HD66760 Datasheet, PDF (58/105 Pages) Hitachi Semiconductor – 104 X 80-dot Graphics LCD Controller/Driver for 256 Colors

HD66760
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 swap function (SWP) or write-data mask function
(WM15–0) are 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.
Operation Examples:
1) I/D = "1", AM = "0", LG2-0 = "001" (OR), SWP = "0"
2) WM15–0 = "0000"H
3) AC = "000"H
WM15
WM0
Write-data mask: _{0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0}
DB15
DB0
Read data (1): _{1 0 0 1 1 0 0 1 0 1 0 0 0 0 1 1}
Write data (1): _{1 0 1 1 1 1 0 0 0 1 1 0 0 0 0 1}
Logical operation
(OR)
10 1 111 0 10 110 00 1 1
Read data (2):
Write data (2):
00 00 11 1 100 00 0 000
11 00 00 1 110 00 1 100
Logical operation
(OR)
11 00 11 1 110 00 1 10 0
Read data (3):
Write data (3):
00 0 01 110 10 0 00 11 0
01 1 10 100 00 0 11 11 1
Logical operation
(OR)
01 1 11 110 10 0 11 11 1
"0000"H
"0001"H
"0002"H
1 0 1 1 1 1 0 1 0 1 1 0 0 0 1 1 1 1 0 0 1 1 1 1 1 0 0 0 1 1 0 0 0 1 1 11 11 0 1 0 0 1 1 1 1 1
Read data (1) + write data (1) Read data (2) + write data (2)
Read data (3) + write data (3)
GRAM
Figure 38 Writing Operation of Read/Write Mode 1