S1D15715 Epson Electronics America, Inc., S1D15715 Datasheet - Page 22

• Manufacturer Part Number: S1D15715
• Description: Liquid Crystal Display =lcd Driver
• Manufacturer: Epson Electronics America, Inc.

S1D15715 Series Technical Manual
6.2 DDRAM
6.2.1 DDRAM
The DDRAM stores pixel data for LCD. It is in a 33 (4 page×8 bit+1) × 102bit array.
Desired bits can be accessed by specifying page and column addresses.
As is shown in Fig.3, the D7 to D0 display data from the MPU corresponds to the LCD common direction.
Moreover, reading from and writing to the display RAM from the MPU side is performed through the I/O buffer,
which is an independent operation from signal reading for the liquid crystal driver
Consequently, even if the display data RAM is accessed asynchronously during liquid crystal display, it will not
cause adverse effects on the display (such as flickering).
6.2.2 Page address circuit
As shown in Fig.4, the page address of the DDRAM is specified using the page address set command. To
access the data using a new page, the page address is respecified.
Page address 4H (D3, D2, D1, D0=0, 1, 1, 0) is DDRAM area dedicate to the indicator, and display data D0 is
only valid.
6.2.3 Column address circuit
Designate the column side address of the indication data RAM as shown in Fig.4, using the column address
setting command.
read/write command is input, the MPU can make access to the indication data in succession.
Also, as shown in Fig.5, after an access has been made to the final column address (65H), the column address
will return to (00H) and the page address will be automatically incremented (by +1).
Thanks to this feature, it is possible to write continuous data being divided between adjoining pages.
Furthermore, after accesses have been made to the final addresses of both of the page and column (column=65H
and page=3H), both of the column address and the page address returns to (00H).
(The page will not increment to 4H. Therefore, be careful when executing “read modify write” processes).
Also, as shown in Table 4, the correlation between the column address of the indication data RAM and the
segment output can be reversed by use of the ADC select command (segment driver direction select command).
Thanks to this feature, IC layout limitations when constituting a LCD module can be lessened.
16
Column Address
Reverse Direction
Normal Direction
D0
D1
D2
D3
D4
-
Since the designated column address increments (+1) each time an indication data
0 1 1 1
1 0 0 0
0 0 0 0
0 1 1 1
1 0 0 0
DDRAM
SEG101
SEG0
00H
0
0
0
0
0
SEG100
SEG1
01H
Table 4
EPSON
Fig.3
SEG99
SEG2
02H
COM0
COM1
COM2
COM3
COM4
-
Display on LCD
SEG99
SEG2
63H
SEG100 SEG101
SEG1
64H
SEG0
65H
Rev.1.0