HD66773R Datasheet, PDF (81/133 Pages) Renesas Technology Corp – 262,144-color, 132 x 176-dot Graphics Controller Driver for TFT LCD panels

HD66773R
7. Read/Write mode 3: AM = 0, LG2–0 = 100/101
This mode is used when data are horizontally written in high-speed with performing compare operation on
the GRAM data (base data) and the value set in the compare register (CP15-0). The compare operation is
performed on the GRAM read-out data and the value set in the compare register by word. When the result
of the comparison satisfies a condition, the data sent from the microcomputer are written to GRAM. In the
read operation, the GRAM data is not read out to the microcomputer but retained temporarily in the read-
data latch of the HD66773R. Accordingly, the read operation can be performed using the same pulse width
with the write-access pulse (68-system: ENABLE “High” level width, 80-system: ENABLE “Low” level
width), but requires the same bus cycle time as the normal read operation. In this operation, the write-data
mask function (WM15–0) is available. After writing, the address counter (AC) automatically increments
by 1 (I/D = 1) or decrements by 1 (I/D = 0), and jumps to the counter at the opposing edge of the next one-
raster-row below after when the counter reaches either left or right edge of GRAM.
Operation Examples:
1) I/D = "1", AM = "0", LG2-0 = "100" (matched write)
2) CP15-0 = "2860"H
2) WM15-0 = "0000"H
3) AC = "0000"H
WM15
WM0
Write-data mask: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Compare register:
Read data (1):
CP15
CP0
00 1 01 00 0 0 11 00 00 0
Matched
Compare
Operation
DB17
DB10 DB8
DB1
00 1 01 00 0 0 11 00 00 0 ^C
Write data (1):
Read data (2):
10 1 11 10 0
00 0 01 11 1
0 11 00 00 0
Compare
operation
00000 00 0
C
Write data (2):
11 00 00 11 10 000 00 0
Conditional
replacement
R
10 1 11 10 00 11 00 00 0
Conditional
replacement
R
0 00 01 11 10 00 00 00 0
"0000"H
"0001"H
10 1 11 10 00 11 0 00 00 ^{0 00 01 11 10 00 00 00 0}
Matched replacement write data (1)
GRAM
Rev.1.10, Jun.21.2003, page 81 of 133