hd66765 Renesas Electronics Corporation., hd66765 Datasheet - Page 56

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

HD66765
7. Read/Write mode 3: AM = 0, LG2–0 = 100/101
Operation Examples:
This mode is used when the data is horizontally written by comparing the original data and the set
value of compare register (CP11–0). It reads the display data (original data), which has already been
written in the GRAM, compares the original data and the set value of the compare register in byte
units, and writes the data sent from the microcomputer to the GRAM only when the result of the
comparison satisfies the condition. This mode reads the data during the same access-pulse width (68-
system: enabled high level, 80-system: RD* low level) as 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 = "100" (matched write)
2) CP11—0 = "530"H
3) WM11—0 = "000"H
4) AC = "0000"H
Write-data mask:
Compare register:
Read data (1):
Write data (1):
Read data (2):
Write data (2):
1 0 1 1 1 1 0 0 0 1 1 0
Matched replacement
write data (1)
"0000"H
DB11
DB11
0
0
0 1 0 1 0 0 1 1 0 0 0 0
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
1 0 1 0 0 1 1 0 0 0 0
Figure 42 Writing Operation of Read/Write Mode 3
(Matched)
0 0 0 0 1 1 1 1 0 0 0 0
GRAM
"0001"H
DB0
DB0
56
Compare
operaton
Compare
operaton
C
C
R
R
Conditional
replacement
Conditional
replacement
1 0 1 1 1 1 0 0 0 1 1 0
0 0 0 0 1 1 1 1 0 0 0 0