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23.5
Display Memory
The S1C17624/622 includes a 56-byte display memory (address 0x53c0 to address 0x53f7). The S1C17604/602/621
includes a 40-byte display memory (address 0x53c0 to address 0x53e7). The correspondence between memory bits
and COM/SEG pins varies depending on the conditions selected, as follows.
(1) Drive duty (1/8, 1/4, 1/3, 1/2 duty or static drive)
(2) SEG pin assignment (normal or inverted)
(3) COM pin assignment (normal or inverted)
Figures 23.5.1 to 23.5.10 show the correspondence between display memory and COM/SEG pins for each drive
duty.
Writing 1 to a display memory bit corresponding to pixels on the LCD panel turns that pixel on, while writing 0
turns the pixel off. Since the display memory is a RAM allowing reading and writing, bits can be controlled indi-
vidually using logic operation instructions (read-modify-write instructions).
Bits not assigned to the display area within the display memory can be used as general-purpose RAM that can be
read and written to.
Display area selection (when 1/4, 1/3, 1/2 duty or static drive is selected)
When 1/4, 1/3, 1/2 duty or static drive is selected, two screen areas can be reserved within the display memory,
and DSPAR/LCD_DCTL register can be used to switch between the screens. Setting DSPAR to 0 selects dis-
play area 0; setting to 1 selects display area 1.
SeG pin assignment
The display memory address assignment for the SEG pins can be inverted using SEGREV/LCD_DCTL regis-
ter. When SEGREV is set to 1 (default), memory addresses are assigned to SEG pins in ascending order. When
SEGREV is set to 0, memory addresses are assigned to SEG pins in descending order. (See Figures 23.5.1 to
23.5.10.)
COM pin assignment
The display memory bit assignment for the COM pins can be inverted using COMREV/LCD_DCTL register.
When COMREV is set to 1 (default), memory bits are assigned to COM pins in ascending order. When COM-
REV is set to 0, memory bits are assigned to COM pins in descending order. (See Figures 23.5.1 to 23.5.10.)
Bit
D0
D1
D2
D3
D4
D5
D6
D7
SEGREV = 1
SEGREV = 0
S1C17624/604/622/602/621 TeChniCal Manual
Address
...
Display area
...
...
Figure 23.
5.1 S1C17624/622 Display Memory Map (1/8 duty)
Seiko epson Corporation
23 lCD DRiVeR (lCD)
COMREV = 1 COMREV = 0
...
...
COM0
COM1
Unused
COM2
area
COM3
Unavailable
(general-
area
COM4
purpose
COM5
memory)
COM6
COM7
COM7
COM6
COM5
COM4
COM3
COM2
COM1
COM0
23-9
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