Display Data Ram - Epson S1D15722 Series Technical Manual

6. FUNCTIONAL DESCRIPTION

6.2 Display Data RAM

6.2.1 Display Data RAM
This RAM for storing display dot data is comprised of 184 × 224 × 2 bits. The desired bit is accessible by
specifying page address and column address.
When 4 gray scales are selected with the set display mode command, the input display data is processed as a
pair of 2 bits each. Combination is
RAM bit data (higher bit, lower bit) = (D1, D0), (D3, D2), (D5, D4), (D7, D6)
When RAM bit data is gray scales 1 and 2, gray scale display will be provided according to parameters of set
gray scale pattern command.
When binary display is selected with the set display mode command, 1-bit of built-in RAM corresponds to 1
dot of pixel. When RAM bit data is "1", black display appears. When RAM data is "0", white display
appears.
RAM bit data
"1": ON
"0": OFF
Since display data D7 to D0 from MPU corresponds to the common direction of LCD as shown in Fig.6.3
and Fig.6.4, higher degree of freedom is achieved in configuring display with less constraints on display data
transfer if the S1D15722 series is used for the multi-chip.
Read/write from MPU to RAM is performed via I/O buffer, which is controlled independently of liquid
crystal drive RAM. Therefore, even if MPU makes an asynchronous access to RAM during liquid crystal
display, it does not have an adverse effect on the display.
(D1, D0) (0, 0) (1, 1) (1, 1)
(D3, D2) (1, 1) (0, 0) (0, 0)
(D5, D4) (0, 0) (1, 0) (0, 1)
(D7, D6) (0, 0) (0, 0) (0, 0)
---
Display Data RAM
D0 0 1 1 1
D1 1 0 0 0
D2 0 0 0 0
D3 0 1 1 1
D4 1 0 0 0
---
Display Data RAM
16
= (1, 1): Gray scale 3
= (1, 0): Gray scale 2
= (0, 1): Gray scale 1
= (0, 0): Gray scale 0
Black (in normal display mode)
White (in normal display mode)
(0, 0)
(0, 0)
(0, 0)
(0, 0)
Fig.6.3 4-Gray Scale Display
0
0
0
0
0
Fig.6.4 Binary Display
EPSON
Black (in normal display mode)
White (in normal display mode)
COM0
COM1
COM2
COM3
---
Liquid Crystal Display
COM0
COM1
COM2
COM3
COM4
---
Liquid Crystal Display
S1D15722D01B000 Technical Manual (Rev.1.1)