hd66765 Renesas Electronics Corporation., hd66765 Datasheet - Page 54

• Manufacturer Part Number: hd66765
• Description: 396-channel Segment Driver With Internal Ram For 4096-color Displays - Hitachi Semiconductor
• Manufacturer: Renesas Electronics Corporation.

HD66765
5. Read/Write mode 1: AM = 0, LG2–0 = 001/010/011
Operation Examples:
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.
1) I/D = "1", AM = "0", LG2-0 = "001" (Logical OR)
2) WM11—0 = "000"H
3) AC = "0000"H
Write-data mask:
Read data (1):
Write data (1):
Read data (2):
Write data (2):
1 0 1 1 1 1 0 1 0 1 1 0
Read data (1) + Write data (1)
"0000"H
DB11
DB11
0
1
1 0 1 1 1 1 0 0 0 1 1 0
0 0 0 0 1 1 1 1 0 0 0 0
1 1 0 0 0 0 1 1 1 0 0 0
0 0 0 0 0 0 0 0 0 0 0
0 0 1 1 0 0 1 0 1 0 0
Figure 40 Writing Operation of Read/Write Mode 1
1 1 0 0 1 1 1 1 1 0 0 0
Read data (2) + Write data (2)
GRAM
"0001"H
DB0
DB0
54
Logical operation
(OR)
Logical operation
(OR)
1 0 1 1 1 1 0 1 0 1 1 0
1 1 0 0 1 1 1 1 1 0 0 0
"0002"H