hd66789 Renesas Electronics Corporation., hd66789 Datasheet - Page 100

• 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
High-Speed Burst RAM Write Function
The HD66789 incorporates high-speed burst RAM-write function, which writes data to RAM in one-fourth
the access time required for a standard RAM-write operation. This function is especially useful for
applications which require the high-speed rewrite of the display data such as display of colored moving
picture and so on.
In the high-speed RAM write mode (HWM), data to write to RAM is temporarily stored to the internal
register of HD66789. The data storage in the register is executed by word. When the data storage
operation is executed 4 times, all data stored in the register are written to RAM at once. While the data is
being written from the register to RAM, another set of data is being written to the register. This function
enables high-speed and consecutive RAM write, which are required in displaying moving pictures and so
on.
Rev.0.12, May 09 2003, page 100 of 156
(input/output)
(input/output)
DB15-0
DB15-0
(input)
(input)
(input)
(input)
CS*
CS*
E
E
Address
Index
Index
(R22)
(R22)
counter
(AC)
RAM address
(AC15 to 0)
16
RAM
data
RAM
RAM write data
Operational flow of High-Speed Burst RAM Write
data
(72 bits)
1
1
1
1
Note : When terminating the high-speed RAM write, wait for the time required for the RAM write execution
The lower two bits of the address must be set as follows in the high-speed write mode.
When ID0 = 0, set the lower two bits of the address to 11.
When ID1 = 1, set the lower two bits of the address to 00.
RAM
data
2
2
2
“0000H”
(bus cycle line (tCYC) in the normal write mode) before executing the next instruction.
High-Speed Consecutive Write to RAM
RAM
data
3
3
3
Register 1
RAM
data
4
4
4
RAM write
RAM write
execution time
execution time
“0001H”
RAM data 1 to 4
RAM data 1 to 4
“0000”H
“0000”H
RAM
data
1
1
5
RAM
data
2
2
6
Register 2
“0002H”
RAM
data
3
3
7
Microcomputer
RAM
data
4
4
8
GRAM
RAM write
RAM write
execution time
execution time
RAM data 5 to 8
RAM data 5 to 8
“0003H”
RAM
data
1
1
9
Register 3
“0004”H
“0004”H
18
72
RAM
data
2
2
10
RAM
data
3
3
11
RAM
data
12
4
4
RAM write
RAM write
execution time
execution time
Register 4
RAM data 9 to 12
RAM data 9 to 12
“0008”H
“0008”H
Index
Index
(R22)
(R22)
“000A”H
“000A”H
Preliminary