hd66789 Renesas Electronics Corporation., hd66789 Datasheet - Page 60

• Manufacturer Part Number: hd66789
• Description: 528-channel, One-chip Driver For Amorphous Tft Panels With 262,144-color Display Ram, Power Supply Circuit, And Gate Circuit
• Manufacturer: Renesas Electronics Corporation.

HD66789
Read Data Read from GRAM (R22h)
RD17–0: Read 18-bit data from GRAM. The bit assignment for the data that are read out from GRAM is
different according to the interface.
When data are read out from GRAM to the microcomputer, the first word read immediately after GRAM
address set are latched in the internal read-data latch, and thereby the data in the data bus (DB17–0) are
nullified. The second word is read as valid data. When the HD66789 performs an internal bit processing,
such as logical operation, the data latched in the read-data latch are used to complete it by single read out
operation. The data are expanded internally into 18 bits before going through the logical operation. When
the 8-/16-bit interfaces are selected, GRAM data in the LSBs of R and B pixels are not read out. This
function is not available in the RGB interface mode.
Rev.0.12, May 09 2003, page 60 of 156
R/W
R
RS
1
GRAM data
18-bit interface
Output
Read
data
RD
R5
17
DB
17
RD
R4
16
DB
16
RD
R3 R2
15
DB
15
Read data from GRAM: Bit assignment
RAM Read data (RD17-0) The pin assignment for DB17-0 varies for each interface (see below).
RD
DB
14
14
R1
RD
DB
13
13
RD
R0
12
DB
12
RD
G5
11
DB
11
One pi xel
RD
G4
10
DB
10
RD
G3
DB
9
9
RD
G2
DB
8
8
RD
DB
G1 G0
7
7
RD
DB
6
6
RD
B5
DB
5
5
RD
B4
DB
4
4
RD
B3
DB
3
3
RD
B2
DB
2
2
RD
B1
DB
1
1
RD
Preliminary
B0
DB
0
0