HD66760 Datasheet, PDF (59/105 Pages) Hitachi Semiconductor – 104 X 80-dot Graphics LCD Controller/Driver for 256 Colors

HD66760
6. Read/Write mode 2: AM = 1, LG1–0 = 001/010/011
This mode is used when the data is vertically 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 can read the data during the same access-pulse width (68-system: enabled high level,
80-system: RD* low level) as for the write operation since the read operation of the original data does not
latch the read data into the microcomputer and 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 256, and automatically jumps to the upper-right edge (I/D = 1) or upper-left
edge (I/D = 0) following the I/D bit after it has reached the lower edge of the GRAM.
Operation Examples:
1) I/D = "1", AM = "1", LG2-0 = "001" (OR), SWP = "1"
2) WM15–0 = "FF00"H
3) AC = "000"H
WM15
WM0
Write-data mask: 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0
DB15
DB0
Read data (1): _{1 0 0 0 1 0 0 1 0 1 0 1 0 0 0 0}
Write data (1): _{1 0 1 1 1 1 0 0 0 1 1 0 0 0 0 1}
Read data (2):
Write data (2):
00 00 11 1 100 00 0 110
11 00 00 1 110 00 1 100
Read data (3):
Write data (3):
00 0 01 110 1 11 00 11 0
01 1 10 100 00 0 11 11 1
Swap
0 110 00 0 110 1 111 0 0
Logical operation (OR)
1 1 1 0 1 0 01 1 1 1 1 1 1 0 0
Swap
10 00 1 100 11 00 00 1 1
Logical operation (OR)
1 0 0 01 1 1 1 1 1 0 0 0 1 1 1
Swap
00 0 11 11 101 1 10 100
Logical operation (OR)
0 0 0 11 1 1 1 1 1 1 1 0 1 1 0
"0000"H
"0001"H
"0000"H * * * * * * * * ^{1 1 1 1 1 1 0 0 Read data (1) + write data (1)}
"0080"H * * * * * * * * ^{1 1 0 0 0 1 1 1 Read data (2) + write data (2)}
"0100"H * * * * * * * * ^{1 1 1 1 0 1 1 0 Read data (3) + write data (3)}
"4F00"H
Notes: 1. The bits in the GRAM indicated by '*' are not changed.
2. After writing to address 4F00H, the AC jumps to 0001H.
GRAM
Figure 39 Writing Operation of Read/Write Mode 2