writing, the address counter (AC)
automatically increments by 1 (I/D = 1) or decrements by 1 (I/D = 0), and automatically jumps to the
counter edge one-raster-row below after it has reached the left or right edges of the GRAM.
tion ^{Operation Examples:}
1) I/D = "1", AM = "0", LG2-0 = "001" (Logical OR)
a _{2) WM11—0 = "000"H}
ific ^{3) AC = "0000"H}
DB11
DB0
c _{Write-data mask: 0 0 0 0 0 0 0 0 0 0 0 0}
e _DB11
DB0
p _{Read data (1):}
100110010100
S _{Write data (1):}
101111000110
y _{Read data (2):}
000011110000
ar _{Write data (2):}
110000111000
Logical operation
(OR)
Logical operation
(OR)
101111010110
110011111000
in _"0000"H
"0001"H
lim 1 0 1 1 1 1 0 1 0 1 1 0 1 1 0 0 1 1 1 1 1 0 0 0
Read data (1) + Write data (1) Read data (2) + Write data (2)
"0002"H
Pre ^GRAM
Figure 40 Writing Operation of Read/Write Mode 1
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