hd66765 Renesas Electronics Corporation., hd66765 Datasheet - Page 31

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

Read Data from GRAM (R22h)
RD11–0: Read 12-bit data from the GRAM. When the data is read to the microcomputer, the first-word
read immediately after the GRAM address setting is latched from the GRAM to the internal read-data
latch. The data on the data bus (DB11–0) becomes invalid and the second-word read is normal.
When bit processing, such as a logical operation, is performed within the HD66765, only one read can be
processed since the latched data in the first word is used.
Second word
Second word
R/W
First word
First word
R
RS
1
i) Data read to the microcomputer
DB15
Sets the I/D, AM, HSA/HEA, and
VSA/VEA bits
0
Read-data latch -> DB11-0
GRAM -> Read-data latch
Read-data latch -> DB11-0
GRAM -> Read-data latch
Dummy read (invalid data)
Dummy read (invalid data)
Read (data of address N)
Read (data of address M)
DB14
0
Address: M set
Address: N set
DB13
0
Figure 23 Read Data from GRAM Instruction
DB12
0
Figure 24 GRAM Read Sequence
DB11
RD
11
DB10
RD
10
DB9
RD
9
31
Second word
Second word
DB8
RD
First word
First word
8
ii) Logical operation processing in the HD66765
DB7
RD
7
DB6
RD
6
Sets the I/D, AM, HSA/HEA, and
VSA/VEA bits
Automatic address update: N +
GRAM -> Read-data latch
GRAM -> Read-data latch
Dummy read (invalid data)
Dummy read (invalid data)
Write (data of address N+ )
Read (data of address N)
DB5
RD
5
DB11-0 -> GRAM
DB11-0 -> GRAM
Address: N set
DB4
RD
4
DB3
RD
3
DB2
RD
2
HD66765
DB1
RD
1
DB0
RD
0