HD66766R Datasheet, PDF (46/97 Pages) Hitachi Semiconductor – 132 x 176-dot Graphics LCD Controller/Driver for 65K Colors

HD66766R
Rev. 1.0-1 / September 2002
High-Speed Burst RAM Write Function
The HD66766R has a high-speed burst RAM-write function that can be used to write data to RAM in
one-fourth the access time required for an equivalent standard RAM-write operation. This function is
especially suitable for applications that require the high-speed rewriting of the display data, for example,
display of color animations, etc.
When the high-speed RAM-write mode (HWM) is selected, data for writing to RAM is once stored to the
HD66766R internal register. When data is selected four times per word, all data is written to the on-chip
RAM. While this is taking place, the next data can be written to an internal register so that high-speed
and consecutive RAM writing can be executed for animated displays, etc.
Microcomputer
16
Address
counter
(AC)
16
Resistor 1 Resistor 2 Resistor 3 Resistor 4
48
"0000"H "0001"H
"0002"H "0003"H
GRAM
Figure 33 Flow of Operation in High-Speed Consecutive Writing to RAM
CS*
(input)
123412341234
DB15-0
(input / output)
Index
(R22)
RAM RAM R4M RAM RAM RAM RAM RAM RAM RAM RAM RAM
data data data data data data data data data data data data
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12)
RAM write
execution time
RAM write
execution time
RAM write
execution time *
Index
(R22)
RAM write data
(48 bit)
RAM data 1 to 4 RAM data 5 to 8 RAM data 9 to 12
RAM address
(AC15 to 0)
“0000”H
“0004”H
“0008”H
“000A”H
* The lower two bits of the address must be set in the following way in high-speed write mode.
When D0 becomes 0, the lower two bits of the address must be set to “11”.
Wen D1 becomes 1, the lower two bits of the address must be set to “00”.
Note: When a high-speed RAM write is canceled, the next instruction must only be
executed after the RAM write execution time has elapsed.
Figure 34 Example of the Operation of High-Speed Consecutive Writing to RAM
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